Browse - Journal of Vacuum Science & Technology Archives 1964-1982

Select this Article

Chemical information from Auger electron spectroscopy

H. H. Madden

J. Vac. Sci. Technol. 18, 677 (1981); http://dx.doi.org/10.1116/1.570927 (13 pages) | Cited 34 times

Show Abstract

The nature of chemical information in Auger electron spectroscopy (AES) data is reviewed with special emphasis on data from solid surface systems. Two strategies are most frequently used to extract this information: (i) measuring and analyzing energy (chemical) shifts in Auger peaks; and (ii) making use of the shapes of Auger signals to determine the chemical environment at the site of the initial core hole. Chemical shift data are primarily illustrated by highlighting the interaction of oxygen with solids; and analyses of these data based on core‐level binding‐energy shifts, relaxation, and hole–hole interactions are outlined and discussed. Auger transitions that involve valence electrons are usually those for which lineshapes are taken as indications of the local chemistry at the initial core‐hole site. Attempts at extracting valence band density‐of‐states information from lineshapes are proving successful and this approach to the surface chemical information in AES is illustrated with the aid of examples dealing with the interaction of silicon with hydrogen and with oxygen. The use of the AES lineshapes simply as ’’fingerprints’’ of the core‐hole‐site chemistry is examined and illustrated by examples which include studies of silicon nitride properties, of solid surface properties related to catalytic reactions, and of passive films on iron. Auger decay activated desorption processes are briefly examined and found to promise new and unique chemical information when combined with conventional AES. Some gas phase AES studies are also briefly reviewed.

+

Show PACS

82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
79.20.Fv	Electron impact: Auger emission
81.65.-b	Surface treatments
82.65.+r	Surface and interface chemistry; heterogeneous catalysis at surfaces

Select this Article

Quantitative analysis of iron oxides using Auger electron spectroscopy combined with ion sputtering

D. F. Mitchell, G. I. Sproule, and M. J. Graham

J. Vac. Sci. Technol. 18, 690 (1981); http://dx.doi.org/10.1116/1.570928 (5 pages) | Cited 8 times

Full Text: | Download PDF

+

Show Abstract

Quantitative analysis of α‐Fe₂O₃, Fe₃O₄ and FeO films to an accuracy of ±0.3 at.% is achievable using derivative‐mode Auger electron spectroscopy. This requires the use of a sensitivity factor obtained from iron oxide standards. During ion sputtering, the best measure of iron concentration is found to be the magnitude of the negative excursion of the Auger signal rather than the usual peak to peak value. For all the iron oxides sputtered in both argon and xenon (voltage range 1–4 keV) there is a 4.7±0.2 at.% reduction in oxygen content except for 1 keV xenon, where the value is 3.7±0.2 at.%. The rate at which sputter equilibrium is established depends on the ion species, the voltage, and the sample topography. A sputter mixing depth of ∠8 to 60 Å is indicated.

+

Show PACS

82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
81.65.-b	Surface treatments
81.70.-q	Methods of materials testing and analysis

Select this Article

Thickness periodicity in the Auger line shapes from epitaxial (111) Pd/ (111) Cu films

S. S. Chao, R. W. Vook, and Y. Namba

J. Vac. Sci. Technol. 18, 695 (1981); http://dx.doi.org/10.1116/1.570929 (5 pages) | Cited 1 time

Full Text: | Download PDF

+

Show Abstract

Epitaxial Pd films were formed on (111) Cu substrate films at room temperature under UHV conditions. The growth of these Pd films was monitored in situ by Auger electron spectroscopy (AES) and studied subsequently by transmission electron microscopy (TEM). It was found that Pd grows on Cu by a layer mechanism. A measure of the line shapes of the 61 eV MMM Cu and 329 eV MVV Pd derivative Auger line doublets was defined and called the R‐factor. For the Pd overgrowth and Cu substrate, the R‐factor was observed to fluctuate with increasing Pd film thickness. The average period of these fluctuations was found to be approximately one monoatomic layer. These fluctuations are interpreted as arising from the superposition of Auger electrons originating in the flat and edge regions of the bilayer film, the relative numbers of which vary cyclically as the Pd film thickens.

+

Show PACS

82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
68.55.-a	Thin film structure and morphology

Select this Article

Chemical effects in ion scattering spectroscopy

R. C. McCune

J. Vac. Sci. Technol. 18, 700 (1981); http://dx.doi.org/10.1116/1.570930 (9 pages) | Cited 6 times

Full Text: | Download PDF

+

Show Abstract

The principal use of low‐energy ion scattering spectroscopy (ISS) as a surface analytical tool has been the identification of surface layer atoms through binary collision kinematics. In this mode of analysis, the chemical state of the atom is usually not discernible with the data normally obtained. This paper reviews a number of observations which indicate that chemical state information or the nature of local atom arrangements may be inferred from certain aspects of the experimental data. The earliest recognition of chemical state information resulted from study of resonant charge exchange processes for particular ion/atom combinations. By appropriate manipulation of experimental data, it is possible to obtain fingerprint spectra in the inverse velocity domain for various compounds. Recently, two techniques used in this laboratory have been applied to the study of surface atom configurations. In the first, the energy dependence of scatter peak height ratios in ionic compounds is used to infer an atom shielding susceptibility for various cations in oxide matrices. Secondly, a number of peak shift and doublet scattering peaks have been observed in special cases where the surface layer decomposes under bombardment by the probe ion beam.

+

Show PACS

68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics
79.20.Rf	Atomic, molecular, and ion beam impact and interactions with surfaces
82.80.-d	Chemical analysis and related physical methods of analysis

Select this Article

Summary Abstract: Auger spectroscopy of metal carbonyls and nitrosyls

R. R. Rye and G. D. Stucky

J. Vac. Sci. Technol. 18, 709 (1981); http://dx.doi.org/10.1116/1.570931 (2 pages)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

33.50.Hv	Radiationless transitions, quenching
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Select this Article

Summary Abstract: ISS chemical effects in elemental and compound semiconductors

W. L. Baun

J. Vac. Sci. Technol. 18, 711 (1981); http://dx.doi.org/10.1116/1.570932 (2 pages)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics
79.20.Rf	Atomic, molecular, and ion beam impact and interactions with surfaces
82.80.-d	Chemical analysis and related physical methods of analysis

Select this Article

Summary Abstract: Auger lineshape analysis of polymers: polyethylene and poly(ethylene oxide)

J. A. Kelber, R. R. Rye, and G. C. Nelson

J. Vac. Sci. Technol. 18, 712 (1981); http://dx.doi.org/10.1116/1.570933 (2 pages)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

36.20.Kd	Electronic structure and spectra
33.70.Jg	Line and band widths, shapes, and shifts
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Select this Article

Chemical information from XPS—applications to the analysis of electrode surfaces

N. S. McIntyre, S. Sunder, D. W. Shoesmith, and F. W. Stanchell

J. Vac. Sci. Technol. 18, 714 (1981); http://dx.doi.org/10.1116/1.570934 (8 pages) | Cited 40 times

Full Text: | Download PDF

+

Show Abstract

Some of the difficulties in using x‐ray photoelectron spectroscopy (XPS) for the chemical characterization of surfaces are considered. XPS chemical shifts are often quite small, compared to spectral line widths and to the accuracy of the reference data. Moreover, subtle differences in peak shape are often degraded by inadequate counting statistics. However, progress toward better chemical characterization is being made by using rigorous peak‐fitting routines and correlating chemical shift information from several photoelectron and Auger electron lines. This paper describes two examples of these procedures in the study of electrode processes: (1) the use of multiple line shifts to follow the evolution and growth of different copper oxide phases during anodic polarization of a copper–metal electrode; (2) the use of peak‐fitting routines to determine stoichiometric changes on a UO₂ electrode surface with good precision.

+

Show PACS

33.60.+q	Photoelectron spectra
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
81.05.Bx	Metals, semimetals, and alloys
81.05.Je	Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.65.-b	Surface treatments

Select this Article

Chemistry of corrosion layers on amorphous FeNiCrPB alloys

D. R. Baer and M. T. Thomas

J. Vac. Sci. Technol. 18, 722 (1981); http://dx.doi.org/10.1116/1.570935 (5 pages) | Cited 6 times

Full Text: | Download PDF

+

Show Abstract

X‐ray photoelectron spectroscopy was used to examine the composition and chemical state of anodically‐formed corrosion layers on FeNiCrPB amorphous alloys in a 1/2 M Na₂SO₄ solution with pH 5. Amorphous alloys are highly resistant to corrosion and particular attention was given to the chemical states of Cr and P, the elements known to play a major role in the corrosion resistance. A careful sample transfer procedure was established to minimize changes in the sample during transfer from solution to vacuum. A systematic and reproducible progression of chemical states was observed that was related to structure in the polarization curve and to elemental stability diagrams. The largest change in the P 2p oxidation state occurred between 0 and 700 mV_SCE while the Cr2p_3/2 oxidation state changed between 700 and 1150 mV_SCE. Surface concentrations of P and Fe increased with increasing anodic potential, while concentrations of Ni, Cr, and B decreased.

+

Show PACS

82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
81.05.Bx	Metals, semimetals, and alloys

Select this Article

Correction for loss effects in valence‐band XPS spectra by deconvolution

G. D. Davis and M. G. Lagally

J. Vac. Sci. Technol. 18, 727 (1981); http://dx.doi.org/10.1116/1.570936 (5 pages) | Cited 2 times

Full Text: | Download PDF

+

Show Abstract

We present XPS valence band spectra for GaAs (110) and GeSe (001) that have been corrected for coherent loss effects by deconvolution of an instrument/loss function that includes a source function for an unmonochromatized source, a backscattered‐electron spectrum to account for energy losses, and an analyzer function. The results are compared with background‐subtracted spectra. The deconvolution yields spectra that have significantly greater intensity deep in the band, bringing measurements into closer agreement with theory than is achieved with background subtraction.

