JVST Banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Sep 1973

Volume 10, Issue 5, pp. 599-896


Superconductivity and Metastable Phases in Thin Films

Werner Buckel

J. Vac. Sci. Technol. 10, 599 (1973); http://dx.doi.org/10.1116/1.1318397 (4 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
Results on quenched condensed films of Bi, Sb, Sb+noble metals, Ge, Ge+noble metals, and Sn+Cu are discussed in order to demonstrate the importance of the short-range order for the properties of such films. Two kinds of amorphous films can be clearly distinguished: (a) crystallinelike and (b) liquidlike amorphous films. This classification is important for materials which are partially covalently bonded. The results also show that an interesting relation exists between metastable phases in quenched condensed films and high pressure modifications of the same material.
Show PACS
74.78.-w Superconducting films and low-dimensional structures
68.55.Nq Composition and phase identification

Normal State Nucleation Times in Superconductors

Robert Peters and Hans Meissner

J. Vac. Sci. Technol. 10, 603 (1973); http://dx.doi.org/10.1116/1.1318398 (3 pages)

Full Text: | Download PDF

Show Abstract
Both dc and rf currents are passed through a thin narrow film of tin such that the total current exceeds the critical current ic. Lowering the rf frequency from 1 GHz causes, at a reproducible frequency ωc, a step in the rf voltage away from the superconducting state toward the normal state. Increasing the dc increases ωc in accord with the empirical relation: idc+irf exp(−ωcτ)=ic. The time constant τ, which is a measure of the normal state nucleation time, is about 10−9 sec and is a function of temperature and of irf. Second harmonics and phase shifts were observed.
Show PACS
74.78.-w Superconducting films and low-dimensional structures
74.25.F- Transport properties

Tunneling Studies of the Formation of Intermetallic Compounds in Gold–Lead Films

A. F. Hebard

J. Vac. Sci. Technol. 10, 606 (1973); http://dx.doi.org/10.1116/1.1318399 (5 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
The possibility of forming the gold–lead intermetallic compounds Au2Pb, AuPb2 and AuPb3 in tunnel structures using thin films of aluminum, aluminum oxide, lead, and finally gold is being studied. The room temperature diffusion of gold into lead films with thickness in the range 1000–3600 Å is found to be rapid, with indications of compound formation taking place within a few hours. Variation of the thickness ratio of the lead and gold films is used to preferentially form a given intermetallic. Each intermetallic is characterized by its transition temperature Tc, energy gap Δo, and by a unique phonon spectrum which is reflected in the derivatives of the tunneling characteristics.
Show PACS
68.35.Fx Diffusion; interface formation

Superconductivity of Transition Metal Thin Films Deposited by Noble Gas Ion Beam Sputtering

P. H. Schmidt

J. Vac. Sci. Technol. 10, 611 (1973); http://dx.doi.org/10.1116/1.1318400 (5 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
Noble gas ion beam sputtering techniques have been used to prepare thin films of several transition metals. Thin films of Mo, Ti, W, and Zr metals have been found to be superconducting with transition temperatures substantially higher than those observed for the respective bulk metals. Cr thin films have been found to be superconducting for the first time. Ion beam sputtered thin films of Nb, Ru, Ta, and V metals were similarly deposited, resulting in decreases in Tc compared with bulk values. In each case the transition temperatures were seen to depend on the noble gas used for deposition. The highest transition temperatures were obtained for those films deposited with xenon gas. Superconducting transition temperatures are correlated with the kind of gas used for deposition, the apparent particle size, and with changes in the size of the metal lattice.
Show PACS
74.78.-w Superconducting films and low-dimensional structures
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
81.15.Cd Deposition by sputtering

