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Mar 1978

Volume 15, Issue 2, pp. 157-820


Electron–solid interactions: Their nature and consequences

C. B. Duke

J. Vac. Sci. Technol. 15, 157 (1978); http://dx.doi.org/10.1116/1.569447 (13 pages) | Cited 3 times

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During the past two decades electron scattering and emission spectroscopies have become utilized almost universally to characterize the properties of solid surfaces. Two major trends have created this situation: The increasing availability of suitable, convenient experimental apparatus, and the recognition and exploitation of those features of electron–solid interactions which render these measurements sensitive to surface properties. Whereas prior Welch Award lectures have dealt with the former trend, the latter is examined herein. Three concepts are central to an understanding of the interaction of ’’low‐energy’’, 10≲E≲103‐eV electrons with the constituents of solids. First, their strong Coulombic interaction with the valence electrons of the solid renders their mean free paths for inelastic collisions of atomic dimensions, i.e., 2≲λ≲20 Å. Thus, elastically scattered or emitted electrons in this energy range must have emanated from the uppermost few atomic layers of the solid. Second, the interactions of these electrons with the core electrons are comparable to those with the valence electrons. Therefore, multiple elastic scattering as well as rapid energy loss characterizes their scattering and emission. Third, resonant processes associated with electronic states localized at a surface can be as important as inelastic processes in establishing surface sensitivity. Examples of this phenomenon are found in resonant field emission through adsorbates and resonant photoemission associated with the excitation of transitions characteristic of adsorbed complexes. The major portion of this article is devoted to an indication of how exploitations of these three concepts have led to quantitative surface analysis methodologies for metals and covalent solids. In the case of polymers and molecular solids, however, one further concept is required: the localization of electronic states caused by fluctuations in relaxation energy. These fluctuations lead to localized molecular ion (or exciton) states rather than extended band states. The final portion of this article is devoted to exploring the consequences of this additional concept and how it led to the invention of yet another electron spectroscopy, contact charge exchange spectroscopy, for the examination of molecular ion states in polymers.
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61.05.J- Electron diffraction and scattering

Magnetron sputtering: basic physics and application to cylindrical magnetrons

John A. Thornton

J. Vac. Sci. Technol. 15, 171 (1978); http://dx.doi.org/10.1116/1.569448 (7 pages) | Cited 60 times

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Magnetron sputtering sources can be defined as diode devices in which magnetic fields are used in concert with the cathode surface to form electron traps which are so configured that the E×B electron‐drift currents close on themselves. Coaxial cylindrical magnetron sputtering sources in which post or hollow cathodes are operated in axial magnetic fields have been reported for a number of years. However, their performance is limited by end losses. A remarkable performance is achieved when the end losses are eliminated by proper shaping of the magnetic field or by using suitably placed electron‐reflecting surfaces. High currents and sputtering rates can be obtained, nearly independent of voltage, even at low pressures. This characterizes what has been defined as the magnetron mode of operation. This paper reviews the basic principles that underly the operation of dc sputtering sources in the magnetron mode with particular emphasis on cylindrical magnetrons. The important attributes of these devices as sputtering sources are also reviewed.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
52.75.-d Plasma devices

Abstract: High‐rate sputter deposition—circular magnetrons

David B. Fraser

J. Vac. Sci. Technol. 15, 178 (1978); http://dx.doi.org/10.1116/1.569449 (1 page)

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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
81.15.Cd Deposition by sputtering
85.40.Bh Computer-aided design of microcircuits; layout and modeling

Abstract: MOS metallization via automatic ’’S‐Gun’’ planetary deposition system

T. N. Fogarty, D. B. Fraser, and W. J. Valentine

J. Vac. Sci. Technol. 15, 178 (1978); http://dx.doi.org/10.1116/1.569450 (1 page)

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81.15.Cd Deposition by sputtering
85.30.-z Semiconductor devices
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Planar magnetron sputtering

Robert K. Waits

J. Vac. Sci. Technol. 15, 179 (1978); http://dx.doi.org/10.1116/1.569451 (9 pages) | Cited 44 times

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The technology is reviewed with emphasis on implementation. PM sputtering is characterized by cathode potentials of 300–700 V and sputtering gas pressures of 1‐15 mTorr (0.1–2 Pa). Deposition rates are proportional to power density, which in turn is primarily limited by the thermal conductivity and cooling efficiency of the target. rf operating characteristics are similar to dc, but plasma plus target impedance is somewhat higher. For both rf and dc PM sputtering higher power (or current) densities are achievable at lower target potentials than for conventional sputtering. Permanent magnets and electro‐magnets have been used to produce closed electron‐trapping field patterns adjacent to the surface of both circular and rectangular planar targets. Plasma intensity and target erosion is a maximum where the magnetic field lines are parallel to the cathode surface. Deposition uniformity can be achieved by substrate motion combined with optimized magnet geometry. For a given material at equivalent deposition rates PM sputtering results in less substrate heating due to reduced bombardment by dark‐space‐accelerated electrons.
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81.15.Cd Deposition by sputtering
68.55.-a Thin film structure and morphology
52.75.-d Plasma devices

Diagnostic methods for sputtering plasmas

John A. Thornton

J. Vac. Sci. Technol. 15, 188 (1978); http://dx.doi.org/10.1116/1.569452 (5 pages) | Cited 25 times

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This paper reviews the parameters that can be used to characterize glow discharge plasmas of the type used in many sputtering devices, and the methods available to measure those parameters. The review is also generally applicable to the plasmas used in ion plating and plasma‐activated reactive evaporation. The objective is to provide a brief overview and a guide to the literature for thin‐film specialists. The emphasis is on negative glow‐type plasmas, and the diagnostic techniques of optical spectroscopy and electrostatic probes, since these methods are particularly effective for such plasmas and are relatively easy to implement in the laboratory. Guidelines are presented for a corona interpretation of absolute intensity line emission measurements in terms of the density of energetic electrons in an Ar‐negative glow. Cases are described in which electrostatic probe measurements were used to investigate performance characteristics of cylindrical‐post and cylindrical‐hollow magnetron sputtering sources.
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52.70.-m Plasma diagnostic techniques and instrumentation
52.75.-d Plasma devices
79.20.-m Impact phenomena (including electron spectra and sputtering)

Plasma diagnostics with electric probes

R. M. Clements

J. Vac. Sci. Technol. 15, 193 (1978); http://dx.doi.org/10.1116/1.569453 (6 pages) | Cited 36 times

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The use of Langmuir or electric probes in collisionless plasmas which are of interest in sputter coating is briefly reviewed. The analysis of the probe current–voltage characteristic, especially that from double floating probes, to yield the plasma parameters, the electron temperature, and the ionization density, is considered in some detail. This paper is intended to be of use to the experimentalist who wishes to use Langmuir probes as a diagnostic tool but does not really want to become an expert in all aspects of probe theory and operation.
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52.70.Ds Electric and magnetic measurements

Measurement of plasma discharge characteristics for sputtering applications

E. Eser, R. E. Ogilvie, and K. A. Taylor

J. Vac. Sci. Technol. 15, 199 (1978); http://dx.doi.org/10.1116/1.569454 (4 pages) | Cited 10 times

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Plasma and characteristics of rf and dc discharges for sputtering were measured by a cylindrical‐type electrostatic probe. Space potentional, floating potential, electron temperature, and plasma density were monitored as a function of discharge voltage, substrate bias, and probe position within the chamber. A description of the probe and supporting circuit used to plot the current–voltage characteristic is given. The electrostatic probe was shown to be a useful tool for characterizing sputtering process and with suitable system calibration, can be used to enhance repeatability of the sputtering process.
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52.80.Hc Glow; corona
52.80.Pi High-frequency and RF discharges
52.70.Ds Electric and magnetic measurements
81.15.Cd Deposition by sputtering

Abstract: Optical spectroscopy for glow discharge sputtering diagnostics and process control

J. E. Greene

J. Vac. Sci. Technol. 15, 203 (1978); http://dx.doi.org/10.1116/1.569478 (2 pages)

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Abstract Unavailable
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52.80.Hc Glow; corona
79.60.Bm Clean metal, semiconductor, and insulator surfaces
82.80.Dx Analytical methods involving electronic spectroscopy
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
81.15.Cd Deposition by sputtering

Mass spectrometric study of plasma etching

Bruce A. Raby

J. Vac. Sci. Technol. 15, 205 (1978); http://dx.doi.org/10.1116/1.569479 (4 pages) | Cited 12 times

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A quadrupole mass spectrometer gives much useful information about plasma etching processes on silicon and its compounds. The present work confirms some of the known or postulated chemistry in the plasma and raises further questions about the understanding of the process. The instrument enables dynamic optimization of process parameters and provides a variety of diagnostic information. In particular, it allows the detection of etching endpoints and thereby provides a sensitive technique for controlling the etching process. The technique appears to substantially reduce or eliminate the need for calibration. The account discusses endpoints for polycrytalline silicon, silicon dioxide, silicon nitride, and some cases involving photoresist.
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81.65.-b Surface treatments
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
52.75.-d Plasma devices

Abstract: Partial pressure analysis of chromium source material

F. J. Tams and B. Halon

J. Vac. Sci. Technol. 15, 209 (1978); http://dx.doi.org/10.1116/1.569480 (1 page)

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Abstract Unavailable
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.40.Rs Electrical and magnetic properties related to treatment conditions
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Rate and pressure dependence of contaminants in vacuum‐deposited aluminum films

R. W. Springer and D. S. Catlett

J. Vac. Sci. Technol. 15, 210 (1978); http://dx.doi.org/10.1116/1.569481 (5 pages) | Cited 6 times

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Experiments have been conducted to measure the quantity of trapped impurities in electron‐beam‐deposited aluminum films. The depositions were conducted at the 1.3×10−4–1.3×10−2 Pa pressure range with rates varying from a few tenths to 7.0 nm/s. An RGA was used to record the residual gas spectrum before and during all runs. The films were analyzed by sputter profiling and Auger electron spectroscopy. The chief contaminants found were carbon and oxygen. The carbon contaminant tracked the gauge pressure over two orders of magnitude ranging from a few atomic percent to the 500–1000 ppm range. The partial pressures of H2O, O2, and other gases were varied during deposition to determine their individual roles in contaminating the films. As a result, a relationship between the residual gas spectrum, and chemical analysis was found.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

UHV facility for metal–semiconductor thin‐film studies

C. A. Crider, J. M. Poate, and J. E. Rowe

J. Vac. Sci. Technol. 15, 215 (1978); http://dx.doi.org/10.1116/1.569482 (4 pages) | Cited 3 times

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A unique multifunction apparatus consisting of a surface analysis chamber operating at 1×10−8 Pa connected by a 4.5‐m‐long beam line to a 3.75‐MeV Van de Graaff accelerator operating at 1×10−4 Pa is described. The bakeable, all‐metal sealed beam line contains collimating, blocking, focusing, and steering facilities for the MeV ion beam and is differentially pumped with a turbomolecular pump to 4×10−7 Pa after a mild (100°C) bakeout. The chamber contains surface preparation equipment, a double‐pass CMA for AES and ELS, and facilities for metal evaporation at P?8×10−7 Pa from an electron‐beam source while simultaneously performing MEED. A specially designed manipulator allows samples to be cleaned, annealed, and characterized prior to in situ evaporation. The resulting metal–semiconductor couple may also be annealed in situ and characterized by AES, MEED, and Rutherford Backscattering Spectroscopy.
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07.30.Hd Vacuum testing methods; leak detectors
73.61.Cw Elemental semiconductors
73.61.Ey III-V semiconductors
73.61.Ga II-VI semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
73.40.Ns Metal-nonmetal contacts

Effects of accumulated film layers on the accuracy of quartz film thickness monitors

J. S. Heyman and W. E. Miller

J. Vac. Sci. Technol. 15, 219 (1978); http://dx.doi.org/10.1116/1.569483 (4 pages)

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The effect of accumulation layers on the accuracy of quartz thin‐film thickness monitors is evaluated. Use of an expanded plane wave ultrasonic propagation theory correctly accounts for observed experimental data. The magnitude of the maximum errors calculated for simply reversing the order of a series of aluminum gold deposits is on the order of 5%. If one totally neglects intervening layers, multiple film propagation and nonlinearity can produce errors greater than 50%.
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68.60.-p Physical properties of thin films, nonelectronic
68.35.Gy Mechanical properties; surface strains
68.35.Iv Acoustical properties
43.35.Ns Acoustical properties of thin films

Electron spectroscopic study of oxygen‐plasma‐treated polymer surfaces

James M. Burkstrand

J. Vac. Sci. Technol. 15, 223 (1978); http://dx.doi.org/10.1116/1.569484 (4 pages) | Cited 7 times

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Oxygen plasma treatment of ABS polymer surfaces has the effect of increasing the adhesion of evaporated metal films on those surfaces. To help understand this, surfaces of commercial ABS and polypropylene were examined with ESCA both before and after oxygen plasma treatment. The plasma treatment was found to change the basic chemical nature of the polymer surface by increasing the number of single and double bonds between carbon and oxygen atoms. It is suspected that these additional carbon–oxygen chemical bonds affect the adhesion between polymers and metals. In addition to the carbon–oxygen bond formation, the plasma treatment removed residual impurities of silicon and increased the residual amounts of other metallic impurities originating in the bulk. The binding energies of these metallic impurities are all indicative of oxides.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.65.-b Surface treatments
46.55.+d Tribology and mechanical contacts
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

High resolution Auger sputter profiling study of the effect of phosphorus pileup on the Si–SiO2 interface morphology

S. A. Schwarz, C. R. Helms, W. E. Spicer, and N. J. Taylor

J. Vac. Sci. Technol. 15, 227 (1978); http://dx.doi.org/10.1116/1.569485 (4 pages) | Cited 7 times

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We have used Auger electron spectroscopy in conjunction with sputter etching and crater‐edge profiling to study the distribution of phosphorus near the Si–SiO2 interface and the effect of the phosphorus distribution on the width of the interface transition region. The samples studied consisted of thermal oxides approximately 1000‐Å‐thick grown on Si (111) substrates with initial phosphorus concentrations up to 6×1020 cm−3. Phosphorus pileup at the Si–SiO2 interface was observed with the phosphorus peak (after correcting for electron escape depth effects) on the Si side within 5 Å of the interface. The 10%–90% width of the Si–SiO2 transition region as measured by the SiLVV transition varies from 25 (low doping limit) to 38 Å (bulk doping level of 6×1020 cm−3). Results are interpreted in terms of a recently proposed model for the Si–SiO2 interface.
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68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Correlation between the defect structure and electrical properties of deformed Si surfaces

K. Murty, H. Suga, B. Lalevic, and S. Weissmann

J. Vac. Sci. Technol. 15, 231 (1978); http://dx.doi.org/10.1116/1.569486 (4 pages) | Cited 2 times

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Deformation by bending of Si wafers with [112], [111], and [100] surface orientation was produced by sputtering tantalum films on clean Si and on Si surface with a thermally grown oxide. Deposition of 0.5–1‐μm Ta films produced radii of curvature in the Si wafers of from 350 to 50 m, respectively, as measured by the ABAC method. Stress on the Si surface as a function of annealing temperature exhibited a maximum of 400°C of 500 g/mm2 and 650 g/mm2 with and without oxide layer. Stress on tantalum films at 400°C was found to be 276.3 kg/mm2. At 300°C, stress on Ta film increased with Ta film thickness from 70 to 150 kg/mm2. Transverse and sectional x‐ray topographs have revealed small dislocation loops at the deformed Si surface. Defect structure produced by bending was correlated with the electrical measurements on the Si MOS configuration with thin and thick oxide, using conductance and capacitance methods. The effects of induced defects were studied by measuring the density and energy distribution of the surface states, surface potential, and flat band voltage. I–V characteristics of the oxide film indicated Ta diffusion through SiO2 to the Si surface.
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62.20.F- Deformation and plasticity
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
73.20.-r Electron states at surfaces and interfaces
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Improvement of the diffusion barrier properties of rf‐sputtered molybdenum

R. S. Nowicki and I. Wang

J. Vac. Sci. Technol. 15, 235 (1978); http://dx.doi.org/10.1116/1.569487 (3 pages) | Cited 1 time

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In a contact metallization employing Mo as a thin‐film ’’diffusion barrier’’, we have observed that this refractory metal does not exhibit optimum barrier properties when rf sputtered in argon. It was found that the use of ∠1500 Å of rf‐sputtered Mo between Si and Au results in extensive Si and Au intermixing in <30 min at 450°C. Auger depth profile analysis confirmed that both Si and Au had moved through the Mo. This would preclude subsequent processing involving elevated temperature, as in a Silox deposition. The intermixing appears to proceed via a grain boundary diffusion mechanism (Ea=0.21 eV). Significant improvement in the intermixing time was obtained by the controlled incorporation of N2 into the Mo via reactive rf sputtering. A possible model for this improvement will be presented using the data obtained from microstructural analysis of the nitrided and unnitrided films.
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66.30.-h Diffusion in solids
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Abstract: Chemical structure of the Al–SiO2 interface

Y. E. Strausser and K. S. Majumder

J. Vac. Sci. Technol. 15, 238 (1978); http://dx.doi.org/10.1116/1.569488 (2 pages) | Cited 8 times

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Abstract Unavailable
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68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Solid‐state reaction of Ti and sapphire

M. B. Chamberlain

J. Vac. Sci. Technol. 15, 240 (1978); http://dx.doi.org/10.1116/1.569489 (3 pages) | Cited 4 times

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The growth‐rate of the products of the solid‐state reaction between a polycrystalline Ti thin films and polished. (111) ‐oriented sapphire (A1203) wafers was determined from 757 to 839 K by combing Auger electron spectroscopy and Ar‐ion‐beam sputtering. A parabolic growth rate was fit to the data: The activation energy of the rate constant was 170 kJ mol−1 K−1. The rate constant was smaller for a Ti thin film epitaxially grown on a wafer.
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82.20.Pm Rate constants, reaction cross sections, and activation energies
81.10.Jt Growth from solid phases (including multiphase diffusion and recrystallization)
82.80.-d Chemical analysis and related physical methods of analysis

Abstract: Auger analysis of Ta/Ta oxide diffusion barrier to reduce Al–polycrystalline Si reaction

J. K. Howard and P. L. Garbarino

J. Vac. Sci. Technol. 15, 243 (1978); http://dx.doi.org/10.1116/1.569490 (1 page)

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Abstract Unavailable
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66.30.Ny Chemical interdiffusion; diffusion barriers
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.20.Pm Rate constants, reaction cross sections, and activation energies
81.05.Bx Metals, semimetals, and alloys

Low‐temperature interdiffusion in titanium–permalloy thin‐film diffusion couples

R. J. Miller and A. Gangulee

J. Vac. Sci. Technol. 15, 244 (1978); http://dx.doi.org/10.1116/1.569491 (4 pages)

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Interdiffusion in thin‐film Ti–Permalloy (nominally 81 at. % Ni+19 at. % Fe) diffusion couples has been investigated in the temperature range 200°–350°C. These diffusion couples were isothermally annealed in vacuum for times up to 6×105 s, and their magnetic properties such as the coercivity, the anisotropy field, the saturation magnetization, and electrical properties such as the sheet resistance and the sheet magnetoresistance were monitored as functions of time. From the observed changes in these properties and from concurrent x‐ray diffraction measurements, it may be concluded that the dominant mechanism in this interdiffusion process is the volume diffusion of Ti in Permalloy; the activation energy for this process is estimated to be 1.9 eV.
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66.30.Ny Chemical interdiffusion; diffusion barriers

Abstract: Auger analysis of thin‐film sandwich structures

M. M. Nanda

J. Vac. Sci. Technol. 15, 248 (1978); http://dx.doi.org/10.1116/1.569492 (1 page)

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Abstract Unavailable
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68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
68.55.-a Thin film structure and morphology
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination

Auger electron spectroscopy studies of I–III–VI2 chalcopyrite compounds

L. L. Kazmerski, D. L. Sprague, and R. B. Cooper

J. Vac. Sci. Technol. 15, 249 (1978); http://dx.doi.org/10.1116/1.569561 (5 pages) | Cited 3 times

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Auger electron spectroscopy (AES) spectra are presented for Cu ternary chalcopyrite compounds. CuInS2, CuInSe2, and CuInTe2 thin films, bulk polycrystalline, and single‐crystal samples are examined and their AES spectra are compared. The validity of quantitative analysis methods [(1) calibration with Ag‐standard, (2) utilization of sensitivity factors, and (3) calibration with specific ternary standards] is examined and the results are compared. Consistent results are obtained for polycrystalline (bulk and thin film) samples, but not for the single‐crystal cases. It is found that peak width variations must be considered in the single‐crystal data which vary due to diffraction channeling effects. Calculations, taking these variations into account, yield the expected results.
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82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
68.55.-a Thin film structure and morphology
84.60.Jt Photoelectric conversion
81.10.Fq Growth from melts; zone melting and refining

Abstract: New semiconductor heterostructures

L. Esaki and L. L. Chang

J. Vac. Sci. Technol. 15, 254 (1978); http://dx.doi.org/10.1116/1.569562 (1 page) | Cited 1 time

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Abstract Unavailable
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68.55.-a Thin film structure and morphology
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
75.20.Ck Nonmetals

Surface segregation of Sn during MBE of n‐type GaAs established by SIMS and AES

K. Ploog and A. Fischer

J. Vac. Sci. Technol. 15, 255 (1978); http://dx.doi.org/10.1116/1.569563 (5 pages) | Cited 26 times

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Auger electron spectroscopy (AES) and secondary ion mass spectroscopy (SIMS) have been used to study in situ the surface segregation of Sn, which occurred during molecular‐beam epitaxy (MBE) of Sn‐doped GaAs films. With both surface diagnostic techniques, a significant amount of Sn, about three orders of magnitude larger than the portion being incorporated into the growing film was detected in the outermost atomic layers (∠10–20 Å thick) of the prepared film. The surface segregation of Sn started at a substrate temperature as low as 490° C and increased with temperature and−to some extent−with increasing dopant concentration. Thus, the measured doping profiles of Sn‐doped GaAs layers, when grown above 490° C, deviated considerably from the ideal profile calculated from the molecular beam intensity of the dopant. The surface segregation of Sn during epitaxial growth was also found in Sn‐doped GaAs films prepared by liquid‐phase epitaxy (LPE) from Ga solutions.
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64.75.-g Phase equilibria
68.55.-a Thin film structure and morphology
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Abstract: Optical properties of sputtered films

E. Krikorian

J. Vac. Sci. Technol. 15, 260 (1978); http://dx.doi.org/10.1116/1.569564 (1 page)

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Abstract Unavailable
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75.20.Ck Nonmetals
42.79.-e Optical elements, devices, and systems
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Electrochromism in WO3 films with BaO additions

B. J. Molnar, A. R. Haranahalli, and D. B. Dove

J. Vac. Sci. Technol. 15, 261 (1978); http://dx.doi.org/10.1116/1.569565 (3 pages)

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Films of WO3 with various amounts of BaO additions were deposited from multiple evaporation sources onto glass substrates heated to 100°C. The atomic percent of Ba in each film with respect to W was determined using particle‐induced x‐ray emission analysis (PIXIE). Compositional variations with film depth were examined using Auger electron spectroscopy combined with ion beam milling. The electrochromic coloration and decoloration behavior was measured in an electrochemical cell. It was found that additions of Ba as small as 10 at. % measurably reduced the amount of coloration induced per given amount of charge injected into the film. The amount of inhibition of electrochromic coloration was found to increase with increasing Ba concentration. At Ba concentrations greater than 45% the coloration effect was virtually eliminated. Ba additions greater than 45 at. % were also found to induce crystallization in the films.
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82.45.-h Electrochemistry and electrophoresis
78.20.Jq Electro-optical effects
61.72.jn Color centers

Abstract: Growth of polycrystalline PbS films

H. Elabd and A. J. Steckl

J. Vac. Sci. Technol. 15, 264 (1978); http://dx.doi.org/10.1116/1.569566 (1 page) | Cited 2 times

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Abstract Unavailable
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81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
75.20.Ck Nonmetals
73.61.Cw Elemental semiconductors
73.61.Ey III-V semiconductors
73.61.Ga II-VI semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors

Absorption coefficient measurements for vacuum‐deposited Cu‐ternary thin films

L. Y. Sun, L. L. Kazmerski, A. H. Clark, P. J. Ireland, and D. W. Morton

J. Vac. Sci. Technol. 15, 265 (1978); http://dx.doi.org/10.1116/1.569567 (4 pages) | Cited 36 times

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The absorption coefficients, α, of polycrystalline CuInS2 and CuInSe2 thin films have been determined at room temperature using transmission measurements. For each of these semiconductors, an absorption edge corresponding to the direct band‐gapl transition (1.54±0.02 eV for CuInS2 and 1.00±0.02 eV for CuInSe2) is observed in the α vs hν spectrum. In p‐type CuInS2 thin films, another edge is evident at lower energies (1.41×1.42 eV) and is attributed to transitions from a copper vacancy band to the conduction band. The effects of annealing on the absorption coefficient spectra of these chalcopyrite materials are presented. An additional absorption region, appears in the CuInSe2 spectra at higher energies (hν∠1.28 eV), and is critically dependent on the Se concentration of the films. This effect is discussed in terms of band structure, film stoichiometry and structural characteristics of the films.
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75.20.Ck Nonmetals
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds

Optical properties of selectively absorbing metal insulator composite films

H. G. Craighead and R. A. Buhrman

J. Vac. Sci. Technol. 15, 269 (1978); http://dx.doi.org/10.1116/1.569568 (3 pages) | Cited 16 times

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The optical properties of Ni/Al2O3, V/Al2O3, V/SiO2, V/MgO, Fe/Al2O3 and Fe/MgO composite films have been studied with consideration given to their applicability as selective solar energy absorbers. Thin films were produced by coevaporation and the microstructure examined by electron microscopy. The optical properties of Ni/Al2O3 composites, measured over the range of the solar spectrum, are in good accord with the predictions of Maxwell–Garnett theory provided the Ni volume fraction is ≲0.2. The Ni/Al2O3 films have excellent spectral selectivity for the absorption of solar radiation with a solar absorptivity of 0.94 obtained for a film produced with a graded composition. Low‐temperature emissivities of ∠0.1 have been obtained for Ni/Al2O3 on a highly reflecting metal backing. The composite Ni/Al2O3 is stable at high temperatures in air. The V and Fe composite studies have optical properties different in character from the predictions of Maxwell–Garnett theory and are not as suitable for solar energy applications as Ni composites.
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84.60.Ve Energy storage systems, including capacitor banks
78.66.-w Optical properties of specific thin films
78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
81.40.Tv Optical and dielectric properties related to treatment conditions

Technology of ion beam sources used in sputtering

Harold R. Kaufman

J. Vac. Sci. Technol. 15, 272 (1978); http://dx.doi.org/10.1116/1.569569 (5 pages) | Cited 36 times

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The technology of broad‐beam ion sources is reviewed from the viewpoint of the sputtering–deposition user. This review includes a short description of the development of discharge chambers, accelerator systems, and cathodes; the present alternatives for these components and the expected future improvements.
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52.80.Dy Low-field and Townsend discharges
07.77.-n Atomic, molecular, and charged-particle sources and detectors
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Thirty‐centimeter‐diameter ion milling source

Raymond S. Robinson

J. Vac. Sci. Technol. 15, 277 (1978); http://dx.doi.org/10.1116/1.569570 (4 pages) | Cited 6 times

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A 30 cm beam diameter ion source has been designed and fabricated for micromachining and sputtering applications. An argon ion current density of 1 mA/cm2 at 500 eV ion energy was selected as a design operating condition. The completed ion source met the design criteria at this operating condition with a uniform and well‐collimated beam having an average variation in current density of ±5% over the center of 20 cm of the beam. This ion source has a multipole magnetic field that employs permanent magnets between permeable pole pieces. Langmuir probe surveys of the source plasma support the design concepts of a multipole field and a circumferential cathode to enhance plasma uniformity.
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41.75.Ak Positive-ion beams
41.75.Cn Negative-ion beams
06.60.Vz Workshop procedures (welding, machining, lubrication, bearings, etc.)
29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative

Significance of negative ion formation in sputtering and SIMS analysis

J. J. Cuomo, R. J. Gambino, J. M. E. Harper, J. D. Kuptsis, and J. C. Webber

J. Vac. Sci. Technol. 15, 281 (1978); http://dx.doi.org/10.1116/1.569571 (7 pages) | Cited 27 times

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An unexpected substrate etching phenomenon during the sputtering of certain intermetallic compounds has been found to be caused by a large flux of negative metal ions from the sputtering target. The substrates directly under the target in a diode geometry are etched (eroded) rather than coated with a film. The occurrence of this substrate etching has been correlated with negative ion yields measured by secondary ion mass spectroscopy (SIMS). We find a high yield of negative metal ions from several intermetallic compounds in addition to the highly ionic compounds previously reported. A model based on electron charge transfer is presented which predicts when negative ion formation will be important, and the dependence of etch rate on target voltage is also treated. We predict that negative ion effects will be found in the sputtering of a wide range of compounds.
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82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
79.20.-m Impact phenomena (including electron spectra and sputtering)
81.05.Bx Metals, semimetals, and alloys
07.75.+h Mass spectrometers

Abstract: Model of bias sputtering applied to the control of Nb film properties

Eric Kay and Gunther Heim

J. Vac. Sci. Technol. 15, 288 (1978); http://dx.doi.org/10.1116/1.569572 (2 pages)

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73.61.At Metal and metallic alloys
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Reduction of contamination in triode sputtering systems

W. D. Ryden, J. B. Bindell, L. H. Holschwandner, and E. F. Labuda

J. Vac. Sci. Technol. 15, 290 (1978); http://dx.doi.org/10.1116/1.569573 (6 pages)

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The fabrication of silicon integrated circuits with a beam lead metallization system consisting of Ti, Pt, and Au requires an effective technique for depositing thin films (500–2000 Å) of Ti and Pt. Altough sputtering is a particularly advantageous technique, it does have one particular disadvantage: Films deposited by sputtering are prone to contamination, since the ions causing the sputtering cannot be completely restricted to the desired target material. The contamination problem can be more serious in a supported plasma apparatus (triode), as opposed to the usual diode configuration, because of the additional fixturing which can act as sources of contamination. The contamination in a triode system has been examined and the major source was found to be the plasma confinement tube. A model has been developed that explains the origin of the contamination; the contamination results obtained by Auger analysis are in full agreement with the model. Furthermore, based on the model, the confinement tube was split into electrically isolated segments. With this split tube configuration the contamination from the tube was reduced by over an order of magnitude.
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81.15.Cd Deposition by sputtering
85.40.Bh Computer-aided design of microcircuits; layout and modeling
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
52.75.-d Plasma devices

Selective resputtering‐induced anisotropy in amorphous films

R. J. Gambino and J. J. Cuomo

J. Vac. Sci. Technol. 15, 296 (1978); http://dx.doi.org/10.1116/1.569574 (6 pages) | Cited 11 times

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A model will be presented to explain the bias voltage dependence of magnetic anisotropy in sputtered amorphous films of gadolinium cobalt alloys. It has been found that the magnetic anisotropy increases with bias voltage up to a critical bias voltage (∠150 V depending on the sputter gas) then decreases precipitously at higher voltages. The model used to explain this behavior is based on selective resputtering of atoms in different surface sites causing an anisotropic distribution of Gd and Co atoms with respect to the growth direction. For example, a Gd adatom in contact with three surface atom neighbors can have 0, 1, 2, or 3 cobalt neighbors. The sputtering threshold for each type of Gd adatom will be different so those with a low threshold will be selectively removed giving a structural anisotropy. This anisotropic atomic distributions can cause different kinds of anisotropy with respect to the growth direction depending on the type of amorphous film. For example, both easy‐axis (GdCo) and hard‐axis (GdFe) magnetic anisotropies have been observed. It may be possible to extend this model to other types of anisotropy in amorphous films.
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75.50.Kj Amorphous and quasicrystalline magnetic materials
75.30.Gw Magnetic anisotropy
81.15.Cd Deposition by sputtering

Hydrogen evolution from plasma‐deposited amorphous silicon films

K. J. Matysik, C. J. Mogab, and B. G. Bagley

J. Vac. Sci. Technol. 15, 302 (1978); http://dx.doi.org/10.1116/1.569575 (3 pages) | Cited 7 times

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The temperature dependence of hydrogen evolution from amorphous silicon films prepared by plasma deposition using a silane–argon mixture was studied by line‐of‐sight mass spectrometry. The structure changes accompanying hydrogen evolution were simultaneously studied with reflection high‐energy electron diffraction (RHEED). Mass spectrometric analysis during linear temperature sweeps showed that H2 was the evolving species indicating that hydrogen atom recombination occurs prior to desorption. H or SiHx were not detected. The evolution spectrum consisted of two broad peaks. The temperature corresponding to the initiation of evolution, the maximum evolution rate and the termination of evolution were dependent on deposition parameters. Attempts at depopulating specific hydrogen binding states by isothermal heat treatments indicated the existence of a broad range of states. The amorphous to crystalline transition was initiated subsequent to hydrogen depletion and at 760° C+10° independent of deposition parameters.
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61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Abstract: Scale‐up problems in e‐beam evaporation and sputtering

J. L. Hughes

J. Vac. Sci. Technol. 15, 305 (1978); http://dx.doi.org/10.1116/1.569576 (1 page)

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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Large‐scale sputtering of indium–tin oxide

F. Howard Gillery

J. Vac. Sci. Technol. 15, 306 (1978); http://dx.doi.org/10.1116/1.569577 (3 pages) | Cited 3 times

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The development of a reactive dc diode sputtering system for the deposition of indium oxide coatings by scanning large substrates will be described. Coatings of 5 Ω/sq, with 86% light transmission, having a specific resistivity of less than 2.5×10−4Ω cm are routinely produced on curved and flat substrates up to 5 ft2. Effects particularly noticeable in large sputtering systems, such as secondary electron emission, plasma focusing, imperfections due to cathode nonuniformity, arcing caused by cathode contamination, and substrate temperature gradients, will be emphasized.
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81.15.Cd Deposition by sputtering
81.05.Kf Glasses (including metallic glasses)
81.65.-b Surface treatments

Multisource deposition rate control using a mass spectrometer as a sensing element

H. Lutz

J. Vac. Sci. Technol. 15, 309 (1978); http://dx.doi.org/10.1116/1.569578 (4 pages) | Cited 2 times

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A deposition rate controller for a multisource, high‐rate, electron‐beam evaporation system for simultaneous deposition of two to four materials is described. The system utilizes a quadrupole mass spectrometer as a material selective sensor to monitor the fluxes of the different evaporants, and a dedicated minicomputer serves as a process controller to adjust the deposition sources to maintain the desired rates. The computer can control a variable leak valve instead of one of the evaporation sources to maintain the desired partial pressure of a background gas. Experience gained in using the system is discussed.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
74.25.-q Properties of superconductors
68.55.-a Thin film structure and morphology
07.75.+h Mass spectrometers

Ion nitriding of steels

P. C. Jindal

J. Vac. Sci. Technol. 15, 313 (1978); http://dx.doi.org/10.1116/1.569579 (5 pages) | Cited 11 times

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This paper deals with the ’’ion‐nitriding’’ method of nitriding various grades of steels in a laboratory model furnace. Four different grades of steels such as AISI 4140, Nitralloy 135 Mod., high‐speed steel M2 and stainless steel 304 were ion nitrided at different temperatures with cycle times ranging from 1 to 36 h in a gaseous mixture of nitrogen and hydrogen under a total pressure of 7 Torr (9.1×103 Pa). Results obtained with 4140 steel show that ion nitriding at 950°F is much faster than conventional gaseous nitriding. At a given temperature of ion nitriding, case depth versus treatment time follows a parabolic law for all four grades of steels. Current theoretical and experimental evidence has been used to explain different nitriding rates observed for various steels. Finally results of ion nitriding performed at 750°F have been presented to show the versatility of this process.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.40.Gh Other heat and thermomechanical treatments

Abstract: RFI/EMI frrom rf‐induced gas discharges used for sputter deposition and sputter etching

Lawrence T. Lamont

J. Vac. Sci. Technol. 15, 318 (1978); http://dx.doi.org/10.1116/1.569580 (1 page)

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52.80.-s Electric discharges

Profile control by reactive sputter etching

H. W. Lehmann and R. Widmer

J. Vac. Sci. Technol. 15, 319 (1978); http://dx.doi.org/10.1116/1.569581 (8 pages) | Cited 38 times

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Reactive sputter etching in fluorocarbon gases (i.e. CF4, CHF3) not only results in a large increase of the etch rates, but it can also be used for a high fidelity pattern transfer from patterns delineated in positive photoresist into underlaying substrates (i.e. Si, SiO2, Si3N4). Square wave gratings with micron and submicron periodicities and etch depths of up to 3 μm have been etched. A relatively large etch selectivity of SiO2 over Si has been observed (etch rate ratio=15:1). Reactive sputter etching is primarily a chemical process due to highly reactive species produced on the substrate surface by an ion–molecule reaction between ions from the plasma and neutral gas molecules impinging onto the substrate surface.
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81.65.-b Surface treatments
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Abstract: Mechanisms in plasma etching

J. W. Coburn and H. F. Winters

J. Vac. Sci. Technol. 15, 327 (1978); http://dx.doi.org/10.1116/1.569582 (2 pages) | Cited 4 times

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52.80.Hc Glow; corona
81.65.-b Surface treatments
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Flow rate effects in plasma etching

B. N. Chapman and V. J. Minkiewicz

J. Vac. Sci. Technol. 15, 329 (1978); http://dx.doi.org/10.1116/1.569583 (4 pages) | Cited 17 times

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Experimental data concerning the dependence of plasma etching rates on the flow rate of the etching gas have been analyzed in terms of the consumption of the gas, and a simple model is proposed to explain the observed dependence. The decrease in etch rates at low flow rates is shown to be due to an inadequate supply of the etching gas; at high flow rates, etching is retarded because active species are pumped away.
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52.40.Hf Plasma-material interactions; boundary layer effects
81.65.-b Surface treatments
85.40.Bh Computer-aided design of microcircuits; layout and modeling

Abstract: Mechanisms of silicon etching by CF4 plasma

J. L. Mauer, J. S. Logan, L. B. Zielinski, and G. C. Schwartz

J. Vac. Sci. Technol. 15, 333 (1978); http://dx.doi.org/10.1116/1.569538 (1 page)

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81.65.-b Surface treatments
81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties

Abstract: Plasma etching of Si and SiO2−The effect of oxygen additions to CF4 plasmas

C. J. Mogab, A. C. Adams, and D. L. Flamm

J. Vac. Sci. Technol. 15, 333 (1978); http://dx.doi.org/10.1116/1.569539 (1 page)

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81.65.-b Surface treatments

Reactive ion etching of aluminum and aluminum alloys in an rf plasma containing halogen species