+

Show PACS

73.20.-r	Electron states at surfaces and interfaces
71.20.-b	Electron density of states and band structure of crystalline solids
81.65.-b	Surface treatments
79.90.+b	Other topics in electron and ion emission by liquids and solids and impact phenomena (restricted to new topics in section 79)

Select this Article

Application of ESCA to corrosion studies of glasses containing simulated nuclear wastes

L. R. Pederson, M. T. Thomas, and G. L. McVay

J. Vac. Sci. Technol. 18, 732 (1981); http://dx.doi.org/10.1116/1.570937 (5 pages)

Full Text: | Download PDF

+

Show Abstract

ESCA, in combination with ion sputtering, was used to obtain compositional depth profiles of complex glasses which had been leached in DI water. The earliest and most obvious feature of aqueous attack was alkali depletion from the near surface regions of the glasses. Further corrosion was slowed by a surface buildup of various elements, which included aluminum, iron, nickel, titanium, zirconium, cerium, and neodymium. Elemental releases were calculated from the ESCA results, which were corrected for variations in the sputter rate through the reaction layer, and were compared to those measured directly by ICP solution analysis. The degree of agreement between the two methods was used to assess the importance of matrix dissolution in addition to selective component leaching in the aqueous corrosion of the glasses.

+

Show PACS

81.05.Kf	Glasses (including metallic glasses)
81.65.-b	Surface treatments
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Select this Article

Molecular secondary ion mass spectrometry (SIMS)

R. J. Colton

J. Vac. Sci. Technol. 18, 737 (1981); http://dx.doi.org/10.1116/1.570938 (11 pages) | Cited 7 times

Full Text: | Download PDF

+

Show Abstract

Ion beams have been used for a number of years in material analysis. SIMS has been used recently to study the interaction of adsorbed gases on metal surfaces and the molecular structure of organic, inorganic, biologic, and polymeric compounds. This paper reviews the advancing field of molecular SIMS applied in two distinct areas: as an analytical tool for surface analysis and as a sensitive ionization source for nonvolatile and thermally‐labile molecules. The present understanding of the molecular ion formation process is illustrated by results of calculation and experiment. Comparison of SIMS with other new ionization methodologies in mass spectrometry such as field, plasma, and laser desorption shows clear spectral similarities. In addition, SIMS demonstrates an extreme surface sensitivity, best detection limits in the picogram range, and high mass capability (≳5000 amu). Ionization of nonvolatile and thermally labile molecules can occur via three separate processes involving cationization/anionization, electron transfer, or direct sputter emission of positive and negative secondary ions. Over 80 papers are referenced.

+

Show PACS

79.20.Rf	Atomic, molecular, and ion beam impact and interactions with surfaces
07.75.+h	Mass spectrometers
82.80.Ms	Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Select this Article

Summary Abstract: Auger induced desorption of covalent and ionic systems

D. E. Ramaker, C. T. White, and J. S. Murday

J. Vac. Sci. Technol. 18, 748 (1981); http://dx.doi.org/10.1116/1.570939 (2 pages) | Cited 14 times

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

68.03.Fg	Evaporation and condensation of liquids
68.43.Mn	Adsorption kinetics
79.20.Fv	Electron impact: Auger emission
71.15.-m	Methods of electronic structure calculations

Select this Article

Summary Abstract: Lithium compound identification in thermally activated batteries by ISS and SIMS

G. C. Nelson, P. A. Neiswander, and J. Q. Searcy

J. Vac. Sci. Technol. 18, 750 (1981); http://dx.doi.org/10.1116/1.570940 (2 pages)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

82.47.Aa	Lithium-ion batteries
82.47.Cb	Lead-acid, nickel-metal hydride and other batteries
84.60.-h	Direct energy conversion and storage
82.80.Ms	Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
82.47.-a	Applied electrochemistry
82.30.Hk	Chemical exchanges (substitution, atom transfer, abstraction, disproportionation, and group exchange)

Select this Article

Low pressure CVD of III–V compounds

J. P. Duchemin

J. Vac. Sci. Technol. 18, 753 (1981); http://dx.doi.org/10.1116/1.570941 (3 pages) | Cited 5 times

Full Text: | Download PDF

+

Show Abstract

In this paper it is shown that the low pressure organometallic chemical vapor deposition (LP‐MOCVD) technique of growing semiconductors is generally applicable to most of the III–V compounds that are currently of interest. The principles of the technique are described and then specific applications are detailed. It has been found that the LP‐MOCVD technique offers the following advantages: reduction of autodoping, virtual elimination of parasitic reactions, and the possibility of growth on large areas of semiconductor substrates.

+

Show PACS

81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a	Thin film structure and morphology
85.30.-z	Semiconductor devices
73.30.+y	Surface double layers, Schottky barriers, and work functions

Select this Article

Morphological defects arising during MBE growth of GaAs

R. Z. Bachrach and B. S. Krusor

J. Vac. Sci. Technol. 18, 756 (1981); http://dx.doi.org/10.1116/1.570942 (9 pages) | Cited 7 times

Full Text: | Download PDF

+

Show Abstract

The growth by molecular beam epitaxy of GaAs and GaAlAs is reviewed, with special attention given to morphological defects which can occur. Although the allowed stoichiometric growth regime for this system is quite wide, more restricted conditions are required when overall perfection is important. The paper characterizes the growth process within the framework of achieving material suitable for GaAs–GaAlAs double heterostructure lasers. This includes substrate preparation, growth initiation, and growth evolution. Specific morphological defects which are found to be observed quite generally are characterized and some explanations will be ventured. Achieving featureless growths is important for integrated optic devices and this is possible over large area substrates.

+

Show PACS

68.55.-a	Thin film structure and morphology
81.15.-z	Methods of deposition of films and coatings; film growth and epitaxy

Select this Article

Effects of Ga and Si ionization on the growth of Ga doped Si MBE

S. Shimizu and S. Komiya

J. Vac. Sci. Technol. 18, 765 (1981); http://dx.doi.org/10.1116/1.570943 (4 pages) | Cited 6 times

Full Text: | Download PDF

+

Show Abstract

Gallium doped Si films were epitaxially grown on Si(100) substrates using a partially ionized Ga molecular beam at various substrate temperatures ranging from 300 to 1000 K with incident Si and Ga beam fluxes of 5×10¹⁴ atoms s⁻¹ cm⁻², which corresponds to 0.1 nm/s assuming the sticking coefficient to be unity. The surface structure and the surface composition were observed by an in situ RHEED–AES system. Ga ionization produced no observable change in surface structure or surface composition as compared with Ga doping without ionization. However, an increase of the carrier concentration was observed by Ga doping with a partially ionized molecular beam under the following ionization condition: an ion energy of 180 eV with 5% Ga ionization. Moveover, the lowering of the epitaxial temperature was observed using a partially ionized Si molecular beam under the ionization conditions: an ion energy ranging from 30 to 180 eV with ≲7% Si ionization.

+

Show PACS

68.55.-a	Thin film structure and morphology
68.60.-p	Physical properties of thin films, nonelectronic
61.05.jh	Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
61.72.U-	Doping and impurity implantation

Select this Article

Summary Abstract: Silicon MBE

J. C. Bean

J. Vac. Sci. Technol. 18, 769 (1981); http://dx.doi.org/10.1116/1.570944 (3 pages) | Cited 2 times

Full Text: | Download PDF

+

Show Abstract

This paper summarizes a review of recent developments in silicon molecular beam epitaxy. These include ionized doping, heteroepitaxial growth on insulators and silicides, and MBE devices.

+

Show PACS

81.15.-z	Methods of deposition of films and coatings; film growth and epitaxy
81.10.Aj	Theory and models of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation
68.55.-a	Thin film structure and morphology
72.20.-i	Conductivity phenomena in semiconductors and insulators

Select this Article

Novel device structures by molecular beam epitaxy

C. E. C. Wood

J. Vac. Sci. Technol. 18, 772 (1981); http://dx.doi.org/10.1116/1.570945 (6 pages) | Cited 1 time

Full Text: | Download PDF

+

Show Abstract

This paper briefly reviews a few selected technologically important areas where Molecular Beam Epitaxy has been used to advantage. These include the use of MBE to study and improve ohmic and Schottky metallizations to GaAs and the invention of new types of variable barrier height diodes. The proven potential of MBE grown ternary alloy structures as materials for enhanced microwave and high speed digital devices and the use of selected area epitaxy for state of the art digital integrated circuit elements are also discussed.

+

Show PACS

68.55.-a	Thin film structure and morphology
72.80.Ey	III-V and II-VI semiconductors
73.40.Ei	Rectification
73.61.At	Metal and metallic alloys

Select this Article

Core threshold photoemission spectroscopy from the As 3d core level of GaAs (110) and effects of Ge chemisorption

P. Zurcher, G. J. Lapeyre, R. Avci, and J. Anderson

J. Vac. Sci. Technol. 18, 778 (1981); http://dx.doi.org/10.1116/1.570946 (6 pages) | Cited 1 time

Full Text: | Download PDF

+

Show Abstract

We have investigated the excitation of the As 3d core level of clean and Ge covered GaAs (110) surfaces into low lying conduction band states by observing core‐hole decay emission. The investigation was carried out by using synchrotron radiation to record photoemission spectra in the CIS and EDC modes. In contrast to the Ga 3d core excitation, the As 3d core excitation was found to be nonexcitonic in character. The CIS shows three structures at hυ = 43.0, 46.1, and 49.5 eV, which were strongly influenced by Ge‐chemisorption. With about a monolayer of Ge, the structures are reduced to a considerably larger degree than the photoemission structure associated with the Ga 3d exciton. The As 3d core level is excited into surface related p‐like states lying 2.6, 5.7, and 9.1 eV above the valence band maximum, ’’followed’’ by the radiationless Auger decay of the core holes. The inferred conduction band states are compared to recent band calculations and the state at 2.6 eV is assigned to the Ga‐dangling‐bond surface state. With the assumption that the As 3d core excitation is to the same surface state as the Ga 3d core excitation, we estimate the exciton binding energy for the latter excitations to be ∠1.8 eV.