rf Sputtered Luminescent Rare-Earth Oxysulfide Films

T. G. Maple and R. A. Buchanan

J. Vac. Sci. Technol. 10, 616 (1973); http://dx.doi.org/10.1116/1.1318401 (5 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
Thin luminescent films of lanthanum and gadolinium oxysulfide (RE2O2S) were prepared by radio-frequency sputtering in an Ar–H2S mixture. Small additions of Eu, Tb, or Tm produced red, green, or blue emissions, respectively. A luminance of 40 000 ftL from a La2O2S:Tb film was observed. The composition of the sputtered films was found to be very dependent upon the H2S pressure in the sputtering chamber. The film composition as a function of H2S pressure was determined and described. In order to achieve maximum luminescence, the films were treated in an H2–SO2 atmosphere at 1000 °C, and x-ray diffraction and luminous emission linewidths were observed to have decreased after treatment. Crystalline growth within the film and improved oxygen sulfur stoichiometry resulting from the treatment process are believed to be primarily responsible for the increase in luminous efficiency. The maximum luminous efficiency of the films was measured to be approximately 1∕10 that of corresponding powder screens. Attempts to increase the film luminance by reducing the internal trapping of the radiation are discussed.
Show PACS
78.66.-w Optical properties of specific thin films
68.55.-a Thin film structure and morphology
68.60.Dv Thermal stability; thermal effects
81.15.Cd Deposition by sputtering

Crystal Structure of Evaporated MgO Films on Amorphous and Polycrystalline Substrates

M. O. Aboelfotoh

J. Vac. Sci. Technol. 10, 621 (1973); http://dx.doi.org/10.1116/1.1318402 (5 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
Thin films of MgO were prepared by deposition from the vapor phase on amorphous and pylycrystalline substrates. Transmission and reflection electron diffraction were used to determine the orientation of the crystals in these MgO films. It was found that, on amorphous substrates initially at room temperature, the films possessed a crystal orientation which varied with film thickness. Films thinner than ∼ 500 Å showed a random orientation. As the film thickness was increased above ∼ 500 Å, a [111] preferred orientation was developed with an axis inclined away from the substrate normal and toward the direction of the vapor beam at oblique vapor incidence. At high substrate temperature (∼150–300 °C), the films followed the same behavior during growth. This preferred orientation is interpreted as a final growth orientation. On silver films as substrates, initially at room temperature, the same [111] preferred orientation was observed in films ≲ 100 Å thick and with increasing film thickness the orientation persisted. In thick deposits a slight inclination of the orientation axis was also observed at oblique vapor incidence. These results suggest that on Ag substrates the orientation is an initial nucleation orientation and also a final growth orientation.
Show PACS
68.55.-a Thin film structure and morphology
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Inelastic Tunneling in Pb–Zn or ZnS–Oxide–Pb Junctions

P. W. Wyatt, R. C. Barker, and A. Yelon

J. Vac. Sci. Technol. 10, 626 (1973); http://dx.doi.org/10.1116/1.1318403 (5 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
A series of tunneling measurements using Pb–Zn or ZnS–oxide–metal thin film junctions in the normal state is reported. The samples are prepared by depositing a film of Zn or ZnS on top of the first Pb film prior to oxidation. For both dopants a metallic Zn layer of monolayer thickness is present between the Pb and the insulator. A fraction of a monolayer of Zn is sufficient to substantially enhance the structure usually attributed to electrode phonons and to eliminate that usually attributed to PbOx barrier phonons. The latter is replaced by structure which may be related to ZnO in Zn-doped junctions and ZnS in one type of ZnS-doped junctions. No barrier phonon structure whatever appears in a second type of ZnS-doped junction. The smooth background conductance is also modified by the doping. These results are discussed in terms of recent theoretical work. They suggest that the coupling to barrier and electrode phonons is at least as important in determining the tunneling characteristic as the phonon spectra themselves, and that the metal-insulator interface is critical in determining the coupling.
Show PACS
73.40.Gk Tunneling
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials

Magnetic Thin Films for Optical Storage

Kenneth Lee

J. Vac. Sci. Technol. 10, 631 (1973); http://dx.doi.org/10.1116/1.1318404 (9 pages) | Cited 6 times

Full Text: | Download PDF

Show Abstract
The magneto-optical properties of magnetic materials in thin film form have been of considerable interest since thermal magnetic recording was demonstrated on MnBi. With the advances being made in materials research and laser technology, a laser addressed system may be realized. Material requirements necessary for thermal magnetic recording are discussed. A review is made of those materials whose magnetic and optical properties have been studied. By comparing the known material properties with the required properties for a laser addressed memory, this review shows that, at present, four recently discovered compounds have satisfactory properties for an optical storage system. These four are high temperature phase MnBi doped with Ti or Ni for stabilization, MnAlGe, MnGaGe, and amorphous GdCo5.
Show PACS
75.50.Ss Magnetic recording materials
78.20.Ls Magneto-optical effects
75.70.Ak Magnetic properties of monolayers and thin films
78.66.Bz Metals and metallic alloys