P. M. Schaible, W. C. Metzger, and J. P. Anderson

J. Vac. Sci. Technol. 15, 334 (1978); http://dx.doi.org/10.1116/1.569540 (4 pages) | Cited 25 times

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An etching method capable of producing vertical‐walled high‐resolution patterns in aluminum and aluminum alloy films is described. The process consists of rf sputter etching in a plasma containing ion species, which react with the metal to form volatile or easily sputtered compounds. The presence of reactive species greatly enhances the etch rate, while the electric field maintains the directionality inherent in the sputtering process. Halogen ion species, as obtained in rf plasmas containing a partial pressure of Cl2, Br2, HCl, HBr, or CCl4, were used to produce reactive ion etching of Al. The etch rate in a CCl4 plasma at a power input of 0.6 W/cm2 is as high as 5000 Å/min. Variations in reaction rate with rf power, reactant concentration, reactant flow rate, temperature, gas pressure, batch size, and residual gas contamination are discussed. Etch rate data for various materials found suitable for masking are also presented.
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81.05.Bx Metals, semimetals, and alloys
52.75.-d Plasma devices
85.40.Bh Computer-aided design of microcircuits; layout and modeling

Analysis of the imaging accuracy in reactive ion etching

Katsumi Ukai and Kunio Hanazawa

J. Vac. Sci. Technol. 15, 338 (1978); http://dx.doi.org/10.1116/1.569541 (3 pages) | Cited 3 times

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In reactive ion etching the factors which have influence on imaging accuracy consist of the swell of the resist mask, the reduction of the mask, and the undercutting. We investigated these factors about polycrystalline Si, Al, and Mo films on Si wafer. The undercutting depends on the overetching time and the ion current. In the case of etching poly‐Si film, it corresponds with the change of the impedence of CF4 discharge. Also it was made clear by comparing the experimental results with the calculated field model that the size of undercutting depends on not only the random motion of the ions but the lack of uniformity of the cathode fall caused from the ruggedness of the pattern on the substrate surface. This fact is consistent with the phenomenon that the dimensional change by etching within the substrate depends on the pattern size.
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81.65.-b Surface treatments
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Abstract: Surface studies of Y2O3 doped CeO2 and ZrO2 thin films

T. L. Barr, L. B. Welsh, F. R. Szofran, J. E. Greene, and R. E. Klinger

J. Vac. Sci. Technol. 15, 341 (1978); http://dx.doi.org/10.1116/1.569542 (2 pages) | Cited 2 times

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68.60.-p Physical properties of thin films, nonelectronic

Combination analysis of metal oxides using ESCA, AES, and SIMS

G. R. Conner

J. Vac. Sci. Technol. 15, 343 (1978); http://dx.doi.org/10.1116/1.569543 (5 pages) | Cited 3 times

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Combination ESCA, AES, and SIMS analyses have been conducted on high purity metal foils of Fe, Ni, Cr, and Mo to investigate oxides formed on sputter‐cleaned surfaces. Results are given for the controlled oxidation of Fe and Ni metals and the rapid sequential analysis by the three techniques. Oxygen signals from the three methods are shown to have identical dependence on oxygen dosage during the initial stages of oxidation for these two metal‐oxygen systems. ESCA and SIMS results of both systems are in agreement with divalent oxide formation at oxygen dosages up to 60 L for Fe and 50 L for Ni. Preliminary results for Cr‐O and Mo‐O systems are also reported.
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82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
81.05.Bx Metals, semimetals, and alloys

AES and XPS of silicon nitride films of varying refractive indices

T. N. Wittberg, J. R. Hoenigman, W. E. Moddeman, C. R. Cothern, and M. R. Gulett

J. Vac. Sci. Technol. 15, 348 (1978); http://dx.doi.org/10.1116/1.569544 (5 pages) | Cited 20 times

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AES and XPS measurements of silicon nitride films with refractive indices ranging from 1.93 to 2.08 have been made. The films studied were grown on silicon (100) substrates by CVD using varying mixtures of silane and ammonia. Earlier AES studies of similar silicon nitride films have suggested that these films are microscopic mixtures of Si and Si3N4. We present XPS data which show that there is no measurable ’’free’’ silicon (i.e. the level of ’’free’’ silicon is ≲3 at. %) in the silicon nitride films with refractive indices ≲2.02. AES data show an increase in oxygen content corresponding to a decrease in refractive index of the silicon nitride films. These AES measurements agree qualitatively with measurements of the physical properties of silicon oxynitride films.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
75.20.Ck Nonmetals

Thickness dependence of structural and electrical properties of Cds films for solar cells

A. Amith

J. Vac. Sci. Technol. 15, 353 (1978); http://dx.doi.org/10.1116/1.569545 (6 pages) | Cited 5 times

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Polycrystalline films of CdS were evaporated on zinc‐plated foils of copper so that different thicknesses were obtained in the same evaporation. The different thicknesses were compared with respect to their surface morphologies, acid etching, grain sizes, grain structure, and orientation as well as crystallographic orientation. Concomitant measurements of the electrical properties as functions of thickness were taken. These included average resistance through the thickness, current–voltage characteristics of diodes prepared by evaporating gold dots on the surfaces, and measurements of capacitance as functions of reverse bias on the same diodes. It was established that grain size, the preferential grain orientation and conelike growth towards the source, the preferential c‐axis orientation towards the source and the surface roughness, all increased as the film thickness increased. Furthermore, it was found that the concentration of free carriers increased with film thickness, the quality of the diode behavior improved considerably in the same manner, and the existence of voltage‐dependent shunting paths diminished as the film thickness increased. An explanation is proposed which relates the observed electrical behavior as a function of thickness to the structural parameters.
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84.60.Jt Photoelectric conversion
81.65.-b Surface treatments
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
81.10.Aj Theory and models of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation

Structure and morphology of chemical‐sprayed CdS films

R. S. Berg, R. D. Nasby, and C. Lampkin

J. Vac. Sci. Technol. 15, 359 (1978); http://dx.doi.org/10.1116/1.569546 (4 pages)

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Chemical spray pyrolysis is a technique for film growth which is of interest because of its potential for very large‐scale, inexpensive production of semiconductor materials such as CdS for photoconductor and photovoltaic applications. In this study, CdS films were prepared by spraying ∠0.1‐M aqueous solutions of CdCl3 and NH2CSNH2 (thiourea) onto SnO2‐coated glass substrates heated to 380°C. The films developed very intricate surface morphologies consisting of a variety of nodular and serpentine structures about 5–10 μm in size. Grain sizes were about 200 nm, with their c‐axis generally normal to the local surface. The grain structure and morphology produce very large optical scattering and high effective absorption for wavelengths larger than the CdS band‐gap wavelength of 500 nm. Films 3–4 μm thick typically have effective absorption constants of about 500 cm−1 at 1000‐nm wavelength. The films were relatively impure, with total impurity contents of about 2 wt. % consisting of reaction products (principally chlorine), impurities picked up from the spray process (oxygen, iron, and others), and mobile glass species (such as sodium and potassium). These impurities may be an important factor in limiting grain size. Electrically, the carrier concentrations are on the order of 1016 cm−3, with mobilities of the order of 10 cm3/V s. Some of the effects of these properties on fabricated CdS/Cu2S photovoltaic devices are discussed.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.-a Thin film structure and morphology
84.60.Jt Photoelectric conversion
72.40.+w Photoconduction and photovoltaic effects

Thickness dependence of an amorphous overlayer Ge film on the electrical conductivity of ultrathin Pt films

S. Ogawa

J. Vac. Sci. Technol. 15, 363 (1978); http://dx.doi.org/10.1116/1.569547 (3 pages)

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The resistance of ultrathin Pt films as influenced by amorphous Ge thin overlayers has been studied. The ratio of change in resistance of the Pt films with overlays of the amorphous Ge is negligibly small for continuous Pt films but is much larger for semicontinuous and discontinuous Pt films, especially for discontinuous ones: As order, these ratio are 10−2, 1, and 102, respectively. The changes in resistance of semicontinuous and discontinuous Pt films markedly depend on the thickness of the overlay. With the thickness of the overlay, at first, the resistance increases slightly for semicontinuous Pt films and decreases rapidly for the discontinuous one, and then decreases for both films to a saturation value (∠60 Å). The decreases in resistance of both Pt films with the thickness of the overlay can be explained by electrical conduction of the localized states in the energy gap of the overlay.
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73.61.At Metal and metallic alloys
73.40.Ns Metal-nonmetal contacts

Reflectance and structure of evaporated chromium and molybdenum films

J. E. Nestell and R. W. Christy

J. Vac. Sci. Technol. 15, 366 (1978); http://dx.doi.org/10.1116/1.569548 (4 pages) | Cited 4 times

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Chromium and molybdenum films deposited in a high vacuum at room temperature are shown to have anomalously low optical reflectance throughout the 0.2–2.5‐μm wavelength range. Deposition at about 700°C for chromium and 1000°C for molybdenum, or postdeposition annealing, gives films with bulk reflectance. X‐ray diffraction and transmission electron microscopy show the films deposited at room temperature to be very fine grained (80–100‐Å grain size). Electrical resistivity of the fine grained films is high (3–5 times bulk). High‐temperature deposition or annealing gives larger grains (≳400 Å) and lower resistivity. A simple model accounts for the resistivity behavior.
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78.66.Bz Metals and metallic alloys
81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties
68.55.-a Thin film structure and morphology
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Thin‐film NiCr resistor

D. M. Buczek

J. Vac. Sci. Technol. 15, 370 (1978); http://dx.doi.org/10.1116/1.569549 (3 pages) | Cited 6 times

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Reactively evaporated NiCr resistors have been produced with slightly negative temperature coefficients of resistance. Evidence from the transmission electron microscope and Auger electron microprobe show these to be cermet structures with multiple conduction mechanisms. A theoretical model initially proposed by Neugebauer for discontinuous films is applied to these thin‐film structures and expanded for the multiple conduction mechanisms and effect of expansion mismatch between the substrate and film.
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84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)
81.05.Mh Cermets, ceramic and refractory composites
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
72.60.+g Mixed conductivity and conductivity transitions

Mass spectrometric solutions to manufacturing problems in the semiconductor industry

Kuo‐chin Lin and James D. Burden

J. Vac. Sci. Technol. 15, 373 (1978); http://dx.doi.org/10.1116/1.569550 (4 pages) | Cited 1 time

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A mass spectrometric method for routine analysis of electronic specialty gases has been established. Methodology for accurate determination of hermetically sealed‐in contaminants of electron devices is described. Leak checking, process monitoring, and process development in sputtering, plasma etching, and CVD are cited.
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82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
07.75.+h Mass spectrometers
85.30.-z Semiconductor devices
85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology

Structural analysis of rf and dc sputtered Nb3Ge thin films containing oxygen

E. I. Alessandrini, R. B. Laibowitz, and C. C. Tsuei

J. Vac. Sci. Technol. 15, 377 (1978); http://dx.doi.org/10.1116/1.569551 (5 pages)

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Using electron microscopy, diffraction, microprobe, scanning microscopy, and nuclear back‐scattering techniques to analyze rf and dc sputtered N3Ge thin films, it was found that the film structure was strongly dependent on film preparation methods. Amorphous Nb3Ge films were prepared by both sputtering techniques, on substrates held at liquid nitrogen temperature. Identical crystallization heat treatments were then carried out in a He furnace at 750°C for 65 h. Analyses by nuclear back‐scattering indicated that crystallized rf‐prepared films contained about three times as much oxygen as crystallized dc films. Structure studies showed that although both types of crystallized films exhibited the A‐15 structure, the data on the rf films indicate the presence of the crystalline oxide, Nb2O5. In addition, the lattice parameter for the rf film was slightly smaller ∗ dc‐prepared films while the grain size of the former is about 10 times larger. These data appear to be correlated to differences in the superconducting transition temperature of both types of films. A high Tc (∠16 K) was observed for rf‐prepared samples. The annealed dc‐sputtered films did not become superconducting for temperatures above 1.5 K. In summary, the results of this work indicate that large grain size is conducive to high Tc superconductivity in Nb–Ge system and provide some evidence for oxygen stabilization of the high TcA‐15 phase.
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74.25.Sv Critical currents
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
68.55.-a Thin film structure and morphology
74.25.-q Properties of superconductors
74.78.-w Superconducting films and low-dimensional structures

Synthesis and physical properties of superconducting compound films formed by the electron‐beam codeposition of the elements

R. H. Hammond

J. Vac. Sci. Technol. 15, 382 (1978); http://dx.doi.org/10.1116/1.569552 (4 pages) | Cited 11 times

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Electron‐beam codeposition of the elements to form certain high critical temperature superconducting materials, in particular A‐15 compounds, has proven to be very useful in research directed at understanding and improving their superconducting properties. This work has used the close control of three or more evaporant sources to reproducibly make specimens that permit studies across selected regions of composition and phase space. The effect of composition and phase, together with the temperature and rate of deposition, on the growth morphology and superconducting properties has been studied. The superconducting properties measured include the critical temperature, ac loss, critical current density, and tunnel junction characteristics. The particular compounds studied include Nb3Sn, Nb3Ge, and V3Si.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
74.78.-w Superconducting films and low-dimensional structures

Niobium nitride thin‐film SQUID’s biased at 20 MHz and 9.2 GHz

S. A. Wolf, F. J. Rachford, and M. Nisenoff

J. Vac. Sci. Technol. 15, 386 (1978); http://dx.doi.org/10.1116/1.569553 (3 pages) | Cited 6 times

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Niobium nitride thin films have been reactively sputtered onto cylindrical quartz substrates. Films 500 Å or thicker, exhibited superconducting transition temperatures in the range 15–16 K, thinner films had lower Tc’s. Good 20‐MHz SQUID behavior was noted in samples incorporating variable thickness weak links in which the ’’local’’ critical temperatures are depressed to about 12 K. Some of these SQUID’s exhibited nearly intrinsic magnetic flux noise. Correlations were obtained between the ratio of quasiparticle diffusion distance to the zero‐temperature coherence length and the quality of the SQUID behavior.
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85.25.-j Superconducting devices
81.15.Cd Deposition by sputtering

Photolithographic fabrication of thin‐film metal–oxide–metal diodes with submicrometer‐square junction areas

R. H. Havemann

J. Vac. Sci. Technol. 15, 389 (1978); http://dx.doi.org/10.1116/1.569554 (3 pages) | Cited 6 times

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A technique is described which uses conventional photolithography in fabricating metal–oxide–metal diodes with submicrometer‐square junction areas. The junction is formed at the edge of the first thin‐film electrode, thereby reducing one dimension of the junction by an order of magnitude or more over linewidths obtainable by standard photolithographic methods. Although the technique is applied specifically to the fabrication of a metal–oxide–metal diode array, it is generally applicable to other thin‐film devices requiring submicrometer‐square junction areas.
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85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
73.40.Rw Metal-insulator-metal structures

Photolithographic fabrication of lead alloy Josephson junctions

R. H. Havemann, C. A. Hamilton, and Richard E. Harris

J. Vac. Sci. Technol. 15, 392 (1978); http://dx.doi.org/10.1116/1.569555 (4 pages) | Cited 13 times

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Techniques for the photolithographic fabrication of thin‐film Josephson junctions are presented in detail, including metal liftoff processes, lead alloy composition, and formation of tunneling junction barriers using plasma oxidation in an rf discharge. A comparison with earlier rf plasma oxidation studies on Pb(In) –oxide–Pb junctions shows the tunneling resistance of Pb(In,Au) –oxide–Pb(Au) junctions to be nearly two decades lower for a given oxygen pressure in the rf discharge; this difference was attributed to the use of different alloys and sputtering parameter measurement techniques in the respective studies. Typically, tunneling resistance decreased by only 2% after ten thermal cycles, but decreased at an accelerated rate with subsequent cycling. Room‐temperature storage often induced downward resistance changes on the order of 30% per month. Junctions stored at −15°C generally showed little change after a period of three months.
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85.25.-j Superconducting devices

Structural and compositional characterization of sputter‐deposited WC+Co films

E. Eser, R. E. Ogilvie, and K. A. Taylor

J. Vac. Sci. Technol. 15, 396 (1978); http://dx.doi.org/10.1116/1.569556 (5 pages) | Cited 1 time

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WC+Co films were sputter deposited by both rf and dc techniques on the electrically floating flat beryllium substrates. Film thickness varied from 1.0 to 1.68 μm. Structural and compositional analysis of the coatings were done by x‐ray diffraction, SEM, EMA, and AES. Columnar growth and preferential nucleations present in the coatings by dc sputtering were not found in the coating by rf sputtering. X‐ray diffraction showed that dc sputter‐deposited coatings are beta tungsten carbide. Compositional analysis showed that the films were deficient in both carbon and cobalt and this deficiency was more pronounced in the films deposited by rf sputtering. Oxygen concentrations were found to be lower and argon concentrations higher for films deposited by rf sputtering. Results show the effect of ion bombardment on the substrates during deposition by the negative self‐bias obtained by electrically floating the substrates. Carbon deficiency is associated with the low sticking coefficient of carbon due to its low mass.
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68.55.-a Thin film structure and morphology
82.80.-d Chemical analysis and related physical methods of analysis
81.15.Cd Deposition by sputtering

Friction and wear results from WC+Co coatings by −dc‐biased rf sputtering in a helium atmosphere

E. Eser, R. E. Ogilvie, and K. A. Taylor

J. Vac. Sci. Technol. 15, 401 (1978); http://dx.doi.org/10.1116/1.569557 (5 pages)

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WC+Co films were deposited on flat polished beryllium substrates by rf sputtering with selected values of −dc bias applied to the substrates. Topographical, structural, and compositional analysis of the coatings were done by SEM, x‐ray diffraction, and EMA. X‐ray diffraction results show the deposits to vary from amorphous to αW2C. Compositional analysis showed variations in carbon and cobalt in relation to the bias level. Friction and wear tests carried out in a helium atmosphere by rotating one specimen in contact with another at constant speed and load for a specified time showed coefficient of friction and wear effects to be related to substrate bias. WC+Co coatings have been shown to be effective wear‐resistant surfaces when applied by predetermined deposition parameters.
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81.40.Pq Friction, lubrication, and wear
68.55.-a Thin film structure and morphology
82.80.-d Chemical analysis and related physical methods of analysis

Identification of surface radicals by vibration spectroscopy: Reactions of C2H2, C2H4, and H2 on Pt (111)

H. Ibach and S. Lehwald

J. Vac. Sci. Technol. 15, 407 (1978); http://dx.doi.org/10.1116/1.569558 (9 pages) | Cited 34 times

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High‐resolution electron energy loss spectroscopy has been applied to study the adsorption of acetylene and ethylene on Pt (111) and the surface reactions of these adsorbates as a function of temperature and in the presence of chemisorbed hydrogen. Making use of the surface selection rule and the observed frequencies a rather detailed picture is developed about the chemical nature of the adsorption states and reaction intermediates. Below room temperature, acetylene rehybridizes so as to form one strong di/σ‐like bond to the surface and an additional bond to the surface with the remaining π orbital. Ethylene is essentially just di/σ bonded. Around room temperature, ethylene converts to a new chemical species which we identify to be ethylidene (CH3–CH=). Ethylidene is also formed from acetylene when the surface is first exposed to hydrogen, then to acetylene at low temperatures, and subsequently annealed to 350 K. The same result was obtained by exposing adsorbed acetylene to atomic hydrogen at 350 K. We further find that the hydrogenation of adsorbed acetylene to ethylidene proceeds via the intermediate –CH2–C≡ (2‐ethyl–1‐ylidine).
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
82.20.Hf Product distribution
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
68.35.Ja Surface and interface dynamics and vibrations

Abstract: High resolution electron spectroscopy on Mo, GaSe, and Al crystals

Y. Ballu

J. Vac. Sci. Technol. 15, 416 (1978); http://dx.doi.org/10.1116/1.569559 (1 page)

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73.20.-r Electron states at surfaces and interfaces
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
79.60.-i Photoemission and photoelectron spectra

Abstract: Theory of inelastic low‐energy electron scattering from oriented molecules