+

Show PACS

81.65.-b	Surface treatments
73.20.-r	Electron states at surfaces and interfaces
73.40.Lq	Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
79.60.Jv	Interfaces; heterostructures; nanostructures

Select this Article

Photoemission studies of heterojunction interface formation: Ge–GaAs(110) and Ge–Si(111)

G. Margaritondo, N. G. Stoffel, A. D. Katnani, H. S. Edelman, and C. M. Bertoni

J. Vac. Sci. Technol. 18, 784 (1981); http://dx.doi.org/10.1116/1.570947 (3 pages) | Cited 4 times

Full Text: | Download PDF

+

Show Abstract

A comparison between the formation mechanisms of Ge–GaAs(110) and Ge–Si(111) interfaces is presented. The localized valence band states and core‐level states were detected by photoemission spectroscopy with synchrotron radiation. Evidence was found that both kinds of interfaces are sharp and that Ge forms smooth overlayers at room temperature. The shifts in energy of the localized electronic states saturates at a much earlier stage of the interface formation for Ge–GaAs than for Ge–Si. The measured band discontinuities sharply disagree with the predictions of ’’linear’’ interface models. More sophisticated interface models give band discontinuities in excellent agreement with our experimental results for Ge–GaAs—while no satisfactory theoretical explanation is currently available for our Ge–Si results.

+

Show PACS

73.40.Lq	Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
79.60.-i	Photoemission and photoelectron spectra

Select this Article

Reactive interdiffusion at metal–CdS and metal–CdSe interfaces

C. F. Brucker and L. J. Brillson

J. Vac. Sci. Technol. 18, 787 (1981); http://dx.doi.org/10.1116/1.570948 (5 pages) | Cited 6 times

Full Text: | Download PDF

+

Show Abstract

The initial stages of room temperature interface formation for reactive and unreactive metals on II–VI single crystal semiconductors have been studied using UPS, XPS, AES, Kelvin work function, and photoinduced band bending measurements. For reactive metals we see evidence for extended reacted interface formation with new chemical structure and electronic properties. For example, Cu on CdS or CdSe forms a thick (∠250 Å) reacted layer as shown by the appearance of dissociated Cd and Cu–chalcogen alloy formation. Pre‐evaporation of a thin (10 Å) Ti interlayer dramatically modulates many aspects of subsequent interdiffusion, including junction abruptness and stability, stoichiometry of semiconductor out‐diffusion, and the nature of intermetallic compounds that are formed. In contrast, In (unreactive) shows no evidence for chemical reaction although substantial in‐diffusion is indicated. These microscopic parameters of interface formation are related to macroscopic Schottky barrier formation.

+

Show PACS

73.30.+y	Surface double layers, Schottky barriers, and work functions
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

Select this Article

LEED intensity analysis of the structure of Al on GaAs(110)

A. Kahn, D. Kanani, J. Carelli, J. L. Yeh, C. B. Duke, R. J. Meyer, A. Paton, and L. Brillson

J. Vac. Sci. Technol. 18, 792 (1981); http://dx.doi.org/10.1116/1.570949 (5 pages)

Full Text: | Download PDF

+

Show Abstract

The atomic structure of 1/2 monolayer of Al on GaAs(110) is examined by low energy electron diffraction (LEED) intensity analysis. Room temperature deposition produces a disordered overlayer that does not modify the substrate structure. However, an ordered 1×1 structure results when the system is annealed at 450°C. The AES and LEED measurements suggest a reaction of Al on GaAs to form AlAs, in agreement with some of the photoemission data. As a preliminary result, the multiple scattering analysis indicates that a structure for which Al replaces the second layer Ga provides the most satisfactory description of the measured LEED intensities.

+

Show PACS

61.05.jh	Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
61.66.Fn	Inorganic compounds

Select this Article

Surface phases of GaAs(100) and AlAs(100)

R. Z. Bachrach, R. S. Bauer, P. Chiaradia, and G. V. Hansson

J. Vac. Sci. Technol. 18, 797 (1981); http://dx.doi.org/10.1116/1.570950 (5 pages) | Cited 22 times

Full Text: | Download PDF

+

Show Abstract

The surface phases of GaAs(100) and AlAs(100) have been investigated with angle integrated photoemission. Detailed information about the surface reconstructions as function of Ga/As ratio has been obtained from changes in the surface core level intensities as a function of reconstruction. Large changes are also shown to occur in the surface valence band density of states and surface core level binding energy shifts as a function of reconstruction. We find that whereas the GaAs(100) surface shows ordered reconstructions over a wide composition range, the AlAs(100) surface is predominately disordered and only a 3×2 reconstruction was found in a narrow composition range.

+

Show PACS

73.20.Hb	Impurity and defect levels; energy states of adsorbed species
73.40.-c	Electronic transport in interface structures

Select this Article

Summary Abstract: Low‐energy electron diffraction study of the surface‐defect structure of Ge grown epitaxially on GaAs(110)

H. M. Clearfield, D. G. Welkie, and M. G. Lagally

J. Vac. Sci. Technol. 18, 802 (1981); http://dx.doi.org/10.1116/1.570951 (2 pages) | Cited 1 time

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

68.55.-a	Thin film structure and morphology
68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics
61.05.J-	Electron diffraction and scattering
61.05.jh	Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)

Select this Article

Material and device research for VLSI in Japan

T. Sugano

J. Vac. Sci. Technol. 18, 804 (1981); http://dx.doi.org/10.1116/1.570952 (6 pages) | Cited 3 times

Full Text: | Download PDF

+

Show Abstract

Some of the recent achievements in research of materials and devices toward very large scale integration (VLSI) are reviewed, with emphasis on the growth technology of silicon crystals, electron beam lithography, trap states at a Si–SiO₂ interface, plasma technologies and devices. The Czochralski method with magnetic field, plasma anodization technique, and the triode plasma etching system are interesting methods.

+

Show PACS

85.40.-e	Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
85.40.Bh	Computer-aided design of microcircuits; layout and modeling
85.30.De	Semiconductor-device characterization, design, and modeling
85.30.Tv	Field effect devices

Select this Article

Microstructure of beam‐annealed silicon

J. M. Gibson

J. Vac. Sci. Technol. 18, 810 (1981); http://dx.doi.org/10.1116/1.570953 (8 pages)

Full Text: | Download PDF

+

Show Abstract

Ion implantation damage in semiconductors can be removed by irradiation with particle beams. Short, energetic photon, ion or electron pulses seem to achieve this effect by inducing a first‐order phase change in the near‐surface region. The microstructure of pulsed‐laser and ion‐beam irradiated Si has been studied with transmission electron microscopy, taking advantage of high‐resolution and microdiffraction techniques. Laser‐irradiated samples, thinned in cross section at pulse‐energies near the threshold for epitaxial regrowth, neatly display some features of the nucleation and regrowth phenomena, which are consistent with thermal melting. Some solid‐state growth can be seen beneath the presumably melted region. Direct evidence that the melting point of amorphous Si is lower than the crystalline value is also seen. Annealing with ps duration laser pulses is reported. Pulsed ion‐beam irradiation is shown to be capable of removing defects, at least within 1 micron of a wafer surface, confirming the promise of this new form of beam‐annealing.

+

Show PACS

07.79.Cz	Scanning tunneling microscopes
61.05.-a	Techniques for structure determination
68.55.-a	Thin film structure and morphology
81.10.Jt	Growth from solid phases (including multiphase diffusion and recrystallization)
68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics

Select this Article

Laser annealing of bipolar NPN transistors

R. H. Hendel, D. D. Casey, and C. U. Bickford

J. Vac. Sci. Technol. 18, 818 (1981); http://dx.doi.org/10.1116/1.570954 (3 pages) | Cited 1 time

Full Text: | Download PDF

+

Show Abstract

We present dc characteristics of a cw laser annealed bipolar transistor. Laser activation of the emitter implant results in β = 15 with V_CE = 10 V and I_C = 10 mA. Laser power absorption (laser in multiline mode), emitter profile modelling and emitter‐base junction protection are discussed.

+

Show PACS

85.30.Pq	Bipolar transistors
73.40.Lq	Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
61.72.U-	Doping and impurity implantation

Select this Article

Laser annealing of phosphosilicate glass

A. Naumaan and J. T. Boyd

J. Vac. Sci. Technol. 18, 821 (1981); http://dx.doi.org/10.1116/1.570955 (4 pages)

Full Text: | Download PDF

+

Show Abstract

Laser annealing of CVD layers of phosphosilicate glass (PSG) using a CO₂ laser (10.6 μm wavelength) has been investigated. Evidence of plastic flow of the PSG caused by laser heating was obtained. Reduction of surface and bulk defects in the PSG layers was ascertained by measurement of scattering losses, before and after annealing, of He–Ne radiation (632.8 μm) waveguiding in the layers. An improvement in attenuation of as much as 12 dB/cm was obtained.

+

Show PACS

42.60.-v	Laser optical systems: design and operation
81.40.Tv	Optical and dielectric properties related to treatment conditions
42.82.-m	Integrated optics
85.40.-e	Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology

Select this Article

Summary Abstract: Plasma–surface interactions in dry processing

J. W. Coburn and H. F. Winters

J. Vac. Sci. Technol. 18, 825 (1981); http://dx.doi.org/10.1116/1.570956 (2 pages)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

52.40.Hf	Plasma-material interactions; boundary layer effects
79.20.Rf	Atomic, molecular, and ion beam impact and interactions with surfaces
82.65.+r	Surface and interface chemistry; heterogeneous catalysis at surfaces

Select this Article

Materials options for field‐effect transistors

H. H. Wieder

J. Vac. Sci. Technol. 18, 827 (1981); http://dx.doi.org/10.1116/1.570957 (11 pages) | Cited 2 times

Full Text: | Download PDF

+

Show Abstract

The evolution of monolithic high‐speed digital and analog microwave field‐effect transistor (FET) technologies is linked inextricably to synthesis, control, and understanding of the properties of the semiconducting binary, ternary, and quaternary III–V compounds. It is also linked to the application and use of ion implantation as a pivotal corollary process. Selection of a Schottky barrier, insulated‐gated or heterojunction gate technology defines, in part, the options available in terms of the fundamental surface and interfacial properties of these compounds. Others concern electron transport processes under surface depletion, inversion and accumulation regimes, and the solution of metallurgical problems involved in the formation of ohmic and blocking contacts, the free carrier concentration and mobility profiles, and their stability as a function of process variables used to make such FET.