The Study of Periodic Magnetic Structures by Diffraction Analysis

R. P. Ferrier, J. N. Chapman, and N. Toms

J. Vac. Sci. Technol. 10, 640 (1973); http://dx.doi.org/10.1116/1.1318405 (6 pages)

Full Text: | Download PDF

Show Abstract
In trying to determine the nature of the magnetization distribution in thin films having a periodic magnetic structure it is more convenient to work with the “magnetic” small angle diffraction pattern obtained in the electron microscope rather than the Lorentz image. The reasons for this will be discussed and two approaches to the analysis of the diffraction patterns will be described. The first method makes use of models of the magnetization distribution from which theoretical diffraction patterns may be computed for comparison with the observed data. The second method makes use of the Gerchberg-Saxton algorithm which may be applied directly to the intensity distribution in the diffraction pattern. The results of some preliminary studies using this algorithm will be discussed.
Show PACS
61.05.jd Theories of electron diffraction and scattering
75.70.Ak Magnetic properties of monolayers and thin films

Thin Film Superconducting Devices

J. E. Mercereau and H. A. Notarys

J. Vac. Sci. Technol. 10, 646 (1973); http://dx.doi.org/10.1116/1.1318406 (6 pages)

Full Text: | Download PDF

Show Abstract
Techniques have been developed with which it is possible to fabricate superconducting thin film structures (“bridges”) which show Josephson-like phenomena, with a wide variety of electrical and superconducting parameters. These bridges—based on the proximity effect—are made in layered thin film substrates which have been fabricated from many different, both hard and soft, superconducting materials. The fabrication techniques and the electrical and superconducting characteristics for these proximity effect bridges including a simple low frequency (≤10 GHz) equivalent circuit will be discussed. These bridges have been incorporated into simple thin film circuits for use as galvanometers, magnetometers, gradiometers, detector arrays, etc. Extension of these techniques to more complex superconducting thin film bridge circuits including resistors, capacitors, and inductors will be indicated.
Show PACS
85.25.-j Superconducting devices
74.78.Fk Multilayers, superlattices, heterostructures

Fluxoid Properties in Superconducting Films

W. J. SooHoo and R. L. Coren

J. Vac. Sci. Technol. 10, 652 (1973); http://dx.doi.org/10.1116/1.1318407 (3 pages)

Full Text: | Download PDF

Show Abstract
Theoretical studies of surface proximity effects in thin film superconductors have indicated a significantly different fluxoid structure from bulk. These results have led to suggestions that the static arrangement and dynamic behavior of fluxoids in films also differ. No experimental studies of these features have been reported. For this study niobium films 100–700 Å thick were placed in one arm of a 9.5 GHz reflection bridge in a perpendicular magnetic field. The complex reflection coefficients yield complex surface impedances which can be interpreted in terms of dynamic fluxoid properties. Some suggestive features are noted.
Show PACS
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.25.N- Response to electromagnetic fields
74.78.-w Superconducting films and low-dimensional structures

Structures Grown by Molecular Beam Epitaxy

L. L. Chang, L. Esaki, W. E. Howard, R. Ludeke, and G. Schul

J. Vac. Sci. Technol. 10, 655 (1973); http://dx.doi.org/10.1116/1.1318408 (8 pages) | Cited 30 times

Full Text: | Download PDF

Show Abstract
The process of molecular beam epitaxy is described, and its application to compound semiconductors is discussed. Growths and properties of GaAs and GaAs-GaAlAs superlattice are presented.
Show PACS
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Study of Interface Phonons in Lamellar Eutectics