W. Ho, J. W. Davenport, and J. R. Schrieffer

J. Vac. Sci. Technol. 15, 416 (1978); http://dx.doi.org/10.1116/1.569560 (1 page)

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34.80.Gs Molecular excitation and ionization

Abstract: Determination of adatom interaction energies by a Monte Carlo calculation: Oxygen on W(110)

E. D. Williams, S. L. Cunningham, and W. H. Weinberg

J. Vac. Sci. Technol. 15, 417 (1978); http://dx.doi.org/10.1116/1.569584 (2 pages)

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68.35.Md Surface thermodynamics, surface energies

A study of the sorption of CO on W and Ni single‐crystal surfaces by ion scattering

W. Heiland, W. Englert, and E. Taglauer

J. Vac. Sci. Technol. 15, 419 (1978); http://dx.doi.org/10.1116/1.569585 (4 pages) | Cited 5 times

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Helium ion backscattering is used to study the sorption of CO on W(100), Ni(110), and Ni(111) surfaces. It is concluded that the CO molecular axis is oriented normal to the Ni(110) and Ni(111) surfaces. The molecular orientation of CO on W(100) is more complicated, depending on the temperature. No orientation for CO molecules can be obtained at room temperature while at higher temperatures, CO appears to be either oriented parallel to the surface or dissociated.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Molecular‐beam apparatus for the study of gas–surface interactions

M. J. Cardillo, C. S. Y. Ching, E. F. Greene, and G. E. Becker

J. Vac. Sci. Technol. 15, 423 (1978); http://dx.doi.org/10.1116/1.569586 (6 pages) | Cited 9 times

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An ultrahigh vacuum apparatus has been developed to study the dynamics of gas–surface interactions utilizing modulated supersonic molecular‐beam techniques, angle‐resolved mass spectrometry, Auger electron spectroscopy, and low‐energy electron diffraction. Nearly monoenergetic beams of atoms and molecules in the form of narrow pulses or square waves are sent with a variable incident angle at a crystal. The wave forms of the scattered species or reaction products are monitored as a function of desorption or reflection angle. The initial experiments have examined the scattering of atoms and simple molecules from a Pt(111) surface. The results are in the form of angular and time‐of‐flight distributions for a range of incident beam energies, angles, and crystal temperatures.
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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
07.30.Hd Vacuum testing methods; leak detectors
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques

Precursor adsorption of O2 on tin and the activation energy for chemisorption

G. Chottiner and R. E. Glover

J. Vac. Sci. Technol. 15, 429 (1978); http://dx.doi.org/10.1116/1.569587 (4 pages) | Cited 2 times

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Condensation of a thick layer of O2 on Sn at 5 K causes an increase in resistance corresponding to a loss of metallic conductivity by less than 0.1 Å of Sn. The small magnitude must mean that oxygen is initially adsorbed in a molecular physisorbed state since tying up even one Sn conduction electron per surface atom in chemical bonds would cause a resistance increase more than 10 times that observed. When warmed above 13 K the resistance of the oxygen‐covered Sn films increases irreversibly with time, a change we attribute to chemisorption. The rate increases with increasing temperature and decreases as a total change corresponding to removal of 11 Å of Sn is approached. Analysis of the data for oxidation thicknesses between 1.5 and 8 Å gives consistent values for an activation energy of 0.035 eV.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
81.05.Bx Metals, semimetals, and alloys
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Determination of adsorbate bond geometry using photoemission

J. W. Davenport

J. Vac. Sci. Technol. 15, 433 (1978); http://dx.doi.org/10.1116/1.569588 (7 pages) | Cited 9 times

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It has been known for some time that angle‐resolved photoemission can give in principle a great deal of information about the valence states of adsorbed species. Recently this technique has been used to determine the orientation of CO on Ni, and Cu and NO on Ni. The reasons for this success are three: (1) a tunable, polarized light source, (2) an energy analyzer which could be positioned arbitrarily with respect to the sample and the light source, and (3) a theory of photoemission which is sufficiently accurate that the variations in intensity with molecular orientation could be predicted. In this paper I discuss the theoretical aspects, and in particular, assess the likelihood that similar experiments can be analyzed for other molecules to yield geometry. Certain results which follow from symmetry are given and multiple scattering calculations on CO and NiCO are compared with data.
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79.60.Jv Interfaces; heterostructures; nanostructures
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
31.70.Dk Environmental and solvent effects

Atomic and electronic structure of semiconductor surfaces

K. C. Pandey

J. Vac. Sci. Technol. 15, 440 (1978); http://dx.doi.org/10.1116/1.569589 (8 pages) | Cited 11 times

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The electronic structure of surfaces, which can be determined by various electron/ion spectroscopies including ultraviolet photoemission spectroscopy (UPS), is dependent on the surface atomic geometry. Thus, it is possible to determine the surface atomic structure via structure‐dependent theoretical analyses of these experimental spectra. Because of the complexity of such systems, a simple but accurate theoretical scheme is required. We show that the valence electronic states and atomic structures of semiconductor surfaces—both clean and with chemisorbed species as well as relaxed and/or reconstructed—can be determined using a tight‐binding model. Such calculations together with UPS data show that the annealed Si(111)7×7 surface contains about 25% vacancies. For GaAs(110), we have found tha the Ga atoms move into, and As atoms move out of the surface with small bond length distortions so that a plane through them makes an angle of about 20° with the surface. We show that H chemisorbed on Si(111) has two distinct structural phases: a monohydride phase at low coverages, and a rather unexpected trihydride phase at high coverages.
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68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
73.20.-r Electron states at surfaces and interfaces
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
79.60.Jv Interfaces; heterostructures; nanostructures

Abstract: Review of ion scattering methods for surface structure determination

L. C. Feldman

J. Vac. Sci. Technol. 15, 448 (1978); http://dx.doi.org/10.1116/1.569590 (1 page)

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68.37.-d Microscopy of surfaces, interfaces, and thin films

Abstract: Surface EXAFS: Geometry and bond length of I adsorbed on Ag (111)

P. H. Citrin, P. Eisenberger, and R. C. Hewitt

J. Vac. Sci. Technol. 15, 449 (1978); http://dx.doi.org/10.1116/1.569591 (1 page) | Cited 1 time

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61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
79.20.Fv Electron impact: Auger emission
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Solute segregation in iron‐based alloys

C. J. McMahon and L. Marchut

J. Vac. Sci. Technol. 15, 450 (1978); http://dx.doi.org/10.1116/1.569592 (17 pages) | Cited 21 times

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Segregation of metalloid impurities to grain boundaries of iron and its alloys can produce brittle intergranular cracking under a variety of external conditions. This set of phenomena is reviewed in terms of: segregation in dilute iron–metalloid binary alloys, interactions of metalloid elements with other solutes to enhance or retard segregation, the thermodynamics of segregation in binary and ternary alloys, the use of Auger electron spectroscopy for analysis of fracture surfaces and for studies of segregation to free surfaces, and the effects of segregation on mechanical behavior. The derivation of the general equations of segregation in a ternary regular solution from the Guttmann analysis is given in the Appendix.
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81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
64.75.-g Phase equilibria
62.20.M- Structural failure of materials
81.30.Mh Solid-phase precipitation

Orientation dependence of surface segregation in a dilute Ni–Au alloy

W. C. Johnson, N. G. Chavka, R. Ku, J. L. Bomback, and P. P. Wynblatt

J. Vac. Sci. Technol. 15, 467 (1978); http://dx.doi.org/10.1116/1.569593 (3 pages)

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Surface segregation theory admits that the degree of surface enrichment depends on surface orientation through the anisotropy of surface properties such as surface energy. This prediction was tested by determining the surface composition of several grains of different surface orientation in a polycrystalline Ni–Au alloy foil. A scanning Auger microprobe provided Auger point analyses which were used to determine the surface segregation characteristics of individual (randomly oriented) grains, while selected area electron channeling patterns, obtained with a scanning electron microscope, allowed the surface orientation of each grain to be determined. A strong anisotropy of gold surface enrichment was observed; for example,the gold surface concentration at 700°C varied by as much as an order of magnitude over the range of surface orientations investigated. A plot of the variation in surface composition within the standard stereographic triangle showed trends that are comparable with the known anisotropy of surface energy in fcc metals. It is concluded that the coupling of the above experimental techniques provides a powerful tool for the study of such phenomena.
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64.75.-g Phase equilibria
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Abstract: Grain boundary segregation of an Al–Zn–Mg ternary alloy

J. M. Chen, T. S. Sun, R. K. Viswanadham, and J. A. S. Green

J. Vac. Sci. Technol. 15, 470 (1978); http://dx.doi.org/10.1116/1.569594 (1 page) | Cited 1 time

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61.72.Mm Grain and twin boundaries

Abstract: Surface segregation in alloys: Existence of surface miscibility gaps within regular solution theory

C. R. Helms

J. Vac. Sci. Technol. 15, 470 (1978); http://dx.doi.org/10.1116/1.569595 (2 pages) | Cited 1 time

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64.75.-g Phase equilibria

Abstract: Prospects for a quantitative theory of surface segregation

James J. Burton

J. Vac. Sci. Technol. 15, 472 (1978); http://dx.doi.org/10.1116/1.569596 (1 page)

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68.35.Md Surface thermodynamics, surface energies
64.75.-g Phase equilibria

Abstract: Surface site geometry and diffusion characteristics of single Ni atoms on W (111)

Peter G. Flahive and William R. Graham

J. Vac. Sci. Technol. 15, 472 (1978); http://dx.doi.org/10.1116/1.569597 (2 pages)

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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
68.37.Vj Field emission and field-ion microscopy

Surface diffusion of carbon on (111) platinum

Michael T. Martin and John B. Hudson

J. Vac. Sci. Technol. 15, 474 (1978); http://dx.doi.org/10.1116/1.569598 (4 pages) | Cited 5 times

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An Auger electron spectrometric technique has been employed to measure the diffusivity of carbon atoms on an otherwise clean Pt(111) surface. The technique used was essentially a classical mass transport method, in which the rate the migration of carbon atoms out of a circular surface region initially containing a monolayer of adsorbed carbon was measured by Auger electron spectrometry. The diffusivity D can be characterized by an Arrhenius equation D=D0exp(—ΔH∗/RT) in which D0=0.2 cm2/s and ΔH∗=31±4 kcal/mol. Additional data are presented to demonstrate the self‐consistency of the experimental method used.
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66.30.J- Diffusion of impurities

Self‐consistent electronic densities and adhesive energies at metallic interfaces

John Ferrante and John R. Smith

J. Vac. Sci. Technol. 15, 478 (1978); http://dx.doi.org/10.1116/1.569599 (1 page)

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61.50.Lt Crystal binding; cohesive energy
46.55.+d Tribology and mechanical contacts

Abstract: Spin‐orbital electronegativity and catalytic activity

K. H. Johnson

J. Vac. Sci. Technol. 15, 478 (1978); http://dx.doi.org/10.1116/1.569600 (1 page)

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82.30.Vy Homogeneous catalysis in solution, polymers and zeolites
68.03.Fg Evaporation and condensation of liquids

Purposeful modification by gas adsorption of atomically clean iron surfaces at room temperature and characterization by 21.2‐eV photoemission

Carl Russo and Roy Kaplow

J. Vac. Sci. Technol. 15, 479 (1978); http://dx.doi.org/10.1116/1.569601 (6 pages)

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We have previously explored purposeful exposure of an atomically clean surface to controlled environments as a technique for obtaining surfaces with desired properties. The incorporation of nitrogen into atomically clear iron is an example of beneficial clean surface modification and results in enhancement of resistance to corrosion at room temperature in dry and moist air, relative to initially air exposed samples. The in situ 21.2‐eV photoelectron spectroscopy, using a windowed discharge lamp and residual gas analysis were performed on clear iron and iron in the course of N2 and H2O exposures as well as N2–O2 and N2–H2O sequential exposures. These room‐temperature UPS adsorption studies, which covered pressures from 5×10−8 to 0.5 Torr indicate the following: dissociative adsorption of N2 and H2O; molecular H2O adsorption at pressures greater than 0.05 Torr; the dissociative adsorption of oxygen on nitrogen‐treated surfaces (as on untreated surfaces); and a complex reaction between preadsorbed nitrogen and water vapor. The in situ adsorption results are consistent with spin orbital electronegativity concepts together with electronic structure calculations in the self‐consistent field‐Xα approximation. The Fe–N2–H2O study is consistent with a proposed model in which the inhibition of molecular water vapor adsorption on nitrogen‐treated iron is responsible for the resistance to corrosion noted.
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81.05.Bx Metals, semimetals, and alloys
79.60.-i Photoemission and photoelectron spectra
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Electronic orbitals of Se bonded to Ni(100)

H. Froitzheim and H. D. Hagstrum

J. Vac. Sci. Technol. 15, 485 (1978); http://dx.doi.org/10.1116/1.569602 (3 pages)

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New angle‐integrated UPS spectra are presented at different angles of light incidence for NeI radiation on Ni(100) c (2×2)Se. These spectra show that a Se‐derived orbital lies in the energy range of the Ni d band as suggested by Fisher. The corresponding INS spectrum is also given and discussed. It is shown that the present Ni sample produces a two‐domain c (2×5)Se structure at one‐quarter monolayer as opposed to the p (2×4)Se structure observed on earlier samples.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
79.60.Jv Interfaces; heterostructures; nanostructures
73.20.-r Electron states at surfaces and interfaces

Surface resonances and the oxidation of single‐crystal aluminum

R. Z. Bachrach, S. A. Flodström, R. S. Bauer, S. B. M. Haström, and D. J. Chadi

J. Vac. Sci. Technol. 15, 488 (1978); http://dx.doi.org/10.1116/1.569603 (6 pages) | Cited 6 times

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Valence‐band photoemission spectra have been studied on single‐crystal aluminum faces using polarized sychrotron radiation. New intrinsic and oxygen‐related extrinsic surface resonance features are observed within 5 eV of the Fermi level. These surface resonances are correlated with oxygen uptake on the (100), (110), and (111) faces as observed in both valence and core‐level spectroscopy. Considerable face dependence to the oxidation is shown. Although aluminum is a free‐electron‐like metal, its surface behavior on single‐crystal faces shows effects due to localized charge.
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81.05.Bx Metals, semimetals, and alloys
79.60.-i Photoemission and photoelectron spectra
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Abstract: An experimental and theoretical study of the surface resonances on the (100) face of W and Mo

Shang‐Lin Weng

J. Vac. Sci. Technol. 15, 494 (1978); http://dx.doi.org/10.1116/1.569604 (1 page) | Cited 1 time

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73.20.-r Electron states at surfaces and interfaces

Abstract: Adsorption of oxygen on Cu(100)−A study by angularly resolved ultraviolet photoemission spectroscopy (ARUPS)

D. T. Ling, J. N. Miller, P. A. Pianetta, D. L. Weissman, I. Lindau, and W. E. Spicer

J. Vac. Sci. Technol. 15, 495 (1978); http://dx.doi.org/10.1116/1.569605 (2 pages)

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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Auger and photoelectron study of codeposited sulfur and oxygen layers on silver (111)

Gary G. Tibbetts and James M. Burkstrand

J. Vac. Sci. Technol. 15, 497 (1978); http://dx.doi.org/10.1116/1.569606 (5 pages) | Cited 6 times

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When oxygen and sulfur are codeposited on a silver surface, the sulfur L2,3MM Auger spectrum is altered significantly from that obtained when sulfur alone is deposited. Besides a chemical shift due to the observed 6.6‐eV sulfur L2,3 binding energy increase on coadsorption with oxygen, the oxygen L1 core level and a hybridized sulfur level in the valence band participate in the sulfur Auger process, introducing new Auger peaks similar to those present in surfaces containing SO4= groups. Electron bombardment of this film preferentially desorbs oxygen and alters the Auger spectrum back to one characteristic of films of sulfur alone on silver. These Auger spectra are analyzed on the basis of a model which uses experimentally determined initial states and small final‐state effects.
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82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
79.60.Jv Interfaces; heterostructures; nanostructures
32.80.Hd Auger effect (including Coster-Krönig transitions)
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Elastic and inelastic contributions to secondary electron yield structure

M. L. den Boer, P. I. Cohen, and Robert L. Park

J. Vac. Sci. Technol. 15, 502 (1978); http://dx.doi.org/10.1116/1.569455 (4 pages) | Cited 1 time

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The secondary electron yield of solid surfaces contains weak but complicated structure, which is greatly enhanced by differentiation with respect to primary electron energy. Auger electron appearance potential features, corresponding to yield changes due to core level excitations, and diffraction features are the major contributions to this structure. The magnitude of the diffraction features decreases with primary energy and depends strongly on temperature and surface order. Surprisingly, even for polycrystalline materials the diffraction features extend out to about 400 eV and completely obscure appearance potential features in this region. We have measured the energy distribution of electrons contributing to each of these kinds of features. The diffraction structure is due almost entirely to elastic electrons while the appearance potential peaks result primarily from electrons with energy less than 30 eV. This difference can be exploited using a double modulation scheme with four‐grid LEED optics to separate the two kinds of features. This extends the useful range of Auger electron appearance potential spectroscopy down to energies below 200 eV.
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79.20.Fv Electron impact: Auger emission
79.20.Hx Electron impact: secondary emission

Quasisimultaneous SIMS, AES, and XPS investigations of the oxidation of Mo, Ti, and Co in the monolayer range

A. Benninghoven, O. Ganschow, and L. Wiedmann

J. Vac. Sci. Technol. 15, 506 (1978); http://dx.doi.org/10.1116/1.569456 (4 pages) | Cited 2 times

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The oxidation of Mo, Ti, and Co at oxygen exposures up to several hundred Langmuirs has been investigated by combination of static SIMS, ’’static’’ AES (i.e. direct counting of the N (E) spectrum at low primary electron current), and XPS. The proportionally of the O(1s) and O(KLL) signals allows one to establish a coverage scale in the submonolayer range. For Mo and Ti, saturation of the Auger and O(1s) signals is reached after 4 and 9 L, respectively. The beginning surface oxidation is indicated by the successive appearance of the compound secondary ions MeO±n at about 2−20 L. For Ti, the in‐depth growth of the ’’oxide’’ is indicated at exposures above 8 L by the chemical shift of the Ti 2p levels, whereas for Mo no shift of the Mo(3d) levels is present up to 1000 L. Co behaves similarly to Ti, except for the higher oxygen doses needed for saturation and an additional phase at 0−5 L, which is characterized by enhanced Co+, CoO+, and O− emission, a break in the O(1s)vs exposure curve, and an initial O(1s) level with different binding energy.
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81.05.Bx Metals, semimetals, and alloys
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Abstract: Atomic chemisorption on simple metals: Chemical trends and core‐hole relaxation effects

N. D. Lang and A. R. Williams

J. Vac. Sci. Technol. 15, 510 (1978); http://dx.doi.org/10.1116/1.569457 (1 page)

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68.43.-h Chemisorption/physisorption: adsorbates on surfaces

NVV Auger spectra from W(100)

S. P. Withrow, P. E. Luscher, F. M. Propst, and W. H. Weinberg

J. Vac. Sci. Technol. 15, 511 (1978); http://dx.doi.org/10.1116/1.569458 (7 pages)

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The NVV Auger spectrum from a clean W(100) surface has been measured in the second derivative, d2N (E)/dE2, mode to enhance fine structure. This measurement is compared with spectra generated from both the self‐convolution of the tungsten valence‐band bulk density of states (obtained from a relativistic APW energy band calculation) and a ’’restricted convolution’’ in which only transitions involving electrons from the same valence energy are allowed. The restricted convolution for a model of the Auger process in which both N6VV and N7VV transitions contribute offers the best match of theory and experiment. No distinct evidence of Auger emission involving the surface resonance present on W(100) is observed. Effects of H2 and O2 adsorption on the Auger spectrum of the W(100) surface are reported.
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79.20.Fv Electron impact: Auger emission
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
71.20.-b Electron density of states and band structure of crystalline solids