+

Show PACS

73.40.-c	Electronic transport in interface structures
73.61.-r	Electrical properties of specific thin films
72.20.-i	Conductivity phenomena in semiconductors and insulators
85.30.-z	Semiconductor devices

Select this Article

Sputtered TiW/Au Schottky barriers on GaAs

L. S. Weinman, S. A. Jamison, and M. J. Helix

J. Vac. Sci. Technol. 18, 838 (1981); http://dx.doi.org/10.1116/1.570958 (3 pages) | Cited 6 times

Full Text: | Download PDF

+

Show Abstract

High quality stable Schottky barriers are required for GaAs diodes and MESFETS used in mixers and analog and digital ICs. The TiW/Au system has been shown to be quite stable on GaAs. TiW/Au Schottky barriers were deposited on bulk GaAs by rf diode and rf magnetron sputtering. In addition, Ti/W/Au Schottky barriers were deposited by rf magnetron sputtering and e‐beam deposition. Capacitance–voltage and current–voltage measurements, along with Auger analysis were done to determine diode quality. A marked improvement in barrier height and reverse bias characteristics (I–V) was obtained by utilizing magnetron sputtering and reducing deposition power. Free carrier profiles showed evidence of some damage, even at extremely low power levels.

+

Show PACS

73.30.+y	Surface double layers, Schottky barriers, and work functions
73.40.Ns	Metal-nonmetal contacts
81.15.Cd	Deposition by sputtering

Select this Article

Summary Abstract: Thin film and package processing aspects of Josephson LSI

B. J. van der Hoeven

J. Vac. Sci. Technol. 18, 841 (1981); http://dx.doi.org/10.1116/1.570973 (2 pages)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

74.50.+r	Tunneling phenomena; Josephson effects
85.25.-j	Superconducting devices

Select this Article

Oxidation of Si(111), 7×7 and 2×1: A comparison

C. Y. Su, P. R. Skeath, I. Lindau, and W. E. Spicer

J. Vac. Sci. Technol. 18, 843 (1981); http://dx.doi.org/10.1116/1.570974 (4 pages) | Cited 4 times

Full Text: | Download PDF

+

Show Abstract

The initial processes of oxygen adsorption on the 2×1 and 7×7 Si(111) surfaces are studied in detail with photoemission techniques. The high‐energy resolution and high surface sensitivity Si‐2p core level spectra have revealed clearly the different nature of the oxygen adsorption processes on the two surfaces. Analysis of the oxidation properties of the 7×7 surface gives strong support for ’’defect’’‐type models of the 7×7 structure.

+

Show PACS

79.60.-i	Photoemission and photoelectron spectra
73.20.-r	Electron states at surfaces and interfaces
81.65.-b	Surface treatments

Select this Article

The Si(111) 7×7 to ’’1×1’’ transition: A summary

M. B. Webb and P. A. Bennett

J. Vac. Sci. Technol. 18, 847 (1981); http://dx.doi.org/10.1116/1.570975 (5 pages)

Full Text: | Download PDF

+

Show Abstract

This paper summarizes a low‐energy electron diffraction study of the Si(111) 7×7 to ’’1×1’’ transitions. Excess diffuse scattering appears during the transition and demonstrates that the transition is to a disordered selvedge at high temperatures. The long‐range order shows critical behavior for reduced temperature between 0.93 and 0.99 with a critical exponent β = 0.11 ± 0.15 which is similar to values for 2d Ising and Potts models but distinctly different from the mean‐field values. Critical scattering with properties similar to those for mean‐field or 2d Ising models is not observed. The relaxation time for ordering diverges near T_c but the disordering kinetics remain faster than the experimental time constant of .05 s.

+

Show PACS

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)
64.70.K-	Solid-solid transitions
64.60.F-	Equilibrium properties near critical points, critical exponents

Select this Article

Atomic structure of laser annealed Si(111)–(1×1)

D. M. Zehner, J. R. Noonan, H. L. Davis, and C. W. White

J. Vac. Sci. Technol. 18, 852 (1981); http://dx.doi.org/10.1116/1.570976 (4 pages) | Cited 7 times

Full Text: | Download PDF

+

Show Abstract

Although the stable surface structure of a clean, thermally annealed Si(111) is a (7 × 7) at room temperature, a metastable (1 × 1) structure can be obtained by irradiating the crystal with the output of a pulsed ruby laser. The structural determination of this atomically clean (1 × 1) arrangement is important since it may subsequently be used as a basis for the eventual understanding of the (7 × 7) reconstruction. A LEED analysis of the (1 × 1) structure is reported in which I–V profile data for the six lowest indexed nonspecular beams have been collected with the incident electron beam normal to the surface. These experimental profiles have been compared with the results of dynamical calculations, in which the first and second interlayer spacings of the truncated bulk model were varied. Also, nonstructural parameters have been varied in the calculations. The results suggest a bulklike layer termination exhibiting no ordered lateral reconstruction with the first interlayer spacing contracted by 25.5±2.5% and the second expanded by 3.2±1.5% with respect to bulk values. The best comparison between calculated and experimental I–V profiles has produced a six‐beam Zanazzi and Jona R‐factor of 0.115.

+

Show PACS

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

Select this Article

Theoretical studies of Si(111) surface structures

D. J. Chadi

J. Vac. Sci. Technol. 18, 856 (1981); http://dx.doi.org/10.1116/1.570977 (4 pages) | Cited 3 times

Full Text: | Download PDF

+

Show Abstract

A brief discussion of the 1×1, 2×1, and 7×7 reconstructed surfaces of Si(111) is given. The emphasis is on surface atomic geometry and its effect on electronic and chemical properties of the surface.

+

Show PACS

68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics
73.20.-r	Electron states at surfaces and interfaces
61.05.jh	Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
68.35.Md	Surface thermodynamics, surface energies

Select this Article

Electronic states of Si(111) surfaces

F. Houzay, G. M. Guichar, R. Pinchaux, and Y. Petroff

J. Vac. Sci. Technol. 18, 860 (1981); http://dx.doi.org/10.1116/1.570978 (6 pages) | Cited 1 time

Full Text: | Download PDF

+

Show Abstract

The purpose of this paper is to review recent angle resolved photoemission measurements on cleaved 2×1 and 7×7 reconstructed surfaces using the polarization properties of synchrotron radiation. The similarity of the results for the two reconstructions (weak or no metallic edge, symmetry of the dangling bond surface state) will be discussed as a function of the different theoretical models.

+

Show PACS

81.65.-b	Surface treatments
73.20.-r	Electron states at surfaces and interfaces
61.66.Bi	Elemental solids
61.05.jh	Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)

Select this Article

Analysis of low‐energy electron diffraction intensities from ZnS(110)

C. B. Duke, R. J. Meyer, A. Paton, A. Kahn, J. Carelli, and J. L. Yeh

J. Vac. Sci. Technol. 18, 866 (1981); http://dx.doi.org/10.1116/1.570979 (5 pages) | Cited 1 time

Full Text: | Download PDF

+

Show Abstract

Preliminary results for the atomic geometry of the (110) surface of ZnS are reported. The surface structure is determined by comparing dynamical calculations of elastic low‐energy electron diffraction (ELEED) intensities with those measured at T = 300 K using a pulsed floodgun technique to suppress the charging of the insulating ZnS sample. In contrast to other tetrahedrally‐coordinated, zincblende‐structure compound semiconductors for which the (110) surfaces are known to be reconstructed, i.e., GaAs, InSb, InP, and ZnTe, the measured ELEED intensities from ZnS(110) are described acceptably by calculations based on the truncated bulk atomic geometry and minor variants thereof. Measures of the quality of this description of the ELEED intensity data are the x‐ray reliability (R) factor, R_x = 0.222, and the Zanazzi–Jona R‐factor, R_ZJ = 0.229. The minimum x‐ray R‐factor which we have achieved thus far, i.e., R_x = 0.219, is obtained for a puckered surface geometry in which the sulfur species relaxes vertically upward by 0.06 Å and the zinc species vertically upward by 0.02 Å. While we believe that the surface structure can be refined further, the quality of the description of the measured ELEED intensities by atomic geometries in the vicinity of the unreconstructed surfaces is surprisingly good relative to previously‐studied zincblende‐structure compound semiconductors.

+

Show PACS

73.20.-r	Electron states at surfaces and interfaces
79.20.Fv	Electron impact: Auger emission
61.05.jh	Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
81.65.-b	Surface treatments

Select this Article

Summary Abstract: Si(111)‐7×7 surface structure using ion scattering

R. J. Culbertson, L. C. Feldman, and P. J. Silverman

J. Vac. Sci. Technol. 18, 871 (1981); http://dx.doi.org/10.1116/1.570980 (1 page)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics
79.20.Rf	Atomic, molecular, and ion beam impact and interactions with surfaces
61.85.+p	Channeling phenomena (blocking, energy loss, etc.)

Select this Article

Structure study of Au–Si interface by MeV ion scattering

T. Narusawa, K. Kinoshita, W. M. Gibson, and A. Hiraki

J. Vac. Sci. Technol. 18, 872 (1981); http://dx.doi.org/10.1116/1.570981 (4 pages) | Cited 3 times

Full Text: | Download PDF

+

Show Abstract

An application of the MeV ion backscattering/channeling technique to the Au–Si interface problem is described in this report. It is directly shown that at room temperature both Si(100) and Si(111) surfaces interact with deposited Au atoms abruptly if the Au film thickness exceeds a critical value of ∠4 monolayer (ML). The interface structure is similar in both cases and consists of ∠2 ML of strained Si and ∠10 ML of disordered (amorphous) silicide layer. When the substrate temperature is kept at 550°C during Au‐film deposition, the interfacial reaction occurs if the average Au‐film thickness reaches 1 ML in the Au–Si(111) system and ∠2 ML in the Au–Si(100) system. This is a suggestion of interaction between Si dangling bonds and the first few monolayers of Au‐film.