F. Proix, R. Racek, and M. Balkanski

J. Vac. Sci. Technol. 10, 663 (1973); http://dx.doi.org/10.1116/1.1318409 (2 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Infrared quasinormal reflectivity has been measured at room temperature betweeen 200 and 700 cm−1 on lamellar eutectic mixtures LiF-NaF. The samples were cut perpendicular to the lamellae and their period was 1 or 7 μ. The difference between the experimental curves and a “theoretical” reflectivity, which is a weighted sum of the reflectivity curves of the pure compounds, is attributed to the interfaces. The difference curves exhibit five peaks, three of which are centered near bulk frequencies of the compounds. The other two are interpreted as interface modes and their frequencies compare quite well with the theory.
Show PACS
78.30.Hv Other nonmetallic inorganics

Critical Phenomena in Films and Surfaces

Michael E. Fisher

J. Vac. Sci. Technol. 10, 665 (1973); http://dx.doi.org/10.1116/1.1318410 (9 pages) | Cited 30 times

Full Text: | Download PDF

Show Abstract
The theory of critical phenomena in films (and general systems of restricted geometry) is reviewed, introducing the critical point shift exponent λ and the rounding or crossover exponent θ=1∕ν, which describes the changeover from bulk behavior. The exponents α×, β×, and γ× for the surface corrections to bulk behavior are defined and discussed. The deficiencies of the “extrapolation” length concept, for representing the surface boundary conditions on the order parameter, are explained. Barber's recent scaling theory for surface properties is reformulated in terms of a gap exponent Δ1 for a surface field H1. In a range of exactly soluble models Δ1 equals ½; this is probably always a good approximation. The scaling relation β1=2−α−ν−Δ1 then predicts the critical behavior of the surface order. Comparisons of the theory are made with analytical and numerical work on Ising, Heisenberg, and spherical models and on ideal Bose fluid films. A table of exponents is presented.
Show PACS
68.60.Wm Other nonelectronic physical properties
68.35.Rh Phase transitions and critical phenomena
64.60.F- Equilibrium properties near critical points, critical exponents

Theory of Critical Behavior in Films

D. J. Bergman, Y. Imry, G. Deutscher, and S. Alexander

J. Vac. Sci. Technol. 10, 674 (1973); http://dx.doi.org/10.1116/1.1318411 (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
The critical behavior of a thin film which is an intermediate case between a two-dimensional and three-dimensional system is considered and its various modes of critical behavior analyzed. This is used to find scaling-type relations among the two-dimensional and three-dimensional critical indices. We show that a great deal of information on the critical behavior can be obtained from measurements of the thickness dependence of the amplitudes of the various critically diverging quantities.
Show PACS
68.60.Wm Other nonelectronic physical properties
64.60.F- Equilibrium properties near critical points, critical exponents

Enhancement of Superconductivity and Softening of Phonons in Superconducting Semiconductors

A. Benyon and A. D. C. Grassie

J. Vac. Sci. Technol. 10, 678 (1973); http://dx.doi.org/10.1116/1.1318412 (3 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
Following experiments on inhomogeneously doped semiconductors which exhibited an elevation of the superconducting transition temperature due to the softening of phonons associated with a phase transition, the phonon spectrum in these alloys of PbTe, SnTe, and GeTe has been computed and has been found to imply an elevation of Tc in the homogeneous alloys.
Show PACS
74.62.Dh Effects of crystal defects, doping and substitution
74.25.Kc Phonons

Some Experimental Effects in Films of Ordered Matter

E. Guyon

J. Vac. Sci. Technol. 10, 681 (1973); http://dx.doi.org/10.1116/1.1318413 (6 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
The existence of boundary layers, having properties different from the bulk, influences considerably the ordering properties of thin films of condensed matter. First, we will review the problem of size effects in superconducting as well as in superfluid helium films. Liquid crystals films offer another class of ordered systems in which similar concepts can be applied. The physicochemical understanding of the boundary effects (role of the elastic distortion and of the interfacial chemical energy) and the bulk ordering mechanisms will be discussed and the analogies with the previous low temperature examples studied in the framework of the Landau model of phase transitions. A direct approach of the dynamic behavior is also possible due to macroscopic relaxation times.
Show PACS
68.60.Wm Other nonelectronic physical properties
64.60.Cn Order-disorder transformations
67.25.bh Films and restricted geometries