X‐ray photoelectron spectroscopy with x‐ray photons of higher energy

C. D. Wagner

J. Vac. Sci. Technol. 15, 518 (1978); http://dx.doi.org/10.1116/1.569459 (6 pages) | Cited 26 times

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There have been few studies using ionizing photons higher in energy than Al Kα (1487 eV). However, characteristic x rays such as Au Mα (2123 eV) and Ag Lα (2984 eV) are nearly as narrow in energy, and can provide deeper core photoelectron lines and their companion core‐type Auger lines in the spectra of 26 elements that otherwise cannot be recorded. Such data are of special value in identifying chemical states by the two‐dimensional approach. This involves plotting Auger kinetic energy against photoelectron kinetic energy. The Auger Parameter is the difference between these two energies. Chemical shifts in the Auger parameter provide information on polarization effects in the medium. New data are shown for solid compounds of silicon, sulfur, bromine, and tungsten, obtained with Au Mα x rays. Other reported data obtained with x rays ≳1500 eV are included for comparison. The data for the eighteen compounds of tungsten show considerable variation in chemical shifts in the M5N7N7 Auger line as well as those of the 3d5/2 photoelectron line; neither of these lines is accessible by Al Kα radiation.
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79.60.-i Photoemission and photoelectron spectra
32.80.Hd Auger effect (including Coster-Krönig transitions)
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Abstract: Chlorine and carbon monoxide chemisorption on semiconductors: Synchrotron radiation photoemission

Toshio Sakurai, G. Margaritondo, J. E. Rowe, and H. D. Hagstrum

J. Vac. Sci. Technol. 15, 524 (1978); http://dx.doi.org/10.1116/1.569460 (1 page)

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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
79.60.Jv Interfaces; heterostructures; nanostructures

Interface states at the Ga–GaAs interface

R. Z. Bachrach and A. Bianconi

J. Vac. Sci. Technol. 15, 525 (1978); http://dx.doi.org/10.1116/1.569461 (4 pages) | Cited 4 times

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A variable‐excitation energy photoemission study has been made of the occupied states near the Ga–GaAs (110) interface as the interface is formed. Using a combination of valence and core‐level spectroscopy, new aspects of the interface electronic structure have been deduced. Using valence‐band spectroscopy, interface states are found to appear as the Ga film is built up. Using core‐level spectroscopy, one finds chemical shifts in both the Ga and As 3d levels. The As shift indicates that surface charge redistribution from the As to the Ga occurs at the interface.
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73.40.Ns Metal-nonmetal contacts
79.60.-i Photoemission and photoelectron spectra

Surface photovoltage spectroscopy of defects and impurities in trigonal selenium

L. J. Brillson and C. H. Griffiths

J. Vac. Sci. Technol. 15, 529 (1978); http://dx.doi.org/10.1116/1.569462 (4 pages) | Cited 2 times

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The bulk electronic structure associated with defects and impurities in trigonal selenium has been determined by surface photovoltage spectroscopy. Surface and bulk photovoltage contributions were separated by varying the UHV surface conditions as monitored by Auger electron spectroscopy. Lattice defects formed during crystal growth exhibited deep and shallow bulk traps, identical to mechanical damage features. Ar+ bombardment produced surface defect levels in the band gap at the same bulk defect energies. No intrinsic surface states were measured on the clean (101̄0) face. Bulk Cl and As dopants in trigonal selenium produced additional discrete levels in the band gap at energies consistent with known transport properties. Since the trigonal selenium surface is not strongly reactive, bulk lattice defects rather surface states dominate the surface electronic structure.
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73.20.Hb Impurity and defect levels; energy states of adsorbed species
72.40.+w Photoconduction and photovoltaic effects

Abstract: Charge transfer in ZnO surfaces in the pressure of photosensitizing dyes

J. Lagowski, H. C. Gatos, and C. L. Balestra

J. Vac. Sci. Technol. 15, 533 (1978); http://dx.doi.org/10.1116/1.569463 (1 page)

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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Chemisorbed phases of O2 on TiO2 and SrTiO3

Victor E. Henrich, G. Dresselhaus, and H. J. Zeiger

J. Vac. Sci. Technol. 15, 534 (1978); http://dx.doi.org/10.1116/1.569464 (4 pages) | Cited 13 times

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We have investigated the chemisorption of O2 on TiO2 and SrTiO3 surfaces by using ultraviolet photoemission difference spectroscopy. Both nearly perfect surfaces and surfaces having a high density of defects associated with filled Ti(3d) surface states were studied. On all surfaces low O2 exposures produced an initial adsorbed phase, with a sticking coefficient of 0.2–1, that yields a difference spectrum consisting of two peaks separated by 2.5 eV. The location of these peaks corresponds closely to the valance‐band photoemission structure of the substrate, suggesting that the chemisorbed phase consists of O2− ions. For surfaces having initially filled Ti(3d) surface states, formation of this phase is accompanied by charge transfer from the substrate. With increasing exposure, a second adsorbed phase, with a sticking coefficient of 10−3 or less, is formed on some surfaces. This phase exhibits a sharp peak about 2 eV below the bottom of the substrate valence band and a broad peak overlapping the valance band.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
73.20.Hb Impurity and defect levels; energy states of adsorbed species
79.60.Jv Interfaces; heterostructures; nanostructures

Surface photovoltage experiments on SrTiO3 electrodes

J. G. Mavroides and D. F. Kolesar

J. Vac. Sci. Technol. 15, 538 (1978); http://dx.doi.org/10.1116/1.569465 (4 pages) | Cited 7 times

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Electronic surface states play a significant role in charge transfer between the electrolyte and the n‐type SrTiO2 semiconducting electrodes used in the photoelectrolysis of water. To clarify the role of these states, we have measured the wavelength response of the photovoltage developed between the SrTiO3 surface and a vibrating Au reference electrode, both in vacuum and in a water vapor ambient. When the SrTiO3 is exposed to sub‐band‐gap radiation, the amplitude and sign of the photovoltage vary with photon energy. Significant changes in the spectrum result from the introduction of water vapor. The energy‐dependent structure is interpreted in terms of photon‐induced electronic transitions between the states near the surface and conduction or valence band states.
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73.20.-r Electron states at surfaces and interfaces
82.30.Fi Ion-molecule, ion-ion, and charge-transfer reactions
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
72.40.+w Photoconduction and photovoltaic effects

Abstract: Hydrogenation of CO on rhodium and iron crystal surfaces

G. A. Somorjai

J. Vac. Sci. Technol. 15, 542 (1978); http://dx.doi.org/10.1116/1.569466 (1 page)

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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
81.05.Bx Metals, semimetals, and alloys

Ultraviolet photoemission studies of formaldehyde and related molecules adsorbed on Ru(110)

Galen B. Fisher, Theodore E. Madey, and John T. Yates

J. Vac. Sci. Technol. 15, 543 (1978); http://dx.doi.org/10.1116/1.569467 (5 pages)

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The adsorption of formaldehyde (H2CO), hydrogen, and carbon monoxide on Ru(110) has been studied using angle‐integrated ultraviolet photoemission spectroscopy (UPS) and temperature programmed desorption (TPD). The UPS spectra for low exposures of H2CO at 80 K indicate that H2CO dissociates to a substantial degree. These spectra are compared with UPS spectra for the sequential adsorption of hydrogen and CO. Whereas there are similarities between these spectra, the differences in the UPS, work function change, and TPD results are sufficient to suggest that a portion of the dissociated H2CO may exist as a surface molecular complex containing H and CO. This is apparently the first reported example, based on a UPS study, of an oxygen‐containing organic molecule which dissociates upon adsorption on a metal surface at 80 K. For high exposures at 80 K, adsorption of a condensed layer of molecular H2CO is observed.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
79.60.Jv Interfaces; heterostructures; nanostructures
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Abstract: Characterization of adsorbed hydrocarbons by electron‐stimulated desorption

Theodore E. Madey and John T. Yates

J. Vac. Sci. Technol. 15, 548 (1978); http://dx.doi.org/10.1116/1.569468 (1 page)

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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)

Surface analysis by electron spectroscopy at high pressures

C. J. Powell

J. Vac. Sci. Technol. 15, 549 (1978); http://dx.doi.org/10.1116/1.569469 (4 pages)

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Surface analyses are now made by techniques such as Auger electron spectroscopy (AES), x‐ray photoelectron spectroscopy (XPS), and appearance potential spectroscopy (APS). These techniques utilize low‐energy electrons and have high surface sensitivity but cannot be used at high pressures [≳10−4 Torr(≳10−2 Pa)]. Optical techinques can be used at high pressures but their surface sensitivity is poor. It is proposed to combine these approaches by using the high‐pressure gas as a converter. Two situations are considered. First, variable‐energy x‐rays are used to produce variable‐energy photoelectrons from the gas which impinge on the sample; these electrons constitute a suitable source for APs. Second, the variable‐energy x‐rays produce photoelectrons from the sample (XPS) of variable energy; these electrons can be detected using the gas for APS. In both cases, the derivative of the x‐ray yield from the gas‐sample cell is measured as a function of incident x‐ray energy; features in the derivative spectrum can be correlated with the core levels of surface atoms of the sample. Design calculations based on x‐ray intensities from available sources indicate that the proposed method could only be useful for specialized applications.
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82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
79.60.-i Photoemission and photoelectron spectra
07.85.-m X- and γ-ray instruments

Abstract: Methanation over polycrystalline Ni and Pt foils

J. A. Schwarz and R. S. Polizzotti

J. Vac. Sci. Technol. 15, 553 (1978); http://dx.doi.org/10.1116/1.569470 (1 page)

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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Kinetics of thermal desorption and thermal conversion of adsorbates: AES studies

G. Robertshaw and P. J. Estrup

J. Vac. Sci. Technol. 15, 554 (1978); http://dx.doi.org/10.1116/1.569471 (5 pages) | Cited 2 times

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A surface analysis technique, called ’’thermal conversion spectroscopy’’ (TCS), has been developed which employs Auger electron spectroscopy (AES) to measure adsorbate coverage as a continuous function of temperature. The technique is expected to be particularly useful in studies of the kinetics of surface processes which involve a conversion from one adsorbate state to another without causing any corresponding change in the gas phase. To evaluate the technique it has been applied to the desorption of CO from a W substrate and a direct comparison has been made with conventional thermal desorption spectrometry (TDS) done with a mass spectrometer. The Auger detection method is found to give the lower signal‐to‐noise ratio but the resolution is relatively high since complications arising from sample thermal gradients and overall vacuum system response (pumping speed, wall effects, etc.) are absent. By monitoring the carbon Auger spectrum, data analogous to TDS curves have been obtained for the thermally induced decomposition of ethylene on tungsten. Following saturation at room temperature, the TCS curve almost coincides with the TDS curve for H2. When ethylene and oxygen are coadsorbed the decomposition rate is significantly lower. The implications for the conversion mechanism are discussed briefly.
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Carbon layer formation on the Pt (111) surface as a function of temperature

J. C. Hamilton and J. M. Blakely

J. Vac. Sci. Technol. 15, 559 (1978); http://dx.doi.org/10.1116/1.569472 (4 pages) | Cited 2 times

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The (111) surfaces of carbon‐doped Pt single crystals were studied using LEED and Auger spectroscopy to determine the characteristics of carbon segregation of platinum. Carbon was observed to appear on the surface reversibly when the crystals were cooled. Observations of coverage versus temperature, carbon Auger peak shapes, and LEED patterns indicate that the appearance of carbon on Pt(111) can be explained solely by precipitation and that segregation of carbon does not occur on this surface to within the limit of detectability. The fact that no detectable segregation is observed indicates that single carbon atoms are not appreciably more strongly bound on the Pt(111) surface than in the interior of the crystal and that the bonding of a single graphite layer to the Pt(111) surface is weaker than the interlayer bonding of carbon in bulk graphite.
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68.55.-a Thin film structure and morphology
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Chlorine adsorption on silver surfaces

Yung‐Yi Tu and J. M. Blakely

J. Vac. Sci. Technol. 15, 563 (1978); http://dx.doi.org/10.1116/1.569473 (5 pages) | Cited 2 times

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The properties and structure of adsorbed chlorine layers on clean silver surfaces have been studied. On the Ag(111) surface, isobars over the temperature range from ∠300 to ∠900 K have been obtained using Auger electron spectroscopy. A model dependent, initial heat of adsorption of ∠50 kcal/mol was obtained. Structural observations using LEED showed that an epitaxial layer of AgCl(111) was formed. Electron impact desorption measurements give a desorption cross section for chlorine. On the Ag(110) surface a set of isotherms was obtained and the model independent isosteric initial heat of adsorption was also calculated to be ∠50 kcal/mol.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Chemisorption of CO on Pd particles supported on mica

M. Thomas, J. T. Dickinson, H. Poppa, and G. M. Pound

J. Vac. Sci. Technol. 15, 568 (1978); http://dx.doi.org/10.1116/1.569474 (4 pages) | Cited 1 time

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A new UHV technique is presented for evaluating the adsorption–desorption properties of UHV vapor‐deposited metal particles supported on insulating substrates. Desorption studies of CO from particulate and continuous Pd films supported on mica were performed. The desorption results indicate that (1) the CO desorption energies from the deposited metals are much lower than those from bulk single crystals. (2) two desorption states were found for the vapor‐deposited films, and (3) the lower energy desorption peak of the vapor‐deposited films is coverage dependent with an activation energy of 27.25–2.85σ kcal/mol. Possible reasons for the difference between previously reported CO desorption studies on bulk substrates and the present results are discussed.
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
07.30.-t Vacuum apparatus
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Abstract: Technique for studying chemisorption on substrates with complex band structures

S. L. Cunningham, W. H. Weinberg, and V. M. Tapilin

J. Vac. Sci. Technol. 15, 572 (1978); http://dx.doi.org/10.1116/1.569475 (2 pages)

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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Abstract: Electronic surface resonances and crystal surface structure

E. G. McRae and C. W. Caldwell

J. Vac. Sci. Technol. 15, 574 (1978); http://dx.doi.org/10.1116/1.569476 (1 page)

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61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)

Angular‐resolved UPS studies of the chemisorption of ethylene and acetylene on nickel (100)

K. Horn, A. M. Bradshaw, and K. Jacobi

J. Vac. Sci. Technol. 15, 575 (1978); http://dx.doi.org/10.1116/1.569477 (5 pages) | Cited 8 times

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In photoemission from surfaces, simple selection rules govern the relationship between normal exit emission and the symmetry of the initial state wave function. UPS measurements on CO/Ni(100) with unpolarized light have already shown that the dependence of normal emission intensity on photon angle of incidence can be used for the assignment of adsorbate molecular orbitals. In the present paper the method is extended to the (√2×√2) R45 structures formed by C2H2 and C2H4 on Ni(100) at 80 K. Heating the surfaces formed by the interaction at low temperature results in pronounced changes in the UPS spectrum, which in turn indicates changes in the chemical nature of the adlayers. An ordered surface structure is, however, retained until above room temperature.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
79.60.Jv Interfaces; heterostructures; nanostructures
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Subsurface atomic displacements at the GaAs(110) surface

A. Kahn, E. So, P. Mark, and C. B. Duke

J. Vac. Sci. Technol. 15, 580 (1978); http://dx.doi.org/10.1116/1.569630 (5 pages) | Cited 5 times

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LEED IS (intensity–momentum transfer) data has been used to verify atomic displacements in the first subsurface layer of GaAs(110). IS profiles averaged over a range of incidence (ϑ) and azimuthal (ϕ) angles, subject to constant S, data for selected values of ϑ and ϕ, and similar IS profiles computed from kinematical calculations are intercompared to assess the relative importance of inadequate data averaging and variations of geometric parameters. Preferred atomic position parameters in the terminating region of the lattice are given.
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68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)

Oxygen uptake on epitaxial PbTe(111) surfaces

T. S. Sun, N. E. Byer, and J. M. Chen

J. Vac. Sci. Technol. 15, 585 (1978); http://dx.doi.org/10.1116/1.569631 (5 pages) | Cited 2 times

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The uptake of oxygen on Ar+‐cleaned (111) surfaces of PbTe epitaxial films was studied by means of UPS and XPS. Two distinct stages of uptake process were observed and they were separated by a phaselike change at an exposure of 105 L. The first stage, characteristic of an adsorption process, has a high oxygen uptake rate. In this stage, weak bonding between oxygen and the substrate is suggested by the observation of the relatively narrow linewidth of the Pb 5d5/2 core level. The most important feature, however, is the lowering of the Fermi level with oxygen coverage, which confirms the band bending model developed by previous studies, based on electrical measurements. The second stage, characteristic of an oxidation process, has a lower uptake rate. Strong bonds between oxygen and individual Pb and Te ions appear to prevail in this stage, as is evident from the broadening of the Pb 5d5/2 level and the appearance of the Te oxide species in the XPS spectra. The Fermi level stops lowering and in fact rises slightly at high oxygen coverages.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
73.20.Hb Impurity and defect levels; energy states of adsorbed species
81.65.-b Surface treatments
68.55.-a Thin film structure and morphology

Abstract: Chemisorption of carbon monoxide on the (110) surface of iridium

James L. Taylor and W. Henry Weinberg

J. Vac. Sci. Technol. 15, 590 (1978); http://dx.doi.org/10.1116/1.569632 (1 page)

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68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Temperature effects in polarized low‐energy electron scattering from solids and liquids

W. N. Unertl

J. Vac. Sci. Technol. 15, 591 (1978); http://dx.doi.org/10.1116/1.569633 (4 pages) | Cited 1 time

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The effects of temperature on the polarization of low‐energy electrons scattered from surfaces of liquids, polycrystals, and single crystals are discussed. The polarization of the single scattering component of the intensity is shown to be independent of temperature, whereas that of the multiple scattering intensity is temperature dependent. Differences between polarizations observed for electron scattering from free atoms and from polycrystals and liquids are qualitatively explained and a quantitative theory is outlined. The implications for polarized low‐energy electron diffraction from single‐crystal surfaces are also discussed.
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61.05.jd Theories of electron diffraction and scattering
79.20.Kz Other electron-impact emission phenomena
34.80.Bm Elastic scattering

Abstract: Electronic structure and catalytic activity of coordinatively unsaturated platinum sites

A. C. Balazs and K. H. Johnson

J. Vac. Sci. Technol. 15, 595 (1978); http://dx.doi.org/10.1116/1.569634 (1 page)

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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
73.20.-r Electron states at surfaces and interfaces
82.30.Vy Homogeneous catalysis in solution, polymers and zeolites

LEED structure analysis of a p (2×2) chemisorbed layer of CO on Ti(0001)

H. D. Shih, F. Jona, D. W. Jepsen, and P. M. Marcus

J. Vac. Sci. Technol. 15, 596 (1978); http://dx.doi.org/10.1116/1.569635 (4 pages) | Cited 3 times

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Exposure of a clean Ti(0001) surface to CO gas gives rise to the formation of first a p (2×2) and then a 1×1 LEED pattern. An intensity analysis of the p (2×2) phase has been carried out using six integral‐order and four fractional‐order spectra. Several models involving the CO molecule with axis normal to the surface have been tested with negative results. Fair agreement between observed and calculated intensities has been obtained for models involving C and O atoms (both 1/4 monolayer) in the same plane parallel to the surface and either both in the ’’fcc’’ or both in the ’’hcp’’ threefold symmetrical hollows. The former model is better than the latter, but for neither is the agreement wholly satisfactory. Experience with the N/Ti system suggests that the ’’correct’’ model may involve formation of an underlayer. This model, however, cannot be tested with our computer programs at the present time.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Reconstruction of stepped nickel surfaces