+

Show PACS

68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics
73.30.+y	Surface double layers, Schottky barriers, and work functions
73.40.-c	Electronic transport in interface structures
79.60.Jv	Interfaces; heterostructures; nanostructures

Select this Article

Binding state perturbations in the silicon oxide–tungsten system

O. K. T. Wu and Richard P. Burns

J. Vac. Sci. Technol. 18, 876 (1981); http://dx.doi.org/10.1116/1.570982 (4 pages)

Full Text: | Download PDF

+

Show Abstract

Thin films of silicon dioxide are widely used in present day microelectronic devices. In this study we investigate the model system silicon oxide adsorbed on clean and oxidized polycrystalline tungsten. The adsorbed silicon oxide is formed by means of an SiO molecular beam, and the adsorbate‐surface interactions are studied by means of Auger Electron Spectroscopy and Flash Desorption Mass Spectrometry. We find that the binding state of SiO on a W surface can be perturbed by electron beam irradiation and also by oxygen coadsorption. The electron beam desorbs oxygen from the SiO+W system, but Si is not desorbed. After electron bombardment and annealing at 613 K, the single binding state of SiO on W(oxidized) is converted into two states. One state is characteristic of SiO on W(clean), while the other is characteristic of SiO on W(oxidized). In addition, oxygen coadsorption induces changes in the flash desorption spectrum of SiO. An analysis of the desorption spectrum indicates that the coadsorption process leads to attractive interactions between adsorbate and adsorbate. Thus, we conclude that the binding between the silicon oxide and the metal substrate is very sensitive to the film stoichiometry.

+

Show PACS

68.43.-h	Chemisorption/physisorption: adsorbates on surfaces
68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics
68.60.-p	Physical properties of thin films, nonelectronic
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Select this Article

Si(111): Ni surface studies by AES, UPS, LEED, and ion scattering

Y. J. Chabal, R. J. Culbertson, L. C. Feldman, and J. E. Rowe

J. Vac. Sci. Technol. 18, 880 (1981); http://dx.doi.org/10.1116/1.570983 (3 pages)

Full Text: | Download PDF

+

Show Abstract

We have studied the Si(111) surface after various heat treatments with small amounts of Ni (?1 monolayer) present. We find that three types of reconstructions can be obtained: 7×7, ’’1×1’’ and √19×√19. Photoemission spectra show that the metallic nature of the dangling bond surface state, characteristic of the clean 7×7 surface, disappears for the ’’1×1’’ and √19×√19 surfaces. MeV ion scattering establishes that the average surface atom displacement parallel to the surface is significantly larger for the √19×√19 surface than for both the clean 7×7 and the ’’1×1’’ surfaces.

+

Show PACS

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)
81.65.-b	Surface treatments
73.20.-r	Electron states at surfaces and interfaces

Select this Article

Transient capacitance spectroscopy of semiconductor/insulator interface states: Thermally activated capture cross section of Si/SiO₂ interface states

E. Kamieniecki, N. Gomma, A. Kloc, and R. Nitecki

J. Vac. Sci. Technol. 18, 883 (1981); http://dx.doi.org/10.1116/1.570984 (5 pages) | Cited 7 times

Full Text: | Download PDF

+

Show Abstract

A modified transient capacitance technique is introduced which is capable of characterizing continuously distributed semiconductor/insulator interface states. Using this technique, Si/SiO₂ interface states located in the upper half of the Si bandgap have been studied in n‐type MOS structures. In agreement with previous reports, it was found that the interface state density continuously increase towards the conduction band edge. The interface state density close to mid‐gap was about 10¹⁰ eV⁻¹ cm⁻². For the first time, it was experimentally shown that the electron capture cross section, σ_n, of the interface states located in the upper half of the bandgap is thermally activated, i.e., described by the formula σ_n = σ_o exp(−ΔE/kT), where σ_o?3×10⁻¹⁷ cm² is independent of temperature and the energy location of the interface states. The observed decrease of the activation energy ΔE(10–40 meV in the energy range 0.3–0.1 eV below the conduction band). The observed interface states are shown to be indentical with the ’’ion‐electron (configurational) interface states’’ whose existence was suggested previously from conductance and photocapacitance measurements of Si–MOS structures.

+

Show PACS

73.40.Qv	Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.20.-r	Electron states at surfaces and interfaces

Select this Article

Studies on silicon MOS Schottky barriers

F. A. Abou‐Elfotouh

J. Vac. Sci. Technol. 18, 888 (1981); http://dx.doi.org/10.1116/1.570985 (2 pages) | Cited 2 times

Full Text: | Download PDF

+

Show Abstract

Aluminum–silicon oxide‐p‐type silicon solar cells were prepared and their characteristic performance was investigated as a function of the properties of the transition layer at the Si/Si oxide interface, material parameters of the substrate, and postoxidation annealing. Improved F_f and P_o were observed in samples with low carbon content (<10¹⁴ cm⁻³) and high oxygen concentration (10¹⁸ cm⁻³). Current suppression was smaller in Li and Al doped substrates than in B doped materials at critical concentrations of 10¹⁸ and 5×10¹⁷ cm⁻³, respectively. Prolonged annealing and high temperature oxidation are also desired.

+

Show PACS

73.30.+y	Surface double layers, Schottky barriers, and work functions
73.40.Qv	Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
84.60.Jt	Photoelectric conversion
85.30.Hi	Surface barrier, boundary, and point contact devices

Select this Article

Process conditions affecting hot electron trapping in dc magnetron sputtered MOS devices

N. A. Bojarczuk

J. Vac. Sci. Technol. 18, 890 (1981); http://dx.doi.org/10.1116/1.570986 (5 pages) | Cited 5 times

Full Text: | Download PDF

+

Show Abstract

Process parameters affecting hot electron trapping in MOS capacitors produced by magnetron sputtered aluminum were studied. The electron traps considered are process induced and affected by changes in sputtering parameters. Devices were fabricated under each of the following varying conditions: target presputter time, deposition power, source to substrate distance, process pressure, deposition thickness, anode bias voltage, and annealing temperature. Mobile ion concentration, surface state, and flatband voltage measurements revealed values less than 4×10¹⁰ charges/cm², 3.7×10¹⁰ states/cm² eV, and −1.2 V after a 400°C anneal in 10% H₂/90% N₂ forming gas mixture. Hot electron injection measurements of the devices after the same anneal resulted in minimum effective electron trapping (4.25×10¹⁰ electrons/cm² trapped for 9×10¹⁴ electrons/cm² injected) when the process conditions were optimized. The optimized parameters reduced the trapping density and improved device performance.

+

Show PACS

61.80.-x	Physical radiation effects, radiation damage
81.15.Cd	Deposition by sputtering
73.40.Qv	Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
52.25.Os	Emission, absorption, and scattering of electromagnetic radiation

Select this Article

Detection of residual damage in ⁷⁵As implanted silicon single crystal by secondary ion mass spectrometry

A. C. Yen

J. Vac. Sci. Technol. 18, 895 (1981); http://dx.doi.org/10.1116/1.570987 (4 pages)

Full Text: | Download PDF

+

Show Abstract

Radiation damage occurred in single crystalline silicon during ⁷⁵As ion implantation at 50 keV and could not be annealed out completely at 1000 °C for 30–70 min. Part of the damaged volume was recrystallized by this 1000 °C thermal treatment. The other part, with a relatively low level of damage, did not recrystallize but acted as a sink for trapping impurities during annealing. In the case of implantation into silicon covered with a thin (225 Å) layer of silicon dioxide, secondary ion mass spectrometry showed a different ⁷⁵As in‐depth profile as compared with the case of implantation into bare silicon. Additional annealing, after implantation, was added in both cases. Recoiled oxygen from the SiO₂ layer segregated into the region with residual damage during thermal annealing and enhanced the ionization yield of ⁷⁵As. The diffusion depth of arsenic was found to be affected by the retained damage and trapped oxygen.

+

Show PACS

61.80.Jh	Ion radiation effects
61.72.U-	Doping and impurity implantation
81.40.Ef	Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
82.80.Ms	Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Select this Article

Effect of ion implantation on CdSe thin film transistors

F. R. Shepherd, W. D. Westwood, P. J. Scanlon, J. Levinson, I. V. Mitchell, and H. Plattner

J. Vac. Sci. Technol. 18, 899 (1981); http://dx.doi.org/10.1116/1.570988 (4 pages)

Full Text: | Download PDF

+

Show Abstract

Thin film transistors have been fabricated by implanting 50 keV Cr, 50 keV Al, and 15 keV B ions into high resistivity (≳10⁵Ωcm), polycrystalline CdSe deposited by thermal evaporation. The implants were made at room temperature into inverted transistor structures fabricated by photoengraving. Both the Cr and Al implants cause a maximum decrease of approximately 1.5% in the c‐axis lattice spacing of CdSe, and enhance the (00.1) texture of the grains. Similar but smaller changes in c were observed in B implanted samples. For a fixed CdSe film thickness of ∠800 Å, the drain current, I_D, increases rapidly with implant dose above the unimplanted value (∠10 nA). At a dose of 5×10¹⁵cm⁻², I_D was approximately 200 μA (V_D = 10 V, V_G = 10 V) for the Cr and B implants but was much higher for Al; I_D was 1.9 mA at V_D = 0.5 V for the same V_G. The current‐dose dependence is interpreted in terms of filling of grain boundary traps by implanted donors, with the intergrain potential barrier height determined by the implant dose.