Depolarization Field and Stability Considerations in Thin Ferroelectric Films

I. P. Batra, P. Wurfel, and B. D. Silverman

J. Vac. Sci. Technol. 10, 687 (1973); http://dx.doi.org/10.1116/1.1318414 (6 pages) | Cited 16 times

Full Text: | Download PDF

Show Abstract
It is shown that the polarization in a thin ferroelectric film is always incompletely compensated. The associated depolarization field significantly modifies the phase stability of a ferroelectric film of sufficiently small thickness. For a slightly conducting ferroeletric film sandwiched between metallic electrodes, the polarization and transition temperature are depressed below the bulk values but the order of the phase transition remains unchanged. With semiconducting electrodes, even the order of the phase transition is modified for a thin ferroelectric film. A critical point exponent is calculated in each case within the framework of the Landau Theory. The results are compared and contrasted with the findings for other cooperative phenomena.
Show PACS
77.80.B- Phase transitions and Curie point
77.55.-g Dielectric thin films
77.22.Ej Polarization and depolarization

Simplified Band Model of Ferromagnetic Thin Films

S. Szczeniowski, L. Wojtczak, and A. Sukiennicki

J. Vac. Sci. Technol. 10, 693 (1973); http://dx.doi.org/10.1116/1.1318415 (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
The formulation of a simplified one-band model of ferromagnetism, convenient for analytical discussion of thin film properties, is given. Basing on this model the main effects experimentally observed in thin films, such as one electron excitations; spin waves and spin wave resonances, spontaneous magnetization, and the problem of dead layers are discussed. Some new effects following from our model, which are connected with the band nature of its origin, are presented.
Show PACS
75.10.Lp Band and itinerant models
75.70.Ak Magnetic properties of monolayers and thin films

Granular Superconducting Films

G. Deutscher, M. Gershenson, E. Grünbaum, and Y. Imry

J. Vac. Sci. Technol. 10, 697 (1973); http://dx.doi.org/10.1116/1.1318416 (5 pages) | Cited 6 times

Full Text: | Download PDF

Show Abstract
The broadening and the decrease of the superconducting transition temperature observed in high resistivity films of granular aluminum is analyzed in terms of a critical fluctuation model. Detailed grain size measurements indicate that the enhanced transition temperature observed in lower resistivity films is due to changes in the electron-phonon coupling rather than to an excitonic mechanism.
Show PACS
74.78.-w Superconducting films and low-dimensional structures
74.62.Yb Other effects
74.81.Bd Granular, melt-textured, amorphous, and composite superconductors

Bound States in Normal-Metal—Superconductor Sandwiches: Magnetic Field Dependence and Estimate of Fermi Velocities in Zinc

J. M. Rowell

J. Vac. Sci. Technol. 10, 702 (1973); http://dx.doi.org/10.1116/1.1318417 (3 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
The pair potential well, produced in a normal metal by proximity with a superconductor, supports bound states which can be observed in a tunneling experiment. Such states have been observed in Pb∕Zn-zinc oxide-Pb, and the temperature dependence of the I–V characteristic has been reported. Here these experiments are continued, showing, in particular, the magnetic field dependence of the bound states. The dressed Fermi velocities along the c axis of zinc are estimated to range from 0.4×108 to 1.0×108 cm∕sec, but to obtain improved accuracy in this measurement cleaner and thicker Zn films are required.
Show PACS
74.78.Fk Multilayers, superlattices, heterostructures
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Electronic Quantum Effects in Small Particles

W. D. Knight

J. Vac. Sci. Technol. 10, 705 (1973); http://dx.doi.org/10.1116/1.1318418 (8 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
Theoretical predictions are summarized for the electronic energy levels and magnetic resonance behavior of small metallic particles containing a few thousand atoms or less. Spin pairing in particles containing an even number of electrons is observed by NMR for lithium and aluminum, which follow the orthogonal case. Copper, which follows the symplectic case, appears to exhibit spin orbit coupling of intermediate strength, giving rise to incomplete spin pairing at absolute zero. Observations of odd particle effects are reported for the above metals, and narrow CESR lines for small particles of lithium indicate partial quenching of surface scattering of the conduction electrons. Nuclear spin relaxation measurements on aluminum show effects of superconductor fluctuations. Relaxation measurements in copper are obscured by paramagnetic impurities. Some NMR linewidths appear to result primarily from paramagnetic impurities and RKKY spin density oscillations, which are quenched when spin pairing occurs, with corresponding decrease in linewidth below a critical temperature.
Show PACS
73.22.-f Electronic structure of nanoscale materials and related systems
76.60.Es Relaxation effects
76.30.Pk Conduction electrons