H. V. Thapliyal and J. M. Blakely

J. Vac. Sci. Technol. 15, 600 (1978); http://dx.doi.org/10.1116/1.569636 (6 pages) | Cited 8 times

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The morphology of stepped surfaces of nickel has been studied using LEED and AES. LEED study reveals some morphological transitions which are reversible with temperature cycling. At high temperatures the stepped surfaces have arrays of monoatomic height steps. At low temperatures an increase in ordering takes place for clean and carbon covered surfaces. For the case of clean surfaces, steps coalesce to form multiatom height steps. The surfaces are faceted in the presence of carbon as an adsorbate, while step coalescence is inhibited by sulfur adsorption. These transitions are believed to be caused by strong interaction among steps.
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68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
81.10.Aj Theory and models of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation

Abstract: Influence of refraction of p‐polarized light on photoemission from metallic surface states

A. Bagchi and R. G. Barrera

J. Vac. Sci. Technol. 15, 606 (1978); http://dx.doi.org/10.1116/1.569637 (1 page)

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73.20.-r Electron states at surfaces and interfaces
79.60.Bm Clean metal, semiconductor, and insulator surfaces
78.20.Jq Electro-optical effects

Intermolecular forces and kinetics of adsorption into a c (2×2) overlayer on (100) surface: H2S, C2H2, and C2H4 on Pt(100)

T. E. Fischer and S. R. Kelemen

J. Vac. Sci. Technol. 15, 607 (1978); http://dx.doi.org/10.1116/1.569638 (4 pages)

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Pt(100) surfaces, either in the 1×1 or the 5×20 structure, held at various temperatures were exposed to H2S, acetylene or ethylene gas in the 10−5 Pa (10−7 Torr) pressure range and the surface coverage ϑ was determined from the size of the C or S Auger signal as a function of exposure to the gas ϵ=Fpdt. Asymptotic saturation, ϑ=1 in the case o9f acetylene, was measured to correspond to 1 molecule/2 Pt surface atoms. Coadsorption measurements and LEED measurements justify the use of the same molecule density for ϑ=1 in the case of ethylene adsorption. All adsorbates formed a variously developed C (2×2) superstructure. The adsorption of acetylene and dissociation of H2S followed the Langmuir isotherm ϑ=1−exp(Sϵ) or dϑ/dE=S(1−ϑ). When the surfaces are exposed to ethylene, the adsorbed species in C2Hx, where the value of x depends on experimental condition. Exposure to ethylene yields the adsorption kinetics (1=ϑ) =constxϵ−1/3, or dϑ/dϵ=S(1−ϑ)4. We show that the adsorption kinetics of ethylene is a simple consequence of the c (2×2) overlayer formed by the absorbate and interpret the coexistence of Langmuir kinetics and a c (2×2) structure of the adsorbate layer in terms of the interlay of attraction to the surface and repulsion for adsorbed molecules.
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
34.20.-b Interatomic and intermolecular potentials and forces, potential energy surfaces for collisions
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Surface reflectance spectroscopy on low‐index planes of tungsten

M. A. Passler and P. J. Stiles

J. Vac. Sci. Technol. 15, 611 (1978); http://dx.doi.org/10.1116/1.569639 (5 pages)

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The fractional changes in optical reflectance for s and p polarization, ΔRs/Rs and ΔRp/Rp, have been determined for the adsorption of H2, O2, and CO on the low‐index planes of W. Structure in the spectra of ΔRs/Rs and ΔRp/Rp are very similar, implying that the microscopic corrections to the classical equations for ΔRp/Rp are small for photon energies 0.5–4.5 eV. Similarities in the spectra for the chemisorption of the different adsorbates on W(111) imply that the main effect is due to the mere presence of the adsorbate, rather than the identity of the adsorbate. It is possible that this lack of specificity can be explained by a surface relaxation upon chemisorption.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
79.60.Jv Interfaces; heterostructures; nanostructures
78.90.+t Other topics in optical properties, condensed matter spectroscopy and other interactions of particles and radiation with condensed matter (restricted to new topics in section 78)

Ni(100) with chalcogen overlayers: Theory for structures, force constants, binding energies, photoemission spectra; importance of final‐state multiplet splittings

Alfred B. Anderson

J. Vac. Sci. Technol. 15, 616 (1978); http://dx.doi.org/10.1116/1.569640 (3 pages)

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A theory combining Hellmann–Feynman electrostatic forces and one‐electron molecular orbital energies is used to determine spectroscopic properties for diatomic and surface nickel chalcogenides. The small cluster model for the surface is found adequate for all properties considered. The absorbate p photoemission bands are interpreted in terms of final‐state chalcogen atom multiplet splittings, opposed to previous studies which attributed the complicated spectra to unusual bonding interactions between the absorbate and substrate.
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73.20.-r Electron states at surfaces and interfaces
79.60.Jv Interfaces; heterostructures; nanostructures
36.40.-c Atomic and molecular clusters
71.20.-b Electron density of states and band structure of crystalline solids

LEED analysis of a Cu(110) surface

J. R. Noonan, H. L. Davis, and L. H. Jenkins

J. Vac. Sci. Technol. 15, 619 (1978); http://dx.doi.org/10.1116/1.569641 (3 pages) | Cited 3 times

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Experimental and calculated I–V profiles for the (0l̄) diffraction beam from a Cu(110) surface are presented and compared. Preliminary results of this comparison suggest that the outermost atomic layer is contracted by ∠10% relative to the bulk interlayer spacing, and there is some evidence that the second‐third layer spacing may be slightly contracted. In order to demonstrate the reproducibility of the data obtained in this investigation, degeneracies of beams related by symmetry are also illustrated.
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68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)

Oxidation of tin: An ESCA study

C. L. Lau and G. K. Wertheim

J. Vac. Sci. Technol. 15, 622 (1978); http://dx.doi.org/10.1116/1.569642 (3 pages) | Cited 20 times

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Tin exposed to dry oxygen (104–106 L) at 100°C has been studied by ESCA. The ESCA shift for the tin 3d5/2 line was 1.65 eV and the separation between this line and the oxygen 1s line was 43.90 eV. The oxide was identified by comparing its ESCA spectra with those of SnO and SnO2 samples carefully prepared in vacuum. Clean SnO samples were prepared in vacuum by decomposing SnO2 crystallites at high temperature and depositing the vapor product on a gold substrate. The resulting films were identified to be red SnO by ion back‐scattering and by Mössbauer experiments. Clean SnO2 samples were prepared by diamond‐filing bulk SnO2 crystals in vacuum. Both of these oxides were found to have the same separation between the oxygen 1s and the tin oxide 3d5/2 lines and hence, the same chemical shift. For this reason, the oxidized tin was identified by comparing its valence band and O/Sn ratio, rather than its chemical shift, with those of the SnO and SnO2 samples. The oxidized tin was found to consist of both SnO and SnO2.
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81.05.Bx Metals, semimetals, and alloys
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Abstract: Auger analysis of superconducting ’’NbN’’ reactively sputtered films

I. L. Singer, S. A. Wolf, W. H. Lowrey, and J. S. Murday

J. Vac. Sci. Technol. 15, 625 (1978); http://dx.doi.org/10.1116/1.569643 (1 page)

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74.78.-w Superconducting films and low-dimensional structures
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
74.25.Sv Critical currents
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition

LEED–Auger study of the (11̄0) surface of a 1% Si–Fe single crystal

P. E. Viljoen, J. P. Roux, and E. G. Boonstra

J. Vac. Sci. Technol. 15, 626 (1978); http://dx.doi.org/10.1116/1.569644 (5 pages)

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An optimal procedure involving ion bombardment at elevated temperatures for surface cleaning is described. The observed LEED pattern basically consists of the ideal (11̄0) surface of a bcc structure together with extra spots indicating additional periodicity in the 〈001〉 direction. A possible explanation is proposed. Intensity profiles for different beams and their temperature dependence are discussed. An effective surface Debye temperature of 300 K and a predicted bulk value of about 420 K are deduced. Annealing at temperatures above 780° C leads to diffusion of sulfur atoms from the bulk and to ordering on the surface. The resulting LEED pattern is described in terms of a rationally related lattice with a unit net [(16/3)1/2× (8/3)1/2] with respect to the basic (11̄0) ‐surface p lattice of a bcc crystal.
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81.05.Bx Metals, semimetals, and alloys
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Surface structure and orbital symmetries of (110) surface states of GaAs

D. J. Chadi

J. Vac. Sci. Technol. 15, 631 (1978); http://dx.doi.org/10.1116/1.569645 (6 pages) | Cited 3 times

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The orbital symmetries of (110) surface electronic states of GaAs for three different surface‐relaxation models are analyzed using the tight‐binding method. Although the atomic displacements involved in all three relaxations are basically very similar, they give rise to different orderings of some surface states when these states are characterized by their orbital symmetries. Angle‐resolved photoemission measurements using polarized radiation therefore provide a useful tool for distinguishing between competing surface structures determined from low‐energy electron‐diffraction studies. A comparison of the recent, preliminary measurements by Williams and Lapeyre with our theoretical results shows that only the ’’bond‐relaxation’’ model for the surface is in agreement with the experimental results. Local densities of surface states and the orbital symmetries of surface states are discussed.
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73.20.-r Electron states at surfaces and interfaces
71.20.-b Electron density of states and band structure of crystalline solids

Abstract: Conversion electron Mössbauer studies of amorphous Fe–Si thin films

R. S. Oswald, M. Ron, and M. Ohring

J. Vac. Sci. Technol. 15, 637 (1978); http://dx.doi.org/10.1116/1.569646 (1 page)

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64.70.K- Solid-solid transitions
76.80.+y Mössbauer effect; other γ-ray spectroscopy
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
68.55.-a Thin film structure and morphology

ir study of molecules adsorbed on metal surfaces by surface electromagnetic wave spectroscopy

Y. J. Chabal and A. J. Sievers

J. Vac. Sci. Technol. 15, 638 (1978); http://dx.doi.org/10.1116/1.569647 (4 pages) | Cited 2 times

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The infrared spectra of monolayer coverages of two different molecules (KReO4 and SF6) physisorbed on metal surfaces have been measured in the 10‐μm region by means of a new surface electromagnetic wave (SEW) coupling technique in conjunction with a CO2 laser. Coverages as low as two monolayers can be readily monitored in agreement with predictions based on an optical sum rule. The new coupling configuration is based on the principle of inhomogeneous wave coupling and allows the matching of both the propagation wave vector and the spatial profile of the SEW. Our method is both more efficient and more convenient for SEW spectroscopy than the conventional prism technique.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
78.66.-w Optical properties of specific thin films
78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
78.30.-j Infrared and Raman spectra

Some effects of anisotropic vibrations in LEED

M. Úlehla and H. L. Davis

J. Vac. Sci. Technol. 15, 642 (1978); http://dx.doi.org/10.1116/1.569648 (5 pages)

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A formalism is presented which enables effects of certain types of vibrational anisotropy to be included in LEED calculations. Results from a demonstration calculation are presented and compared with a similar calculation where no anisotropy was present.
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61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
61.05.jd Theories of electron diffraction and scattering
63.20.K- Phonon interactions

Abstract: Study of semiconductor surfaces using an atom‐probe field ion microscope (1) Hydrogen chemisorption on silicon

Toshio Sakurai, T. T. Tsong, and R. J. Culbertson

J. Vac. Sci. Technol. 15, 647 (1978); http://dx.doi.org/10.1116/1.569649 (3 pages) | Cited 1 time

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Semiconductors, particularly silicon, are some of the most important materials in technology today. Surface properties of Si have been intensively investigated by many techniques, such as low‐energy electron diffraction (LEED)1,2 and ultraviolet photoemission spectroscopy (UPS).3,4 Most recently Sakurai and Hagstrum have studied surface electronic structures for hydrogen chemisorption on various silicon surfaces using ion neutralization spectroscopy (INS) and UPS.5 Their study suggested the formation of new hydride surface phases, such as SiH5b and SiH3,5c in addition to a well known monohydride phase SiH.5a However this conclusion was drawn without observation of those surface molecules. Here we present a new approach to the study of hydrogen chemisorption on Si surfaces. We applied atom‐probe field ion microscopy to observe directly these surface compounds. We have also succeeded in achieving a new atomic resolution of silicon in field ion microscopy.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Abstract: Surface structure analysis of Pt(111) and Pt(100) surfaces by MeV ion backscattering and channeling (SAIBAC)

P. R. Norton, J. A. Davies, D. P. Jackson, N. Matsunami, and J. U. Andersen

J. Vac. Sci. Technol. 15, 650 (1978); http://dx.doi.org/10.1116/1.569650 (1 page)

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68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
68.37.-d Microscopy of surfaces, interfaces, and thin films

Abstract: Atomic model and valence‐band features in the MVV Auger spectra of copper

H. H. Madden, D. M. Zehner, and J. R. Noonan

J. Vac. Sci. Technol. 15, 650 (1978); http://dx.doi.org/10.1116/1.569651 (2 pages)

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79.20.Fv Electron impact: Auger emission
32.80.Hd Auger effect (including Coster-Krönig transitions)
71.20.-b Electron density of states and band structure of crystalline solids

Abstract: Chemical state effects in Auger electron spectroscopy

T. E. Madey, P. H. Holloway, R. R. Rye, and J. E. Houston

J. Vac. Sci. Technol. 15, 651 (1978); http://dx.doi.org/10.1116/1.569652 (1 page)

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79.20.Fv Electron impact: Auger emission
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
32.80.Hd Auger effect (including Coster-Krönig transitions)
31.70.Dk Environmental and solvent effects

Abstract: One‐electron theory of Auger lineshapes: Silicon L23VV and L1L23V

Dwight R. Jennison

J. Vac. Sci. Technol. 15, 652 (1978); http://dx.doi.org/10.1116/1.569653 (1 page)

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32.80.Hd Auger effect (including Coster-Krönig transitions)
31.70.Dk Environmental and solvent effects
71.70.-d Level splitting and interactions

Abstract: Solid state and atomic features in the valence‐band Auger spectra of copper, silver, and gold

C. J. Powell

J. Vac. Sci. Technol. 15, 652 (1978); http://dx.doi.org/10.1116/1.569654 (1 page)

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32.80.Hd Auger effect (including Coster-Krönig transitions)
71.20.-b Electron density of states and band structure of crystalline solids

Abstract: Monte Carlo modeling of phase changes in the chemisorption system O/W(110)

W. Y. Ching, D. L. Huber, M. Fishkis, and M. G. Lagally

J. Vac. Sci. Technol. 15, 653 (1978); http://dx.doi.org/10.1116/1.569655 (2 pages) | Cited 2 times

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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)

Abstract: Chemisorption site determination by angle‐resolved ultraviolet photoemission spectroscopy

C. H. Li and S. Y. Yong

J. Vac. Sci. Technol. 15, 655 (1978); http://dx.doi.org/10.1116/1.569656 (1 page)

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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
79.60.Jv Interfaces; heterostructures; nanostructures

Abstract: Extended fine structure above the vanadium 2s appearance potential edge

W. T. Elam, P. I. Cohen, T. L. Einstein, Y. Fukuda, and Robert L. Park

J. Vac. Sci. Technol. 15, 655 (1978); http://dx.doi.org/10.1116/1.569657 (1 page)

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32.80.Hd Auger effect (including Coster-Krönig transitions)
79.20.Fv Electron impact: Auger emission
31.70.Dk Environmental and solvent effects

Abstract: Laminar Cu2O growth on (111) Cu single‐crystal surfaces

J. H. Ho and R. W. Vook

J. Vac. Sci. Technol. 15, 656 (1978); http://dx.doi.org/10.1116/1.569658 (1 page)

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68.55.-a Thin film structure and morphology
81.05.Bx Metals, semimetals, and alloys
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Abstract: Formation of cyanates in the interaction of nitric oxide, carbon monoxide, and hydrogen over platinum, rhodium, ruthenium, and osmium

R. J. H. Voorhoeve and L. E. Trimble

J. Vac. Sci. Technol. 15, 656 (1978); http://dx.doi.org/10.1116/1.569659 (1 page)

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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
82.20.Pm Rate constants, reaction cross sections, and activation energies

Abstract: CO/H2 surface complex on W(100)

J. Benziger and R. J. Madix

J. Vac. Sci. Technol. 15, 657 (1978); http://dx.doi.org/10.1116/1.569660 (1 page)

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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Abstract: Nitrogen, oxygen, and carbon monoxide chemisorption on polycrystalline titanium surfaces

Y. Fukuda, W. T. Elam, and R. L. Park

J. Vac. Sci. Technol. 15, 657 (1978); http://dx.doi.org/10.1116/1.569661 (1 page)

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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
73.30.+y Surface double layers, Schottky barriers, and work functions
79.20.Hx Electron impact: secondary emission

Abstract: An unusual surface complex of copper on polystyrene

J. M. Burkstrand

J. Vac. Sci. Technol. 15, 658 (1978); http://dx.doi.org/10.1116/1.569662 (1 page) | Cited 1 time

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68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
79.60.Jv Interfaces; heterostructures; nanostructures
68.55.-a Thin film structure and morphology

Abstract: Auger quantitative analysis on some metal oxides

H. L. Yeh, H. F. Tighe, and D. L. Hunt

J. Vac. Sci. Technol. 15, 658 (1978); http://dx.doi.org/10.1116/1.569663 (1 page)

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82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Abstract: Angle‐resolved photoemission and LEED measurements using a Vidicon intensity processor: Chlorine on Si(111)

S. P. Weeks and J. E. Rowe

J. Vac. Sci. Technol. 15, 659 (1978); http://dx.doi.org/10.1116/1.569664 (1 page)

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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
79.60.Jv Interfaces; heterostructures; nanostructures
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Abstract: First intercontinental test of vacuum transfer device

J. P. Hobson

J. Vac. Sci. Technol. 15, 659 (1978); http://dx.doi.org/10.1116/1.569665 (1 page)

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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
68.90.+g Other topics in structure, and nonelectronic properties of surfaces and interfaces; thin films and low-dimensional structures (restricted to new topics in section 68)

Abstract: Experimental studies using light ions to simulate fusion neutron damage effects on mechanical properties

D. L. Styris and R. H. Jones

J. Vac. Sci. Technol. 15, 661 (1978); http://dx.doi.org/10.1116/1.569666 (3 pages)

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61.80.Hg Neutron radiation effects
61.80.Jh Ion radiation effects
28.41.Bm Fuel elements, preparation, reloading, and reprocessing

Enhanced etching of ion‐implanted silicon nitride in buffered hydrofluoric acid

Peter D. Parry and Suzanne P. Bristol

J. Vac. Sci. Technol. 15, 664 (1978); http://dx.doi.org/10.1116/1.569667 (4 pages) | Cited 3 times

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The preferential etching of ion‐implanted pyrolytic silicon nitride (Si3N4) and plasma‐deposited silicon nitride in buffered hydrofluoric acid has been studied as a function of ion mass, energy, and dose. The dose dependence of etching enhancement produced by light ions (H and He) shows that the relevant concentration parameter is the density of displaced atoms rather than the concentration of the implanted impurity. In addition to the atomic displacement mechanism, a species‐dependent contribution is seen. For Si3N4 the enhancement produced by most ions is 7, whereas P gives 15. For plasma‐deposited nitride, the average enhancement is 3, with values of 8 observed for P and 1.5 for B. These enhancement values can be reduced by in situ annealing due to localized ion beam heating. This annealing occurs at bulk sample temperatures which are several hundred degrees Centrigrade lower than the temperatures required to produce the same result in a furnace anneal.
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61.80.Jh Ion radiation effects
81.65.-b Surface treatments

Effect of primary ion energy and surface chemistry on the secondary ion yields in low‐energy SIMS experiments