+

Show PACS

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
85.30.Tv	Field effect devices

Select this Article

Summary Abstract: Electronic structure of the V/Si interface

J. G. Clabes and G. W. Rubloff

J. Vac. Sci. Technol. 18, 903 (1981); http://dx.doi.org/10.1116/1.570989 (2 pages)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

73.40.Ns	Metal-nonmetal contacts
73.30.+y	Surface double layers, Schottky barriers, and work functions
79.60.-i	Photoemission and photoelectron spectra
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Select this Article

Summary Abstract: Site‐specific densities of states for cleaved and sputtered GaAs (110) from Auger line shapes

G. D. Davis, D. E. Savage, and M. G. Lagally

J. Vac. Sci. Technol. 18, 904 (1981); http://dx.doi.org/10.1116/1.570990 (2 pages)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

79.20.Fv	Electron impact: Auger emission
71.20.-b	Electron density of states and band structure of crystalline solids
61.72.-y	Defects and impurities in crystals; microstructure
68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics

Select this Article

Summary Abstract: Growth of high quality epitaxial GaAs films by sputter deposition

S. A. Barnett, G. Bajor, and J. E. Greene

J. Vac. Sci. Technol. 18, 906 (1981); http://dx.doi.org/10.1116/1.570991 (2 pages) | Cited 1 time

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

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
68.55.-a	Thin film structure and morphology
81.15.Cd	Deposition by sputtering
81.15.-z	Methods of deposition of films and coatings; film growth and epitaxy

Select this Article

Summary Abstract: Oxygen adsorption on Si(110) studied by Auger electron spectroscopy

P. Morgen

J. Vac. Sci. Technol. 18, 908 (1981); http://dx.doi.org/10.1116/1.570992 (2 pages)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

82.65.+r	Surface and interface chemistry; heterogeneous catalysis at surfaces
79.20.Fv	Electron impact: Auger emission
73.40.Qv	Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Select this Article

Silicide interface stoichiometry

J. L. Freeouf

J. Vac. Sci. Technol. 18, 910 (1981); http://dx.doi.org/10.1116/1.570993 (7 pages) | Cited 3 times

Full Text: | Download PDF

+

Show Abstract

Recent studies of the initial stages of silicide formation on silicon have observed a chemical shift of silicide‐like valence orbitals. The sign of the shift suggests a silicon‐rich ’’silicide’’ close to the silicon substrate smoothly grading to the bulk silicide stoichiometry as the probed region is moved away from the substrate. Such results suggest a re‐examination of the boundary values appropriate to a simple Schottky picture of the metal‐semiconductor interface. It seems clear that the appropriate metal workfunction is that of the metallic region closest to the silicon‐i.e., the region most deviant from the bulk silicide. The absence of reliable experimental values for either stoichiometry or the workfunciton of this region forces us to model both. Assuming the silicon electron affinity and doping to be unaffected by the interface, we conclude that such a silicon excess would reduce the dependence of barrier height upon bulk metal (silicide) workfunction. Further, we conclude that if this metallic layer has a stoichiometry very silicon‐rich (∠(metal)Si₄) the barrier height of most silicides would be fully explained by this effect and the Schottky picture of the interface.

+

Show PACS

73.30.+y	Surface double layers, Schottky barriers, and work functions
68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics
61.50.Nw	Crystal stoichiometry

Select this Article

Metal–semiconductor interfacial reactions: Ni/Si system

N. W. Cheung, P. J. Grunthaner, F. J. Grunthaner, J. W. Mayer, and B. M. Ullrich

J. Vac. Sci. Technol. 18, 917 (1981); http://dx.doi.org/10.1116/1.570994 (7 pages) | Cited 14 times

Full Text: | Download PDF

+

Show Abstract

Interfacial reactions between Si and deposited metals have been investigated by x‐ray photoelectron spectroscopy (XPS) and channeling measurements with MeV ⁴He ions. This paper is concerned with reactions of Ni deposited at 10⁻¹⁰ Torr on clean Si and with the structure of the interface in the Si/Ni₂Si/Ni structure. Both XPS and channeling measurements show that reactions occur where Ni is deposited at 10⁻¹⁰ Torr on Si: Si atoms are displaced from lattice sites, the Ni atoms are in an Si‐rich environment, and the Ni/Si interface is graded in composition. Composition gradients are present at both interfaces in the Si/Ni₂/Si/Ni system: at the Si/Ni₂Si interface Ni atoms are in a more Si‐rich environment than that found for Ni in Ni₂Si or NiSi and at the Ni/Ni₂Si interface Si atoms are in more Ni‐rich environment than that found for Si in Ni₂Si. In both deposited Ni on Si and the Si/Ni₂Si/Ni structures, Ni atoms are found at the tetrahedral interstitial site in Si. For the Ni–Si system, cooling the substrate to ∠100 K slows down the reaction rate. The temperature dependence of the interfacial reactivity indicates the kinetic nature of metal–semiconductor interfaces.

+

Show PACS

68.55.-a	Thin film structure and morphology
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
33.60.+q	Photoelectron spectra

Select this Article

Interface metallurgy and electronic properties of silicides

G. Ottaviani

J. Vac. Sci. Technol. 18, 924 (1981); http://dx.doi.org/10.1116/1.570995 (5 pages) | Cited 9 times

Full Text: | Download PDF

+

Show Abstract

In spite of extensive experimental and theoretical investigations our understanding of Schottky barrier formation between a metal and silicon is far from complete. Studies have been conducted on a wide range of metals and compounds and the data spread over a large range. Historically, the first kind of measurements were electrical; later, metallurgical properties were investigated; and recently, new techniques as UPS and XPS have been applied. We critically review the experimental data, trying to identify the main parameters affecting the electrical behavior of the metal–semiconductor interface. We conclude that all the data support the hypothesis of an interfacial layer between silicon and metal (or silicides). The interfacial layer is responsible for the electrical as well as for the metallurgical behavior of the system. To support the model we use barrier height measurements concepts developed in studying compound formation and data obtained with photoemission spectroscopy on monolayer and submonolayer metal deposition on silicon.

+

Show PACS

61.66.Dk	Alloys
81.30.Bx	Phase diagrams of metals, alloys, and oxides
68.55.-a	Thin film structure and morphology
73.30.+y	Surface double layers, Schottky barriers, and work functions

Select this Article

Surface defect effects on Schottky barriers

R. H. Williams

J. Vac. Sci. Technol. 18, 929 (1981); http://dx.doi.org/10.1116/1.570959 (8 pages) | Cited 28 times

Full Text: | Download PDF

+

Show Abstract

Over the years a number of different mechanisms have been proposed to account for Schottky barrier formation at metal–semiconductor interfaces. The application of modern surface analytical techniques to study such interfaces has recently shown that the influence of surface and near surface defects in the semiconductor, can, in many instances, dominate the mechanism of barrier formation. This is believed to be particularly true for metals on clean cleaved (110) surfaces of III–V semiconductors. In this article we consider the evidence in support of the defect model. We consider chemical reactions and interdiffusion effects which may occur when metals are deposited and we consider the possible microscopic nature of the defects so formed and their influence on barrier formation. We also consider experimental and theoretical studies when clean semiconductor surfaces are subjected to controlled contamination prior to the deposition of the metal contact and how these, in general, support the defect model.

+

Show PACS

73.30.+y	Surface double layers, Schottky barriers, and work functions
73.40.Ns	Metal-nonmetal contacts
73.20.Hb	Impurity and defect levels; energy states of adsorbed species
78.40.Fy	Semiconductors

Select this Article

Electronic states and atomic structure at the Pd₂Si–Si interface

P. E. Schmid, P. S. Ho, H. Föll, and G. W. Rubloff

J. Vac. Sci. Technol. 18, 937 (1981); http://dx.doi.org/10.1116/1.570960 (7 pages) | Cited 11 times

Full Text: | Download PDF

+

Show Abstract

Electronic states and atomic structure at the Pd₂Si–Si interface have been investigated using AES and UPS in conjunction with transmission electron microscopy (TEM). By following the core and valence spectra from submonolayer to several atomic layers of Pd coverages, the changes in the partial state density of the Pd and Si atoms during interface formation have been observed. Stoichiometry calibration based on relative variation of Auger intensities reveals extra Si states existing within a few Å of the interface. Analysis of the spectral shapes and peak shifts shows that these Si states are derived from a Si‐rich environment at the interface and are located mostly near the Si bandgap region. TEM lattice images reveal a structurally sharp Pd₂Si–Si (111) interface with misfit dislocations and atomic steps present within several Å of the interface. Combining the spectroscopy and TEM results, we infer that the interface states originate from chemical bonds associated with the atomic defect structures produced by silicide formation.

+

Show PACS

73.40.-c	Electronic transport in interface structures
73.20.-r	Electron states at surfaces and interfaces
73.40.Sx	Metal-semiconductor-metal structures
85.30.Hi	Surface barrier, boundary, and point contact devices

Select this Article

XPS investigation of the oxidation of Hg_1−xCd_xTe surfaces

S. P. Kowalczyk and J. T. Cheung

J. Vac. Sci. Technol. 18, 944 (1981); http://dx.doi.org/10.1116/1.570961 (5 pages) | Cited 17 times

Full Text: | Download PDF

+

Show Abstract

X‐ray photoelectron spectroscopy (XPS) was employed to characterize the oxidation of Hg_1−xCd_xTe surfaces. Surfaces investigated included those treated with a standard Br‐methanol etch and atomically clean surfaces produced by low‐energy ion bombardment. The latter type surfaces were exposed to controlled amounts of dry oxygen and laboratory ambient. The main observation on all surfaces investigated was preferential TeO₂ formation at the surface. Oxidation of the atomically clean surfaces under dry conditions was found to proceed very slowly. Some surfaces were treated with simple organic acids. These surfaces upon exposure to ambient for several weeks exhibited very little or no TeO₂ growth.

+

Show PACS

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

Select this Article

Effects of a thin SiO₂ layer on the formation of metal–silicon contacts

S. M. Goodnick, M. Fathipour, D. L. Ellsworth, and C. W. Wilmsen

J. Vac. Sci. Technol. 18, 949 (1981); http://dx.doi.org/10.1116/1.570962 (6 pages) | Cited 8 times

Full Text: | Download PDF

+

Show Abstract

The reactions that occur between different metals and silicon wafers with a thin oxide layer have been investigated. The oxides were formed by either exposing the chemically cleaned wafer to air at room temperature or by thermally growing 30 Å of oxide at 700 °C in dry O₂. Al, Pt, and Au contacts were investigated. The interfacial reactions before and after heat treatment at 400 °C for 1 h were characterized using Auger and ESCA sputter profiling. The air grown oxides were found not to prevent intimate contact between the metal and the silicon, and reactions were observed for both heat treated and unheated samples. At 400 °C the 30 Å thermal oxide was found to be an effective diffusion barrier for Pt but less effective for Au. The Al reduced the 30 Å of SiO₂ to form Al₂O₃ at the interface in what appeared to be a self‐limiting reaction. A comparison between the reactions observed on air grown oxides and 30 Å of thermally grown oxide are consistent with observations that the room temperature oxides are not as fully formed as oxides grown at 700 °C.