Electronic Structure of Ultrathin Transition and Noble Metal Films with Simple Metal Interfaces

Bernard R. Cooper

J. Vac. Sci. Technol. 10, 713 (1973); http://dx.doi.org/10.1116/1.1318419 (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
We have developed a technique within the framework of the Green's function method for calculating the changes in electronic structure of d-band metals associated with going from a bulk to an ultrathin (oligatomic) film geometry. The formal result making high quality calculations of this type practical is that the film problem with a vanishing wavefunction boundary condition has electronic eigenfunctions which, within the film boundaries, are identical to those of an appropriately defined three-dimensional periodic tetragonal complex lattice. The boundary where the wave functions are constrained to vanish can lie outside the physical boundary limiting the region where the potential corresponds to the d-band metal, and can vary with energy. This has enabled us to allow for electron leakage from the d-band metal film and accurately simulate either the situation of a d-band metal film suspended in vacuum, or the more experimentally realizable situation of an ultrathin film of a d-band metal with interfaces with a simple metal. We show results for the latter situation for a monlayer of copper. These calculations predict striking changes from bulk behavior in agreement with photoemission experiments.
Show PACS
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
71.15.-m Methods of electronic structure calculations

Ultrathin Multiply Connected Rhenium Films

R. T. Lewis

J. Vac. Sci. Technol. 10, 717 (1973); http://dx.doi.org/10.1116/1.1318420 (6 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
An extensive (> 10 μ) multiply connected ultrathin (∼2 nm) rhenium metal film can be formed on the internal surfaces of porous high area aluminas and silicas by simple chemical means, ac susceptibility measurements have been made on such samples in applied static magnetic fields at temperatures below the superconducting transition of the rhenium film. The results can be interpreted using a model of hollow thin-walled cylinders in which the cylinder diameter is a measure of the extent of multiply connectedness and the wall thickness is a measure of the film thickness. The susceptibility is observed to decrease much more rapidly with increasing ac measuring field than with increasing applied static field. It is assumed that the decrease with ac field is inversely proportional to the cylinder diameter, and the decrease with static field is inversely proportional to the wall thickness. Using this model, estimates from the susceptibility measurements are found to be consistent with independent estimates of the film thickness from x-ray diffraction line broadening and of the extent of multiply connectedness from the decrease in signal after grinding and screening the sample.
Show PACS
74.78.-w Superconducting films and low-dimensional structures
75.70.Ak Magnetic properties of monolayers and thin films

Field Effects in Extremely Thin Crystals of Bi8Te7S5

U. H. Grote and H. H. Soonpaa

J. Vac. Sci. Technol. 10, 723 (1973); http://dx.doi.org/10.1116/1.1318421 (2 pages)

Full Text: | Download PDF

Show Abstract
Field effect conductivity measurements have been performed on extremely thin crystals of Bi8Te7S5. Only the thinnest (5 atoms thick) crystals show an unusual behavior, which can be readily explained in terms of the Fermi sphere, which does not intersect quantized Fermi momentum levels at zero bias. It is shown that both the volume density of carriers and the spacing of quantized kF levels increase at the same rate with decreasing sample thickness; thus the limitation in the observability of quantized kF levels is in the areal carrier density σ that the dielectric material between the film and the gate will allow.
Show PACS
73.50.Fq High-field and nonlinear effects
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.61.-r Electrical properties of specific thin films

Optical Conduction Resonance in Discontinuous Metal Films

J. P. Marton

J. Vac. Sci. Technol. 10, 725 (1973); http://dx.doi.org/10.1116/1.1318422 (3 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Optical resonance absorption in discontinuous metal films is studied in the dipole approximation. In the free electron regime the phenomenon is closely related to plasma oscillations and can be treated analytically. When damping is present, approximations may be employed and the quantities of interest can still be expressed in closed form. In the interband transition region the free electron effects are further damped and the resonance frequency may be shifted. In this case no analytical treatment is practical. Real situations may be simulated, however, by adding a lightly damped oscillator term to the free electron dielectric function of the metal. A suitable choice of parameters can describe a real metal.
Show PACS
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Switching Phenomena in Thin Films