Ming L. Yu

J. Vac. Sci. Technol. 15, 668 (1978); http://dx.doi.org/10.1116/1.569668 (4 pages)

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The chemisorption of oxygen on W(100) and Mo(100) single‐crystal surfaces was studied using a static mode SIMS technique at primary ion energies ranging from 150 eV to 2 keV. The following secondary ion yields O−, WO−2, and MoO−2 were found to be sensitive to the changes in the chemisorbed oxygen layer at different stages of chemisorption. Significant enhancement in the sensitivity of the O− yield to the chemisorption process was observed when the energy of the Ne+ primary ion energy was below 500 eV.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Some performance tests of a microarea AES

G. Todd and H. Poppa

J. Vac. Sci. Technol. 15, 672 (1978); http://dx.doi.org/10.1116/1.569669 (3 pages) | Cited 14 times

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A UHV microarea Auger analysis system that has submicron Auger analysis capability is described. Capabilities of this versatile surface research system include secondary electron imaging, microarea Auger analysis in both EdN/dE and EN (E) modes, macroarea AES, sputter ion cleaning, and a multiple specimen handling facility. A thermal field emission Zr/W(100) source is used for microarea AES. A spatial resolution of 1000 Å in the secondary electron image is demonstrated. Auger line scans in both EdN/dE and EN (E) modes show submicron edge resolution under nonideal specimen conditions.
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82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Surface blistering of molybdenum irradiated with 75–350‐keV helium ions

C. R. Fahlstrom and M. K. Sinha

J. Vac. Sci. Technol. 15, 675 (1978); http://dx.doi.org/10.1116/1.569670 (4 pages) | Cited 3 times

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Polycrystalline molybedenum samples have been irradiated at room temperature with helium ions of energy from 75 to 350 keV in high vacuum. Irradiation parameters such as ion energy, total dose, and dose rate were varied and surfaces were examined in a scanning electron microscope. The average blister diameter increases with increasing ion energy and the blister number density increases with increasing total dose of helium. The critical dose for blister formation is independent of the beam flux in the range of 6.7×1013 to 2×1015 ions cm−2 s−1. However, the average blister diameter changes with the change of flux. When the molybdenum surface is successively bombarded with varying ion energies, both the diameter and the number density of the blisters is significantly reduced as compared to monoenergetic helium bombardment.
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61.80.Jh Ion radiation effects
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Application of a double‐pass CMA to ion scattering from some actinide materials

W. P. Ellis and T. N. Taylor

J. Vac. Sci. Technol. 15, 679 (1978); http://dx.doi.org/10.1116/1.569671 (5 pages) | Cited 3 times

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Surfaces of polycrystalline U, Th, and single‐crystalline UO2(111) have been examined with He+, Ne+, and Ar+ at incident beam energies Ei?650 eV. For this study we used a double‐pass cylindrical mirror analyzer in a custom vacuum system intended primarily for UPS chemisorption studies. The incident ion beam was perpendicular to the axis of the analyzer. Our approach was to determine if the instrument could serve in a complementary ISS capacity and, if so, what the ion scattering conditions are for detecting both surface oxygen and the actinides. Data are presented illustrating definitive results. But severe limitations in resolution are evident, the energies do not correspond exactly to a simple binary‐collision model, and with He+ the scattering intensities from actinide materials are quite low by comparison with a Au reference.
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68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
82.80.-d Chemical analysis and related physical methods of analysis

Energy distributions of sputtered copper neutrals and ions

Theodore R. Lundquist

J. Vac. Sci. Technol. 15, 684 (1978); http://dx.doi.org/10.1116/1.569672 (4 pages) | Cited 11 times

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Direct quantitative analysis of surfaces by secondary ion mass spectrometry (SIMS) will depend on an understanding of the yield ratio of ions to neutrals. This ratio as a function of the energy of the sputteredd particles has been obtained for a clean polycrystalline copper surface sputtered by 1000–3000 eV Ar+. The energy distributions of both neutral and ionized copper were measured with a retarding potential analyzer (RPA) using potential modulation differentiation and signal averaging. The maximum for both distributions is identical and occurs near 2.5 eV. The energy distributions of neutrals is more sharply peaked than that of the ions, presumably as a consequence of more efficient neutralization of slow escaping ions by the mobile electrons of copper. The ion–neutral ratio, which is found to be proportional to En/2 with 0.6<n<1.4, is compared with various ionization models.
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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
07.75.+h Mass spectrometers

Study of radiation damage in metals by positron annihilation

W. B. Gauster

J. Vac. Sci. Technol. 15, 688 (1978); http://dx.doi.org/10.1116/1.569673 (9 pages) | Cited 1 time

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Positron annihilation is a sensitive technique for probing defects in metals and it has recently been shown to be a valuable tool for the study of radiation damage. After an introduction to the three basic experimental methods (angular correlation, Doppler broadening, and lifetime measurements), the interaction of positrons with lattice defects is reviewed. Results for the annealing of damage after low‐temperature irradiation are used to show that positron annihilation has provided new information on annealing kinetics. The role of positron techniques in characterizing complex defect structures resulting from high‐temperature neutron irradiation is reviewed and the possible utility of positron annihilation as a nondestructive monitor of property changes is pointed out.
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61.80.Hg Neutron radiation effects
78.70.Bj Positron annihilation
61.72.-y Defects and impurities in crystals; microstructure
81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties

Optical and electrical properties of ion‐beam‐textured Kapton and Teflon

Michael J. Mirtich and James S. Sovey

J. Vac. Sci. Technol. 15, 697 (1978); http://dx.doi.org/10.1116/1.569674 (5 pages) | Cited 2 times

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An electron bombardment argon ion source was used to ion etch polyimide (Kapton) and fluorinated ethylene propylene, FEP (Teflon). Samples of polyimide and FEP were exposed to 0.5–1.0‐keV Ar ions at ion current densities of 1.0–1.8 mA/cm2 for various exposure times. Changes in the optical and electrical properties of the samples were used to characterize the exposure. Spectral reflectance and transmitance measurements were made between 0.33 and 2.6 μm using an integrating sphere after each exposure. From these measurements, values of solar absorptance were obtained. Total emittance measurements were also recorded for some samples. Surface resitivity was used to determine changes in the electrical conductivity of the etched samples. A scanning electron microscope was used to record surface structure after exposure. Presented in the paper are spectral optical data, resistivity measurements, calculated absorptance and emittance measurements, along with photomicrographs of the surface for the various exposures to Ar ions.
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61.80.Jh Ion radiation effects
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.65.-b Surface treatments
72.80.Le Polymers; organic compounds (including organic semiconductors)
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Combined low‐energy ion scattering and x‐ray photoelectron spectroscopy study of Ta2O5 bombarded by 500–3000‐eV He ions

G. C. Nelson

J. Vac. Sci. Technol. 15, 702 (1978); http://dx.doi.org/10.1116/1.569675 (4 pages) | Cited 2 times

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The low‐energy ion backscattering spectra of Ta2O5 obtained with He as the probe gas exhibit a pronounced low‐energy tail on the metal peak and a strong incident ion energy dependence of the oxygen to tantalum peak intensity ratio. To determine the effect differential scattering cross sections, ion neutralization, and sample reduction have on these spectral features, a combined ISS–XPS study has been carried out. The data indicate that the sample is not reduced by the He ion beam and that a resonant‐type neutralization plays a dominant role both in tailing and in the variation of the oxygen to tantalum peak intensity ratio.
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82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Trapping of deuterium implanted into stainless steel at low temperatures

C. J. Altstetter, R. Behrisch, and B. M. U. Scherzer

J. Vac. Sci. Technol. 15, 706 (1978); http://dx.doi.org/10.1116/1.569493 (4 pages) | Cited 3 times

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Stainless steel 316 specimens have been implanted with deuterium ions at 7 keV up to doses of 2×1018 D/cm2 at −120°C. Trapped quantities and depth profiles of the implanted atoms have been determined using the 3He (d,p) 4He nuclear reaction, using both the product particles for making the analyses. Up to doses of 5×1017 D/cm2 the implanted deuterons were retained within the analyzing zone, but at higher fluences the amounts retained no longer increased linearly with the bombardment dose. Deuterium to metal atom ratios of nearly 1:1 were observed. The density of retained deuterium was not a function of holding time at −120°C, but upon warming, the loss of deterium could be measured. At roughly −50°C the rate of loss was a maximum, and by +40°C only a few percent of the original amount of deuterium remained.
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61.80.Jh Ion radiation effects
52.55.Pi Fusion products effects (e.g., alpha-particles, etc.), fast particle effects
28.52.-s Fusion reactors

Surface damage of molybdenum and TZM alloy under D+ impact

S. K. Das, M. Kaminsky, and P. Dusza

J. Vac. Sci. Technol. 15, 710 (1978); http://dx.doi.org/10.1116/1.569494 (4 pages)

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The surface damage of polycrystalline molybdenum and TZM alloy under 40‐, 60‐, and 120‐keV D+ impact has been investigated for irradition in both pulsed and continuous modes for total doses varying from 1.7×1017 to 2.2×1019 ions/cm2 and for target temperature varying from ambient temperature to 400° C. Analysis by scanning electron microscopy of the Mo samples held at ambient temperatures during D+ irradiations in both pulsed and continuous modes revealed surface damage due to blistering for the 40‐ and 60‐keV irradiations for doses ranging from 8.7×1017 to 8.1×1018 ions/cm2, but no detectable damage for the 120‐keV D+ irradiations for doses ranging from 4.3×1018 to 2.2×1019 ion/cm2. This observed difference in the blistering behavior is attributed to the difference in the ambient target temperature for the 120‐keV irradiation and both the 40‐ and 60‐keV irradiations. For irradiations at temperatures above 300° C, no blisters could be detected for any of the three energies. For similar irradiation conditions, TZM alloy showed a reduction in blistering as compared to molybdenum.
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61.80.Jh Ion radiation effects
28.52.-s Fusion reactors

Determination of quantitative sputter rates of iron oxide by Auger electron spectroscopy (AES) and ellipsometry

Robert G. Hart and Gary W. Simmons

J. Vac. Sci. Technol. 15, 714 (1978); http://dx.doi.org/10.1116/1.569495 (4 pages) | Cited 1 time

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AES was used to study the sputtering rates for thermally grown iron oxide films bombarded with 1–5‐keV Ar+. Ellipsometric measurements of the films were used to determine the film thickness and to confirm composition. Calibration was made for sputtering rates as a function of ion flux and ion energy. Special attention was placed upon the effects of specimen−ion source and specimen−electron energy analyzer alignment in establishing this calibration. This work is relevant to experiments in which ion etching is used as a means of obtaining depth profiles of oxidized iron and ferrous alloys.
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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Mechanical properties on ion‐beam‐textured surgical implant alloys

A. J. Weigand

J. Vac. Sci. Technol. 15, 718 (1978); http://dx.doi.org/10.1116/1.569496 (7 pages) | Cited 3 times

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An electron‐bombardment Hg ion thruster was used as an ion source to texture surfaces of materials used to make orthopedic and/or dental prostheses or implants. The materials textured include 316 stainless steel, titanium–6% aluminum, 4% vanadium, and cobalt–20% chromium, 15% tungsten. To determine the effect of ion texturing on the ultimate strength and yield strength, stainless steel and Co–Cr–W alloy samples were tensile tested to failure. Three types of samples of both materials were tested. One type was ion textured (the process also heats each sample to 300°C), another type was simply heated to 300°C in an oven, and the third type was untreated. Stress–strain diagrams, 0.2%‐offset yield strength data, total elongation data, and area reduction data will be presented. Fatigue specimens of ion‐textured and untextured 316 stainless steel and Ti–6% Al–4% V were tested. Included as an ion‐textured sample is a Ti–6% Al–4% V sample which was ion machined by means of a Ni screen sputter mask so as to produce an array of 140×140×60‐μm‐deep pits. A table is presented that compares the fatigue characteristics of ion‐textured and untextured samples. Scanning electron microscopy was used to characterize the ion‐textured surfaces. An electron‐beam microprobe was used to analyze the cross sections of the ion‐textured samples.
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87.85.E- Neural prosthetics
87.85.F- Smart prosthetics
61.80.Jh Ion radiation effects
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization

Abstract: Ultrahigh depth resolution in characterization of surfaces: practical application

G. R. Sparrow

J. Vac. Sci. Technol. 15, 725 (1978); http://dx.doi.org/10.1116/1.569497 (1 page)

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82.80.-d Chemical analysis and related physical methods of analysis
68.90.+g Other topics in structure, and nonelectronic properties of surfaces and interfaces; thin films and low-dimensional structures (restricted to new topics in section 68)

Abstract: Composition changes in GaAs due to low‐energy ion bombardment

I. L. Singer, J. S. Murday, and L. R. Cooper

J. Vac. Sci. Technol. 15, 725 (1978); http://dx.doi.org/10.1116/1.569498 (1 page) | Cited 1 time

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61.80.Jh Ion radiation effects
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

TFTR vacuum system

Bruce D. Abel

J. Vac. Sci. Technol. 15, 726 (1978); http://dx.doi.org/10.1116/1.569499 (8 pages)

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The Tokamak Fusion Test Reactor (TFTR) will be the first magnetic plasma device in the United States capable of producing energy in any significant quantity by the fusion of deuterium and tritium nuclei. The function of the vacuum pumping system is to provide the high‐vacuum environment for plasma initiation, to remove spent plasma constituents at the conclusion of each plasma pulse, and to provide initial high vacuum and regeneration of the neutral beam cryopanels. Radiation produced by the fusion reaction and the requirement to pump tritium have presented significant design problems not ordinarily encountered in the design of ultrahigh vacuum systems. The configuration and piping schematic of the preliminary design vacuum pumping system capable of fulfilling the requirements is discussed. The selection process for the high‐vacuum pumps is reviewed and the rationale for the use of turbomolecular pumps, based on projected overall vacuum pumping system reliability, is presented. A computer was used to predict vacuum system performance. Preliminary computer‐generated pumpdown curves are presented for plasma pulsing operations and pumpdowns from atmospheric pressure.
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52.55.Fa Tokamaks, spherical tokamaks
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices
52.55.Pi Fusion products effects (e.g., alpha-particles, etc.), fast particle effects
07.30.-t Vacuum apparatus
28.52.-s Fusion reactors

Turbomolecular pump vacuum system for the Princeton Large Torus

H. Frederick Dylla

J. Vac. Sci. Technol. 15, 734 (1978); http://dx.doi.org/10.1116/1.569500 (7 pages)

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A turbomolecular pump vacuum system has been designed and installed on the Princeton Large Torus (PLT). Four vertical shaft, oil‐bearing, 1500‐l/s turbomolecular pumps have been interfaced to the 6400‐l PLT vacuum vessel to provide a net pumping speed of 3000 l/s for H2. The particular requirements and problems of tokamak vacuum systems are enumerated. A vacuum control system is described which protects the vacuum vessel from contamination and protects the turbomolecular pumps from damage under a variety of possible failure modes. The performance of the vacuum system is presented in terms of pumping speed mesurements and residual gas behavior.
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07.30.Hd Vacuum testing methods; leak detectors
52.55.Fa Tokamaks, spherical tokamaks
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices

Cryosorption pumping of deuterium by MS‐5A at temperatures above 4.2 K for fusion reactor applications

P. W. Fisher and J. S. Watson

J. Vac. Sci. Technol. 15, 741 (1978); http://dx.doi.org/10.1116/1.569501 (4 pages)

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An excalibur CVR‐1106 cryosorption pump was fitted with a special cooling system to permit measurement of deuterium pumping speeds at temperatures between 6 and 20 K. Pumping speeds were found to be a function of feed rate, loading prior to each run, loading during runs, and thermal treatment between runs. At feed rates <3×10−4 Torr l s−1 cm−2, speeds were near 1 l s−1 cm−2 initially and declined monotonically with loading. At high feed rates, speeds reached a higher maximum (∠3 l s−1 cm−2) but also generally declined with loading; however, after 50–100 Torr l had accumulated, the pump underwent a spontaneous transition which effected a return to the original (high) pumping speed. This transition was accompanied by pressure spikes in the test chamber and temperature spikes in the sieve panel. Initial speeds for each consecutive run equaled the final speed for the preceding run if the pump was maintained at operating temperature; however, if it was warmed to 77 K and recooled, a restoration to the maximum speed was observed at the beginning of the next run.
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28.52.-s Fusion reactors
07.30.Cy Vacuum pumps

Abstract: Vacuum and surface properties of the Alcator tokamak

E. Apgar

J. Vac. Sci. Technol. 15, 745 (1978); http://dx.doi.org/10.1116/1.569502 (1 page)

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07.30.-t Vacuum apparatus
52.55.Fa Tokamaks, spherical tokamaks
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices

Behavior of sorb–ac wafer pumps in plasma machines

L. Rosai, B. Ferrario, and P. della Porta

J. Vac. Sci. Technol. 15, 746 (1978); http://dx.doi.org/10.1116/1.569503 (5 pages) | Cited 1 time

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Vacuum pumps used in machines studying plasma physics are exposed to peculiar operating conditions. Especially the auxiliary pumps, such as cryopumps and getter pumps which are used in close proximity to the discharge or in injectors, can be exposed to very severe conditions. These pumps must exhibit very high pumping speeds and capacities, particularly for hydrogen, and must operate over a wide range of pressures. They must also be safe and reliable in use. Finally, their characteristics should not be influenced by energetic particle bombardment, radiation incidence, sputtered material on the sorbing surface, and by the presence of radioactive substances. The behavior of getter pumps based on the use of nonevaporable getter material and on a modular structure, known as sorb–ac wafer pumps, is reviewed and discussed here. The operating conditions and the behavior under radiation, particle bombardment, vacuum breakage accidents, etc. of these pumps meet most of the requirements in nuclear fusion machines and make them particularly suitable for this field of application.
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28.52.-s Fusion reactors
52.55.Pi Fusion products effects (e.g., alpha-particles, etc.), fast particle effects
07.30.Bx Degasification, residual gas
52.75.-d Plasma devices

Advances in cleaning metal and glass surfaces to micron‐level cleanliness

Irving F. Stowers

J. Vac. Sci. Technol. 15, 751 (1978); http://dx.doi.org/10.1116/1.569504 (4 pages) | Cited 3 times

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A high‐pressure 6.9‐MPa liquid spraying technique has been developed to remove small (≳5 μm) contaminant particles from large (100 m2) surface areas. Chemically polished and etched 304 stainless‐steel components are solvent sprayed to achieve cleanliness levels of less than 10 particle/cm2≳5 μm diameter. The high‐pressure and high‐liquid‐velocity cleaning technique can remove 99.9% of ≳5‐μm‐diam particles in 5–10 s compared to only 20–60%≳5‐μm particles by ultrasonic cleaning in 2–10 min. High levels of particulate cleanliness are required for large solid–state laser systems where contaminants may migrate to optical surfaces and cause severe pitting. The pitted glass must be removed and periodically repolished to maintain acceptable beam quality. Special Class 100 clean room procedures and equipment have been developed to determine the degree of cleanliness of laser components and to maintain cleanliness during installation and operation. Development of these cleaning procedures resulted in greatly reduced failure rates for solid‐state disk amplifiers. Although developed specifically for cleaning optical components, the basic technique should find wide application in any field requiring particulate‐free surfaces.
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81.05.Bx Metals, semimetals, and alloys
81.05.Kf Glasses (including metallic glasses)
81.65.-b Surface treatments
42.15.Eq Optical system design
42.87.-d Optical testing techniques
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