+

Show PACS

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
85.30.Hi	Surface barrier, boundary, and point contact devices
81.40.-z	Treatment of materials and its effects on microstructure, nanostructure, and properties

Select this Article

Variations in the stoichiometry of thin oxides on silicon as seen in the Si LVV Auger spectrum

H. S. Wildman, R. F. Bartholomew, W. A. Pliskin, and M. Revitz

J. Vac. Sci. Technol. 18, 955 (1981); http://dx.doi.org/10.1116/1.570963 (5 pages) | Cited 1 time

Full Text: | Download PDF

+

Show Abstract

Oxides less than 30 Å thick were formed on single crystal silicon by O₂ plasma ashing, exposure to hot H₂SO₄, and thermal oxidation and were characterized by Auger electron spectroscopy, ellipsometry, and infrared transmission spectroscopy. Other studies have shown that Si atoms bonded to fewer than four oxygen atoms contribute to Auger peaks with energies between the 90 eV and 74 eV LVV peaks of Si and SiO₂. These results were used to detect deviations from stoichiometry in the SiO₂ films from the shape of the LVV peak. Electron beam irradiation enhanced an 83 eV component. Our LFE Model 1002 O₂ plasma asher produced less stoichiometric oxides than our Model 301 asher. Some of the oxides were further characterized by their ability to mask phosphorous diffusion from a doped polysilicon source. Deviations from stoichiometry partially explained the reduced ability of oxides from the Model 1002 asher and oxides grown in H₂SO₄ to mask the phosphorous diffusion.

+

Show PACS

79.20.Ds	Laser-beam impact phenomena
61.50.Nw	Crystal stoichiometry
66.30.J-	Diffusion of impurities
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)

Select this Article

A study of the initial oxidation of polycrystalline Si using surface analysis techniques

L. L. Kazmerski, O. Jamjoum, P. J. Ireland, and R. L. Whitney

J. Vac. Sci. Technol. 18, 960 (1981); http://dx.doi.org/10.1116/1.570964 (5 pages) | Cited 6 times

Full Text: | Download PDF

+

Show Abstract

The initial oxidation of polycrystalline Si is studied in order to determine differences in oxide growth at grains and grain boundaries. Auger electron spectroscopy is used to spatially resolve the surface oxidation that has been performed in situ in the UHV analysis chamber under controlled temperature and pressure conditions. Angular‐resolved x‐ray photoelectron spectroscopy provides information on the composition and thickness of the oxides. The transition layer between the SiO₂ and Si is estimated to be in the range of 4–15 Å, depending upon the region in which it is measured. Comparisons of these angular‐resolved XPS data are made between single grain and grain boundary regions.

+

Show PACS

81.65.-b	Surface treatments
82.65.+r	Surface and interface chemistry; heterogeneous catalysis at surfaces
79.60.-i	Photoemission and photoelectron spectra

Select this Article

Thermal nitridation of Si(111) by nitric oxide

M. D. Wiggins, R. J. Baird, and P. Wynblatt

J. Vac. Sci. Technol. 18, 965 (1981); http://dx.doi.org/10.1116/1.570965 (6 pages) | Cited 15 times

Full Text: | Download PDF

+

Show Abstract

Clean Si(111) surfaces were thermally nitrided at various temperatures by exposure to low pressures (1×10⁻⁶ Torr) of NO in a UHV system. The nitridation process was monitored by multiple surface analytical techniques including AES, XPS, UPS, LEED, and thermal desorption. At substrate temperatures below 800°C a silicon oxynitride was formed in which the nitrogen to oxygen ratio increased with increasing reaction temperature. These oxynitride films were converted to nitride films by loss of O and SiO when heated to temperatures greater than 850°C in vacuum. Exposure of the clean Si to NO at temperatures greater than 1000°C produced an oxygen‐free nitride film. The nitride films formed by either route gave the ’’doublet’’ LEED pattern which has previously been associated with the formation of a two domain epitaxial α‐Si₃N₄ layer. Due to the high reactivity of NO, the presence of 20%–30% C on the Si surface was not necessary for nucleation sites as had been reported for nitridation by NH₃.

+

Show PACS

68.55.-a	Thin film structure and morphology
79.20.Fv	Electron impact: Auger emission
81.65.-b	Surface treatments

Select this Article

Summary Abstract: Auger sputter profiling studies of SiO₂ grown in O₂/HCl mixtures

J. W. Rouse, C. R. Helms, B. E. Deal, and R. R. Razouk

J. Vac. Sci. Technol. 18, 971 (1981); http://dx.doi.org/10.1116/1.570966 (2 pages)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

81.65.-b	Surface treatments
85.30.De	Semiconductor-device characterization, design, and modeling
79.20.Fv	Electron impact: Auger emission

Select this Article

Summary Abstract: MeV ion scattering studies of the(111)Si−SiO₂ interface

R. Haight, W. M. Gibson, T. Narusawa, and L. C. Feldman

J. Vac. Sci. Technol. 18, 973 (1981); http://dx.doi.org/10.1116/1.570967 (1 page)

Full Text: | Download PDF

Abstract Unavailable

+

Show PACS

68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics
81.65.-b	Surface treatments
61.85.+p	Channeling phenomena (blocking, energy loss, etc.)

Select this Article

A 10¹³/s 14 MeV neutron generator for cancer therapy

R. J. Walko, F. M. Bacon, R. W. Bickes, D. F. Cowgill, J. E. Boers, A. A. Riedel, and J. B. O’Hagan

J. Vac. Sci. Technol. 18, 975 (1981); http://dx.doi.org/10.1116/1.570968 (8 pages) | Cited 1 time

Full Text: | Download PDF

+

Show Abstract

A high output D‐T neutron generator is being developed at Sandia National Laboratories as a cancer therapy tool. Preliminary results have been obtained with a high vacuum deuterium accelerator consisting of a duopigatron ion source, single stage accelerator, and a scandium occluder target. The ion source and accelerating system have been optimized to reliably focus a 200 mA, 200 kV deuterium ion beam onto the scandium target 1.5 m away with a beam spot size of 10⁻³m². The scandium target degrades due to implantation of impurities from the unbaked vacuum system. A UHV accelerator is being fabricated which will permit a 450 °C bakeout to alleviate the impurity problem. This system will also be compatible with the use of tritium, a necessary component of the therapy machine.

+

Show PACS

29.25.Dz	Neutron sources
52.75.Di	Ion and plasma propulsion
87.50.C-	Static and low-frequency electric and magnetic fields effects

Select this Article

Ion beam characteristics of a gas‐filled accelerator tube

R. S. Berg, R. W. Bickes, J. E. Boers, and L. A. Shope

J. Vac. Sci. Technol. 18, 983 (1981); http://dx.doi.org/10.1116/1.570969 (4 pages)

Full Text: | Download PDF

+

Show Abstract

A gas‐filled tube used to produce a pulsed neutron flux with the D(T,He⁴)n reaction is described. Deuterium and tritium ions generated in a reflex discharge are extracted and accelerated to 100 keV by means of an accelerator electrode onto a deutero–tritide target electrode. The electrodes are designed to focus the ion beam onto the target. Total tube currents consisting of extracted ions, unsuppressed secondary electrons, and ions generated by interactions with the background gas are typically 100 mA. Characteristics of the extracted ion beam are discussed. Accelerating voltages greater than 50 keV are required to focus the beam through the accelerator aperture for configurations that give beams with the proper energy density at the target. The perveance of the beam is defined. Maximum perveance values are 2–10 nanopervs. Tube focussing and neutron production characteristics are described.

+

Show PACS

41.75.Ak	Positive-ion beams
41.75.Cn	Negative-ion beams
52.40.Mj	Particle beam interactions in plasmas

Select this Article

Measurement of ion energy distribution in an orbitron device

M. L. Feidt and B. Petit

J. Vac. Sci. Technol. 18, 987 (1981); http://dx.doi.org/10.1116/1.570970 (7 pages) | Cited 1 time

Full Text: | Download PDF

+

Show Abstract

The ion energy distribution in an orbitron device has been measured by means of a retarding field analyzer. The influence of the main geometric and electric parameters of the device on the ion spectra is reported here. The observed distributions show that, because of the electrostatic field configuration, the ionizing efficiency is much smaller near the reflector plates than in the central part of the device. In all cases the ion energy distribution is continuous and broad with a single maximum. Implications of the electron distribution in the orbitron are discussed. Particularly, it results from these investigations that the radial electron density distribution is a monotonically decreasing function of the radial position in the orbitron. These results are interpreted in terms of electron trajectories.

+

Show PACS

52.80.Vp	Discharge in vacuum
07.30.-t	Vacuum apparatus
84.47.+w	Vacuum tubes

Select this Article

Nitrogen sensitivities of a sample of commercial hot cathode ionization gage tubes

K. E. McCulloh and C. R. Tilford

J. Vac. Sci. Technol. 18, 994 (1981); http://dx.doi.org/10.1116/1.570971 (3 pages) | Cited 1 time

Full Text: | Download PDF

+

Show Abstract

In order to help assess the magnitude of errors that might arise from the use of uncalibrated ionization gage tubes and help select the best type of tube when accurate measurements are required we have determined the nitrogen sensitivities from 10⁻⁵ to 10⁻² Pa for lots of from two to four each of five different types of commerical hot cathode gage tubes. Included were conventional triodes and B‐A structures of four distinct types. Two types with tungsten filaments—the triodes and tubulated B‐A structures—were markedly superior to the others with respect to agreement with manufacturer’s sensitivity, linearity, and uniformity of sensitivity within a type. The least satisfactory results were obtained from the nude B‐A structures, which showed significant nonlinearities, sensitivities ranging from 70%–110% of the manufacturer’s value, and typical 25% differences in sensitivity between the two filaments of a dual‐filament structure.

+

Show PACS

07.30.Dz

Vacuum gauges

Select this Article

Selection and evaluation of an ultrahigh vacuum gate valve for ISABELLE beam line vacuum system

C. L. Foerster and D. McCafferty

J. Vac. Sci. Technol. 18, 997 (1981); http://dx.doi.org/10.1116/1.570972 (4 pages)

Full Text: | Download PDF

+

Show Abstract

A minimum of 84 ultrahigh vacuum gate valves will be utilized in ISABELLE to protect proton beam lines from catastrophic vacuum failure and to provide sector isolation for maintenance requirements. The valve to be selected must function at less than 1×10⁻¹¹ Torr (1.3×10⁻⁹ Pa) and be bakeable to 300 °C in its open or closed position. In the open position, the valve must have an rf shield to make the beam line walls appear continuous. Several proposed designs were built and evaluated. The evaluation consisted mainly of leak testing, life tests, thermal cycling, mass spectrometer analysis, and 10⁻¹² Torr operation. Problems with initial design and fabrication were resolved. Special requirements for design and construction were developed. This paper describes the tests on two final prototypes which appear to be the best candidates for ISABELLE operation.