David Adler

J. Vac. Sci. Technol. 10, 728 (1973); http://dx.doi.org/10.1116/1.1318423 (11 pages) | Cited 27 times

Full Text: | Download PDF

Show Abstract
Of the two types of switching phenomena which characterize thin films of amorphous semiconductors, it is now generally acknowledged that memory switching is basically well understood, not only in principle, but in detail. On the other hand, threshold switching has been a subject of some controversy, and a plethora of mechanisms has been proposed. In this paper, equilibrium and high-field characteristics as well as switching properties of threshold-type material are reviewed, and the suggested mechanisms are critically analyzed in the light of recent experimental results.
Show PACS
73.50.Fq High-field and nonlinear effects

Amorphous Thin Films

C. Wood, L. R. Gilbert, R. Mueller, and C. M. Garner

J. Vac. Sci. Technol. 10, 739 (1973); http://dx.doi.org/10.1116/1.1318424 (5 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
The optical and transport properties of the binary amorphous systems Sb-Se, Ge-Se, and Ge-Te, have been investigated as a function of composition. Essentially the whole amorphous phase of each system was prepared in a single evaporation by an elongated substrate coevaporation technique. The optical band gap varied fairly smoothly between the values for amorphous end components. Most films exhibited lnσ vs T−1 relationships. Except for the Sb-Se system, the σ0 values lay in the hopping conductivity range. Those Ge-chalcogenide films showing lnσ vs T−(1/4) hopping conductivity behavior generally converted to a T−1 variation after annealing. The thermal activation energies and thermo-emf measurements showed the Fermi levels to be fixed well away from the band edges in the forbidden gap. Delocalization of states in the gap of α-Ge with increasing chalcogen content was not observed. The results have been interpreted in terms of chemical bonding.
Show PACS
78.66.Jg Amorphous semiconductors; glasses
73.61.Jc Amorphous semiconductors; glasses
73.20.-r Electron states at surfaces and interfaces

Substrate Effects in the Theory of Negative Differential Resistance

T. M. Hayes and D. D. Thornburg

J. Vac. Sci. Technol. 10, 744 (1973); http://dx.doi.org/10.1116/1.1318425 (4 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
Current-controlled negative differential resistance under the constraint of uniform current flow is shown to result from the incorporation of realistic boundary conditions in solving for the steady-state electrical and thermal behavior of a Joule heated semiconducting thin film mounted on a substrate. The thermal conductance of the substrate, which is a necessary feature of the experimental situation, is shown to influence significantly the measured properties of the film-substrate combination. An analytic expression is induced for the voltage at the onset of negative differential resistance (the turnover voltage), and is demonstrated to be an approximate solution of the model for all values of substrate thermal conductance. The predictions of this model are shown to be consistent with experimental measurements of the threshold voltage as a function of film thickness and of ambient temperature.
Show PACS
73.50.Fq High-field and nonlinear effects

Structural and Electrical Properties of Evaporated-Amorphous and Vitreous-Amorphous V-VI Compounds

D. G. Ast

J. Vac. Sci. Technol. 10, 748 (1973); http://dx.doi.org/10.1116/1.1318426 (5 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
It is not widely realized that the structure of evaporated films differs significantly from the structure of vitreous bulk specimens. The atomic arrangement of vitreous specimens retains the short range order of the liquid from which they were prepared, whereas evaporated films are built up by the individual arrival of molecules and hence are inherently more random. The composition of these molecules depends on the composition of the evaporant and the evaporation conditions. Inspection of the radial distribution functions (RDF) of evaporated As2S3, As2Se3, and As2Te3 show consistently the appearance of an additional peak in the RDF of evaporated films. The peak is absent in the vitreous form and disappears when evaporated films are annealed in the vicinity of the glass transition temperature. These structural differences are reflected in the electronic properties of evaporated and vitreous samples.
Show PACS
68.55.-a Thin film structure and morphology
73.61.Jc Amorphous semiconductors; glasses
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Abstracts from the Proceedings of the Conference on Thin Film Phenomena

J. Vac. Sci. Technol. 10, 753 (); http://dx.doi.org/10.1116/1.1493052 (2 pages) | Cited 1 time

Full Text: | Download PDF

Abstract Unavailable
Show PACS
68.60.Dv Thermal stability; thermal effects
68.55.Nq Composition and phase identification
81.15.Cd Deposition by sputtering

The Cathode Ray Tube Display: Why Use Anything Else?