The nitrogen pressure in a vacuum system

D. Edwards

J. Vac. Sci. Technol. 15, 755 (1978); http://dx.doi.org/10.1116/1.569505 (3 pages)

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Since the N2 outgassing rate from walls of a vacuum system is generally recognized to be very small, the presence of an N2 pressure in the system is a useful indication of the presence of real leaks to the atmosphere. A technique of thermal desorption mass spectrometry is introduced which allows the N2 pressure in the background gas of a baked system to be separated from a CH4 background to a minimum level of N2 detectability of ∠1% of the CO background pressure. In typical baked systems (of which an example is given), it is possible to determine the sum of all real N2 leaks from atmosphere at a level of ∠10−11 Torr l/s. This feature makes the technique ideally suited to large complex systems since the leak rate can be evaluated before detailed leak‐finding procedures are initiated.
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07.30.Hd Vacuum testing methods; leak detectors
07.30.Bx Degasification, residual gas

Glow discharge processing versus bakeout for aluminum storage ring vacuum chambers

N. R. Dean, E. W. Hoyt, M. T. Palrang, and B. G. Walker

J. Vac. Sci. Technol. 15, 758 (1978); http://dx.doi.org/10.1116/1.569506 (3 pages)

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Experiments were carried out on laboratory and prototype scale systems in order to establish the feasibility of argon discharge processing the PEP storage ring aluminum vacuum chambers. Electron‐induced desorption rates showed significant reductions following bakeout and/or argon glow discharge treatment (≳1019 ions cm−1). Data are presented and discussed in relation to advantages and problems associated with: water removal, argon trapping and subsequent release, electron energy dependence, discharge distribution, and surface plasma chemical effects.
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29.20.db Storage rings and colliders
07.30.-t Vacuum apparatus
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Simple vacuum gauge using TaN thin films in the pressure range of 105 to 10−3 Pa

T. Shioyama, T. Takiguchi, and S. Ogawa

J. Vac. Sci. Technol. 15, 761 (1978); http://dx.doi.org/10.1116/1.569507 (3 pages) | Cited 3 times

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Experiments investigating the use of TaN thin films for measurements of pressure over a wide range have proved to give good results, because the TaN thin films have large effective heat conducting areas available to increase the sensitivity, suitable resistance, and large temperatures coefficients of resistance. These experiments led to the construction of a film system consisting of a TaN thin film deposited on a miniature 7059 Corning glass substrate by reactive plasma sputtering. With this system, it is possible to measure pressure changes in the range of 105 to 10−3 Pa. A detailed description of the characteristics of the TaN film gauge as well as the calibration curves are given.
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07.30.Dz Vacuum gauges

Abstract: An integrated approach to vacuum systems engineering

G. J. Still

J. Vac. Sci. Technol. 15, 764 (1978); http://dx.doi.org/10.1116/1.569508 (1 page)

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Abstract Unavailable
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07.30.-t Vacuum apparatus

Performance of a cryopump–ion pump system

J. E. de Rijke

J. Vac. Sci. Technol. 15, 765 (1978); http://dx.doi.org/10.1116/1.569509 (3 pages)

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In a cryopump, hydrogen is pumped through cryosorption using solid sorbents. At temperatures at which the pump operates, the vapor pressure of hydrogen exceeds the pressure that has to be obtained. The cryopump therefore, has a limited capacity for hydrogen. The capacity, and the pumping speed, will be dependent on the pressure at which the system operates and on the comtamination of the sorbent. The speed of a cryopump for hydrogen has been measured as a function of pressure in the range between 10−4 and 10−8 Torr(10−3–10−6 Pa). Also the speeds for nitrogen and argon have been measured. Gauge constants for the various gases were used to obtain ’’true’’ pressures for each gas type. To determine the dependence of system performance on sorbent contamination, the speed for hydrogen has been measured as a function of the number of times the system has been cycled from atmosphere. To augment the performance of the cryopump–ion pumps have been used. Speed performance as a function of system pressure and as a function of the number of times the system has been cycled, is compared to the use of a cryopump alone.
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07.30.Cy Vacuum pumps
07.30.Bx Degasification, residual gas

Problems with turbomolecular pumps in magnetic fields

W. Becker and J. Henning

J. Vac. Sci. Technol. 15, 768 (1978); http://dx.doi.org/10.1116/1.569510 (3 pages) | Cited 3 times

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With the increase of the application of turbomolecular pumps in plasma physics the problem of strong magnetic fields in the vicinity of the turbomolecular pumps comes up more and more frequently. If the rotor of a turbomolecular pump turns with high speed in a magnetic field eddy currents in the rotor will cause undesirable heating of the pump. The maximal magnetic flux density specific for each turbomolecular pump is determined by experiment for a series of pumps. For higher densities of the magnetic field shielding elements must be applied, because excessive heating of the pump rotor would cause destruction of the pump.
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07.30.Cy Vacuum pumps

Precision molecular flow measurement and control for single and multigas systems

Robert A. Kiesling, John J. Sullivan, and Donald J. Santeler

J. Vac. Sci. Technol. 15, 771 (1978); http://dx.doi.org/10.1116/1.569511 (4 pages) | Cited 1 time

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This paper presents recent advances in precision molecular flow measurement and control for single backfill gases as well as describing the important factors to be considered in multigas flow and ratio control of several gases at pressures above 0.0133 Pa. A comprehensive theoretical analysis is given describing the variables to be considered in practical systems. Theoretical and experimental data are presented on a new design of molecular flow element specifically designed for vacuum flow applications of any gas, including corrosive types. Single and multigas measurement and control applications using the new flow element with electronic manometer measurement and control instrumentation include reactive sputtering, reactive ion etching, and plasma reactor deposition and etching systems.
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47.80.-v Instrumentation and measurement methods in fluid dynamics
47.45.Dt Free molecular flows
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Properties and use of perfluoro polyethers for vacuum applications

G. Caporiccio and R. A. Steenrod

J. Vac. Sci. Technol. 15, 775 (1978); http://dx.doi.org/10.1116/1.569512 (4 pages) | Cited 2 times

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Perfluoro polyether are fully fluorinated fluids. They are chemically inert and excellent lubricants. For vacuum use they have the added advantage that solid films are rarely deposited when the vapors are subject to electron and ion bombardment. The development of various vacuum fluids is discussed, together with physical properties such as mass range, boiling range, viscosity, vapor pressure, and chromatography measurements. Performances of the specially developed fluids in vacuum pumps are presented together with field experiences in a variety of applications.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Differentially pumped six‐inch metal sealed gate valve

D. J. Harra

J. Vac. Sci. Technol. 15, 779 (1978); http://dx.doi.org/10.1116/1.569513 (4 pages)

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Vacuum valves rely on an ability to make and remake intimate contact between their seal and seat materials over their entire main seal perimeters. In many applications, valves must be operable in the presence of small amounts of particulate matter. In such applications, a common failure mode for both metal and elastomer sealed valves results from the inadvertent incorporation of foreign particles into the main seal area during their operation. The use of a back‐up seal with differential pumping of the intermediate space is a well‐known technique for reducing the effect of small leaks. A modification to allow differential pumping of the main seal of a six‐inch metal sealed valve described previously is discussed. Experimental results obtained with a modified valve are presented.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Abstract: Analytical methods recently used with molecular‐beam epitaxy (MBE) technique

P. Bouchaib, A. Grillo, and M. M. Noblet

J. Vac. Sci. Technol. 15, 783 (1978); http://dx.doi.org/10.1116/1.569514 (1 page)

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68.55.-a Thin film structure and morphology
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
82.80.-d Chemical analysis and related physical methods of analysis

Abstract: Diffstaks with integral cold traps

B. D. Power

J. Vac. Sci. Technol. 15, 783 (1978); http://dx.doi.org/10.1116/1.569515 (1 page)

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Abstract Unavailable
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07.30.Hd Vacuum testing methods; leak detectors
07.30.Cy Vacuum pumps

Abstract: Sliding‐vane rotary vacuum pumps with selected accessories as a basic pump for vacuum processing

K. Fischer and J. Henning

J. Vac. Sci. Technol. 15, 783 (1978); http://dx.doi.org/10.1116/1.569699 (1 page)

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07.30.Cy Vacuum pumps
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Abstract: WGK‐C pumps: Gas‐cooled roots pumps—chemical series

J. Henning and H. Lang

J. Vac. Sci. Technol. 15, 784 (1978); http://dx.doi.org/10.1116/1.569700 (1 page)

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Abstract Unavailable
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07.30.Cy Vacuum pumps

Abstract: Mechanical boosters incorporating self‐limiting power transmission

H. Wycliffe

J. Vac. Sci. Technol. 15, 784 (1978); http://dx.doi.org/10.1116/1.569701 (1 page)

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Abstract Unavailable
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
07.30.Bx Degasification, residual gas

Abstract: New series of vapor‐handling vacuum pumps

Max Baron

J. Vac. Sci. Technol. 15, 785 (1978); http://dx.doi.org/10.1116/1.569702 (1 page)

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07.30.Cy Vacuum pumps

Abstract: New modular surface analysis system

G. R. Conner and P. F. McGinnis

J. Vac. Sci. Technol. 15, 785 (1978); http://dx.doi.org/10.1116/1.569703 (1 page)

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Abstract Unavailable
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73.20.-r Electron states at surfaces and interfaces
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Abstract: Unique instrument for multiple technique surface characterization by ESCA, scanning Auger, UPS, and SIMS

P. W. Palmberg and W. M. Riggs

J. Vac. Sci. Technol. 15, 786 (1978); http://dx.doi.org/10.1116/1.569704 (1 page)

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Abstract Unavailable
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73.20.-r Electron states at surfaces and interfaces
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Abstract: New instrumental capabilities in Auger electron microscopy

W. R. Bottoms, N. J. Taylor, and J. A. Schoeffel

J. Vac. Sci. Technol. 15, 786 (1978); http://dx.doi.org/10.1116/1.569705 (1 page)

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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
73.20.-r Electron states at surfaces and interfaces

Abstract: Quadrupole gas analyzer with integral microprocessor

D. H. Holkeboer, W. Parfitt, F. H. Schlereth, and P. F. McGinnis

J. Vac. Sci. Technol. 15, 787 (1978); http://dx.doi.org/10.1116/1.569706 (1 page)

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Abstract Unavailable
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82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
07.75.+h Mass spectrometers

Abstract: Ion beam thinning penetration switch

G. Smith

J. Vac. Sci. Technol. 15, 787 (1978); http://dx.doi.org/10.1116/1.569707 (1 page) | Cited 2 times

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Abstract Unavailable
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Abstract: New different development in high‐vacuum feedthroughs

H. von Zweck

J. Vac. Sci. Technol. 15, 788 (1978); http://dx.doi.org/10.1116/1.569708 (1 page)

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Abstract Unavailable
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Abstract: New high reliability stainless‐steel valve and valve trap for use in production applications

W. E. Graves

J. Vac. Sci. Technol. 15, 788 (1978); http://dx.doi.org/10.1116/1.569709 (1 page)

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Abstract Unavailable
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Abstract: Production system for ion milling with a large‐diameter ion beam

L. D. Bollinger

J. Vac. Sci. Technol. 15, 789 (1978); http://dx.doi.org/10.1116/1.569710 (1 page)

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41.75.Ak Positive-ion beams
41.75.Cn Negative-ion beams
29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative
81.65.-b Surface treatments

Abstract: Novel spin test for adherence, wear resistance, and thermal shock of thin films

Richard P. Riegart

J. Vac. Sci. Technol. 15, 789 (1978); http://dx.doi.org/10.1116/1.569711 (1 page)

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46.55.+d Tribology and mechanical contacts
46.80.+j Measurement methods and techniques in continuum mechanics of solids
68.60.-p Physical properties of thin films, nonelectronic
81.70.-q Methods of materials testing and analysis

Abstract: ’’DID’’ tester for measuring the presence of ultra‐adherence in thin films

Richard P. Riegart

J. Vac. Sci. Technol. 15, 790 (1978); http://dx.doi.org/10.1116/1.569712 (1 page)

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46.55.+d Tribology and mechanical contacts
46.80.+j Measurement methods and techniques in continuum mechanics of solids
68.60.-p Physical properties of thin films, nonelectronic

Abstract: Tridimensional characterization of solid surfaces by SIMS analysis

A. Diebold, A. C. Grillo, and M. M. Noblet

J. Vac. Sci. Technol. 15, 790 (1978); http://dx.doi.org/10.1116/1.569713 (1 page)

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82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
07.75.+h Mass spectrometers
68.90.+g Other topics in structure, and nonelectronic properties of surfaces and interfaces; thin films and low-dimensional structures (restricted to new topics in section 68)

Auger study of surface carbon and oxygen on thorium following ion bombardment

R. Bastasz and C. Colmenares

J. Vac. Sci. Technol. 15, 791 (1978); http://dx.doi.org/10.1116/1.569714 (3 pages)

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The composition of a thorium metal surface has been monitored using Auger electron spectroscopy following Ar+ bombardment at different temperatures. After extended Ar+, bombardment, enough contaminated overlayers were removed to expose a surface region containing only thorium, bulk impurities, and imbedded argon. The main impurities, carbon and oxygen, differed in their behavior when the sample was annealed following bombardment. The amount of surface carbon either increased or remained constant during annealing depending upon the temperature of the sample during bombardment. The amount of surface oxygen decreased rapidly when the sample was heated above 500°C regardless of the sample temperature during bombardment. These experiments indicate that preparation of clean, annealed thorium surfaces requires ion bombardment at temperatures ?400°C.
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81.05.Bx Metals, semimetals, and alloys
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
68.90.+g Other topics in structure, and nonelectronic properties of surfaces and interfaces; thin films and low-dimensional structures (restricted to new topics in section 68)

Thermal noise in balances and its significance for physical measurements

J. A. Poulis and F. N. Hooge

J. Vac. Sci. Technol. 15, 795 (1978); http://dx.doi.org/10.1116/1.569715 (5 pages) | Cited 2 times

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The fundamental limits to the accuracy of automated balances are discussed in connection with application of those balances. The applications concerned are manometers, magnetic susceptibility measurements, measurements of the De Haas–Einstein effect, and measurements of gravitational constant. In the last three applications the fundamental thermal noise accompanying the use of the balance is shown to be the limiting factor.
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07.50.-e Electrical and electronic instruments and components
07.55.-w Magnetic instruments and components
06.20.Jr Determination of fundamental constants
05.40.-a Fluctuation phenomena, random processes, noise, and Brownian motion

An automated Faraday balance susceptometer

J. D. Kulick and J. C. Scott

J. Vac. Sci. Technol. 15, 800 (1978); http://dx.doi.org/10.1116/1.569716 (5 pages)

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A computer‐controlled Faraday balance has been constructed, calibrated, and tested. Magnetic moment and susceptibility measurements can be performed at fields 0–15.5 kG, and at temperatures 2–300 K. Gradient coils in the magnet gap permit separate variation of the field and its inhomogeneity. The system is interfaced to a computer which collects data from the electrobalance and thermometer, and controls the magnitude of the applied field and the sign of the field gradient. An independent programmer controls the temperature in such a way that computer‐monitored sweeps of temperature are achieved with optimal thermal equilibration.
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07.55.-w Magnetic instruments and components
75.20.-g Diamagnetism, paramagnetism, and superparamagnetism
75.30.Cr Saturation moments and magnetic susceptibilities
33.15.Kr Electric and magnetic moments (and derivatives), polarizability, and magnetic susceptibility

Errors due to zero uncertainties and buoyancy in the gravimetric measurements of sorption isotherms

Erich Robens and Th. Gast

J. Vac. Sci. Technol. 15, 805 (1978); http://dx.doi.org/10.1116/1.569717 (5 pages)

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Besides the influences of Knudsen forces and convection which are due to thermal gas flow, a zero shift during cooling down of the sample in vacuo may seriously affect the measurement of adsorption isotherms at low temperatures. This applies especially to the measurement of nitrogen isotherms at 77 K for surface area and pore size determination. Microporous samples present difficulties in determining the necessary buoyancy corrections for the sample itself; in addition, the buoyancy of the adsorbed layers has to be taken into account.
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06.30.Dr Mass and density
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Force measurement in chemical analysis

B. Schubart, J. A. Poulis, and Th. Gast

J. Vac. Sci. Technol. 15, 810 (1978); http://dx.doi.org/10.1116/1.569718 (3 pages)

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In the cooperation between the Technological University of Eindhoven, the Technical University of Berlin, and the Application Laboratory of Sartorius Werke Göttingen, research has been performed on the application of ponderomatic measurements for the detection of fluids in liquid chromatography and other fields of chemical analysis. For this research a special balance has been developed, which in future might be used under vacuum conditions. The apparatus has been described at the Salford VMT conference last year; in the present paper we present experimental results. For the comparison of these results with those of other measurements we shall have to go into some detail about the choice of the frequency of the electric voltage used.
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82.80.-d Chemical analysis and related physical methods of analysis
77.22.Ch Permittivity (dielectric function)

Simultaneous measurement of weight and torque in controlled atmospheres by magnetic suspension

Th. Gast and K. Koppe

J. Vac. Sci. Technol. 15, 813 (1978); http://dx.doi.org/10.1116/1.569719 (4 pages) | Cited 3 times

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Experiments exist where a vertical force, for instance the weight of a sample, and a torque caused by a certain physical effect, have to be measured simultaneously. Examples are the determination of molecular weight according to Knudsen or the simultaneous measurement of permittivity and dielectric loss of very small samples. Such measurement may be carried out with the aid of free magnetic suspension in the following way: A horseshoe magnet with poles turned upward is suspended beneath a second one, whose poles point downward. The distance between the mutually attracting poles is kept constant by automatic control. The lower magnet carries two vanes of copper sheet, aligned in a horizontal plane, which are in the sensitivity range of four symmetrically arranged inductive sensors, fixed to the upper magnet. The sensors are connected in a Wheatstone bridge in such a manner, that the distance and angular position of the vanes can be measured simultaneously. The signal for the distance is compared with a reference signal and the deviation causes a controlling current through a winding on the upper magnet. In equilibrium, this current is a measure of weight or other vertical forces acting on a sample, which is attached to the lower magnet. Because of the quasielastic behavior of the magnetic lines of forces, the signal for angular deflection is a measure of torque. Preliminary results are shown.
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07.55.-w Magnetic instruments and components
06.30.-k Measurements common to several branches of physics and astronomy
85.70.-w Magnetic devices

Abstract: Limitations to the sensitivity of measurements in vacuum of force and weight

J. A. Poulis and F. N. Hooge

J. Vac. Sci. Technol. 15, 817 (1978); http://dx.doi.org/10.1116/1.569720 (1 page)

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Abstract Unavailable
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06.30.-k Measurements common to several branches of physics and astronomy

Mass artifacts using a Cahn‐RG microbalance in water vapor

R. Vasofsky and A. W. Czanderna

J. Vac. Sci. Technol. 15, 818 (1978); http://dx.doi.org/10.1116/1.569721 (3 pages)

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Corrections for a ’’mass gain’’ artifact by the weighing mechanism have been found necessary when exposing a Cahn‐RG‐UHV microbalance in water vapor up to 1.3×103‐Pa water vapor. The effect varies linearly with load from 0.2 to 0.9 g and amounts to an apparent mass gain of 27 μg per 100 mg of load at 1.3×103 Pa and 22° C. About two hours were required to reach equilibrium after exposure to water vapor at pressures between 1.3 and 2.4×103 Pa. Similar equilibration times are required in comparable pressure decrements, except that times ranging to as high as 33 h are necessary during final evacuation. Thus, the artifact depends on time, pressure, and load. The mass defect is tentatively ascribed to sorption by the polymer used for insulating the torque motor. Recoating the windings in the torque motor, which was done by the Cahn Division of Ventron, reduced the effect to 12.2 μg at a 100‐mg load and 1.3×103 Pa, but the time, pressure, and load dependence of the artifact remained.
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06.30.Dr Mass and density
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
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