+

Show PACS

29.20.db	Storage rings and colliders
07.30.Hd	Vacuum testing methods; leak detectors

Select this Article

Evaluation of ISABELLE full cell ultrahigh vacuum system

C. L. Foerster, J. Briggs, T. S. Chou, and P. Stattel

J. Vac. Sci. Technol. 18, 1001 (1981); http://dx.doi.org/10.1116/1.570872 (4 pages)

Full Text: | Download PDF

+

Show Abstract

The ISABELLE full cell vacuum system, consisting of a 40 m long by 8.8 cm diam stainless steel tube pumped by seven pumping stations, was assembled and processed for 10⁻¹² Torr operation. Evaluation and testing of the system and its subassemblies has been completed. Detail design of system components and the determination of the conditioning process was completed. The best procedure to rough pump, leak test, vacuum bake the system, condition pumps, degas gauges, turn on ion pumps, and flash sublimation pumps was established. Pressures below 2×10⁻¹¹ Torr are now routinely achieved in normal operation of the full cell. This includes pump down after replacement of various components and pump down after back fill with moist unfiltered air. The techniques developed for the full cell will be used to build the ISABELLE ultrahigh vacuum system.

+

Show PACS

29.20.db	Storage rings and colliders
07.30.Hd	Vacuum testing methods; leak detectors

Select this Article

Application of low temperature calorimetry for the measurement of impingement rate of gas molecules

I. Arakawa and Y. Tuzi

J. Vac. Sci. Technol. 18, 1005 (1981); http://dx.doi.org/10.1116/1.570873 (4 pages)

Full Text: | Download PDF

+

Show Abstract

Calorimetric measurement of the heat generated by condensation of gases on a cryosurface was applied to determine the impingement rate of gas molecules and the molecular density in gas phase. This method can be applied to the absolute measurement of pressure. The calorimeter, on which gases were condensed, was mounted on a liquid helium cryostat and calibrated by using an electric heater attached. The relations between the rate of heat generation and the rate of condensation were measured for Ar, Kr, Xe, CH₄, N₂, and CO₂. Linear relations were found within the accuracy of measurement in the range from 10⁻⁵ to 10⁻³ Pa m³/s of the rate of condensation, when the temperature of gases was 300 K and that of the cryosurface was about 7.5 K. Experimental results and thermodynamically calculated ones agreed with systematic error of about 5% for all gases examined except CO₂. Anomalous behavior CO₂ is thought to be caused by its condensation process.

+

Show PACS

07.20.Fw	Calorimeters
07.30.Dz	Vacuum gauges
68.03.Fg	Evaporation and condensation of liquids
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)

Select this Article

A simple understanding of net outgassing rate as a function of pumping speed

G. Horikoshi and M. Kobayashi

J. Vac. Sci. Technol. 18, 1009 (1981); http://dx.doi.org/10.1116/1.570874 (4 pages) | Cited 2 times

Full Text: | Download PDF

+

Show Abstract

Recently, some experimental results show that the outgassing rate depends largely on the pumping speed of the system. For a complete understanding of these facts, a simplifed model was proposed and an experiment was performed. In the model, we consider only one kind of diffusion process from the inside of the bulk and one kind of adsorption and desorption processes with a sojourn time τ₁. In practice, we can only measure the net outgassing rate, i.e., the difference between the incident flux and flux out of the surface. When the surface is exposed to an absolute vacuum, the incident flux is zero and the outgassing rate is equal to the flux out of the surface, which is much larger than the observed outgassing rate in practice. Analysis shows that the outgassing rate depends not only on the pumping speed of the system but also on the surface conditions, such as the surface density of adsorbed gas molecules and their sojourn time, and finally approaches an intrinsic value for the material. The experimental results show a good agreement with the theory.

+

Show PACS

07.30.Bx	Degasification, residual gas
47.45.Gx	Slip flows and accommodation

Select this Article

Performance of a simplified directional detector for gas molecules

M. Kobayashi, Y. Tuzi, and K. Terada

J. Vac. Sci. Technol. 18, 1013 (1981); http://dx.doi.org/10.1116/1.570875 (4 pages) | Cited 3 times

Full Text: | Download PDF

+

Show Abstract

A simplified directional detector for gas molecules was developed which does not use the collimator, described in a previous article,¹ but has bundled capillaries at the entrance of the detector. The detector’s performance with capillaries is analyzed and compared with some experimental results. The directivity depends on the pumping speed of the bell jar, as in the case of the collimator, and on the length‐to‐diameter ratio of the capillary. The directivity of the detector can be increased ∠20 times or more than that of the detector with an orifice of the same diameter. Response time of the detector can be reduced by increasing the number of the capillaries. This detector has been applied to the measurement of the angular distributions of desorbed H₂ molecules from Si (111) surfaces.

+

Show PACS

07.30.-t	Vacuum apparatus
07.75.+h	Mass spectrometers
47.45.Dt	Free molecular flows
68.43.-h	Chemisorption/physisorption: adsorbates on surfaces

Select this Article

Measurement of neutral gas density with ionization gauges in plasma physics research

A. Berman

J. Vac. Sci. Technol. 18, 1017 (1981); http://dx.doi.org/10.1116/1.570876 (6 pages) | Cited 1 time

Full Text: | Download PDF

+

Show Abstract

The assessment of neutral gas density in the vicinity of a magnetically confined plasma is necessary for the consideration of atomic processes in fusion research experiments. Ionization gauges can be used provided that steps are taken to restrict the influence of the magnetic field on their sensitivity and to effect the differentiation of the true signal from the plasma produced background. In addition, the gauges must have a rather short time constant and a large signal‐to‐noise ratio. This paper presents an analysis of the features mentioned, based on a careful review of the literature to date. The results achieved by different research workers are discussed within the frame of the foregoing analysis. An attempt to correlate the design criteria underlying the operation of ionization gauges used in plasma machines is presented.

+

Show PACS

07.30.Hd	Vacuum testing methods; leak detectors
07.30.Dz	Vacuum gauges
07.07.Df	Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.50.-e	Electrical and electronic instruments and components

Select this Article

Water vapor pressure gauge

D. Edwards and D. Gillette

J. Vac. Sci. Technol. 18, 1023 (1981); http://dx.doi.org/10.1116/1.570877 (3 pages)

Full Text: | Download PDF

+

Show Abstract

An inexpensive pressure gauge, able to measure the N₂ and H₂O components within a vacuum system in the pressure range 1 to 400 μ is described and results of tests of the device are reported.

+

Show PACS

07.30.Dz	Vacuum gauges
07.20.-n	Thermal instruments and apparatus

Select this Article

Pumping of corrosive or hazardous gases with turbomolecular and oil‐filled rotary vane backing pumps

K. Fischer, J. Henning, K. Abbel, and H. Lotz

J. Vac. Sci. Technol. 18, 1026 (1981); http://dx.doi.org/10.1116/1.570878 (4 pages)

Full Text: | Download PDF

+

Show Abstract

Since at high‐vacuum pressure the gas density is low, no real problems occur while pumping, e.g., corrosive or even explosive media by means of turbomolecular pumps. New problems arise from pumping radioactive gases like tritium. Here the turbomolecular pumps have to be adapted to the fact that the leakage from the pump’s interior to the ambient has to be kept as low as possible. Backing pumps have to pump higher gas densities. Some corrosive or hazardous gases can be pumped with standard pumps using special pump fluids. Many other applications, however, require protective measures to guarantee acceptable lifetimes of the vacuum equipment. The paper describes the necessary pumps and accessories to meet the requirements of safely pumping vapors and gases in the processes of plasma etching, plasma deposition, low pressure CVD, and explosive gas mixtures.

+

Show PACS

07.30.Cy	Vacuum pumps
81.65.-b	Surface treatments
82.35.-x	Polymers: properties; reactions; polymerization

Select this Article

Mechanical boosters on clean or corrosive applications

N. T. M. Dennis, L. J. Budgen, and L. Laurenson

J. Vac. Sci. Technol. 18, 1030 (1981); http://dx.doi.org/10.1116/1.570879 (3 pages) | Cited 2 times

Full Text: | Download PDF

+

Show Abstract

This paper discusses in detail the methods that are adopted to either reduce contamination of the oil in the coupling and gears from corrosive vapors in the system, or conversely ensure that the oil vapors cannot reach the high vacuum system. The method of sealing the mechanical booster pump interior from the oil boxes is described and the alternative ways of pumping these boxes are shown. The vacuum that can be achieved above a mechanical booster taking these precautions is given and the level of organic vapors determined by using both a quadrupole mass spectrometer and a quartz crystal microbalance.

+

Show PACS

07.30.Kf	Vacuum chambers, auxiliary apparatus, and materials
07.75.+h	Mass spectrometers

Select this Article

Vacuum pumping of aggressive and dust laden vapors

P. Connock, A. Devaney, and I. Currington

J. Vac. Sci. Technol. 18, 1033 (1981); http://dx.doi.org/10.1116/1.570880 (4 pages)

Full Text: | Download PDF

+

Show Abstract

The equipment required to pump systems which evolve dust, corrosive or solvent materials is discussed. The types of filter available to stop dust reaching the mechanical pump are described and their effect on pumping speed is quantified. Chemical traps to considerably reduce vapors reaching the rotary pump are described and the absorptive capacity of materials used in these traps under vacuum conditions has been investigated and the results are reviewed. The use of an external oil filter fitted to the pump oil circulation system is discussed with reference to handling capacity, in particular for acidic vapors.

+

Show PACS

07.30.-t

Vacuum apparatus

Select this Article

Material selection for TFTR limiters

M. Ulrickson

BROWSE VOLUMES

Apr 1981

Volume 18, Issue 3, pp. 677-1322