L. K. Anderson

J. Vac. Sci. Technol. 10, 761 (1973); http://dx.doi.org/10.1116/1.1318431 (7 pages)

Full Text: | Download PDF

Show Abstract
The cathode ray tube (CRT), especially if the definition is extended to cover all electron-beam addressed display devices, both self-luminous and light-modulating types, remains preeminent in today's display world in spite of competition from a variety of newer laser beam and matrix addressed display technologies. In this paper, we examine some of the reasons for the CRTs success, give a few examples of its continuing adaptability, and speculate on those weak points which may let other technologies get a foot in the door.
Show PACS
84.47.+w Vacuum tubes

Flat Cathode Ray Tubes

Walter F. Goede

J. Vac. Sci. Technol. 10, 768 (1973); http://dx.doi.org/10.1116/1.1318432 (4 pages)

Full Text: | Download PDF

Show Abstract
The hope of achieving a flat screen television display has resulted in a substantial effort by a number of individuals and companies to develop such a display. However, the performance requirements of such a display present a significant challenge to any display technique attempting to displace the extremely versatile analog defection CRT. To date, no new display has demonstrated the ability to meet these stringent performance requirements, but some of these new devices indicate that with further development these goals may be achieved. This paper will review the performance characteristics of one of these new displays, called the Digisplay, a flat panel digitally addressed CRT. In addition to the principles of operation and special operating characteristics, the characteristics of a new 160×256 resolution element device (2.2 lines∕ mm resolution), which has been used to present live—full gray scale—television will be briefly discussed.
Show PACS
84.47.+w Vacuum tubes

Light-Emitting Diodes and Semiconductor Materials for Displays

C. J. Nuese, H. Kressel, and I. Ladany

J. Vac. Sci. Technol. 10, 772 (1973); http://dx.doi.org/10.1116/1.1318433 (17 pages)

Full Text: | Download PDF

Show Abstract
A review is presented of the operation and characteristics of electroluminescent p-n junctions which are specifically designed for incoherent emission in the visible region of the optical spectrum. Recombination mechanisms in direct- and indirect-bandgap semiconductors, optical losses and reliability, efficiency and brightness considerations, and material synthesis are treated in sufficient depth to understand their role in the over-all performance of visible-light-emitting diodes (LEDs). The paper is concluded with a summary of the state of the art for each of the various types of LEDs presently under development or commercially available.
Show PACS
85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence
81.05.-t Specific materials: fabrication, treatment, testing, and analysis

Electroluminescent Displays

A. Vecht

J. Vac. Sci. Technol. 10, 789 (1973); http://dx.doi.org/10.1116/1.1318434 (7 pages) | Cited 6 times

Full Text: | Download PDF

Show Abstract
A review is made of the electroluminescent panels that have been prepared using activated zinc sulfide. The materials control at all stages of preparation is stressed. The characteristics of ac, continuous dc and pulsed dc operation cells are compared. Improved maintenance in dc electroluminescent displays is shown in panels prepared from manganese activated zinc sulfide, coated with a conducting layer of copper sulfide. Other activator systems in zinc sulfide are described and possible new host lattices discussed. Red electroluminescence from manganese activated barium zinc sulfide is described.
Show PACS
85.60.Pg Display systems

Plasma Panels

Peter H. Haberland

J. Vac. Sci. Technol. 10, 796 (1973); http://dx.doi.org/10.1116/1.1318435 (8 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
Both the ac-plasma panel and the Self Scan (trademark) panel have found application in display systems. Color capability and different brightness levels have been demonstrated. Some device and design parameters for the panel are discussed, and the operation of the two types of display devices is analyzed.
Show PACS
52.75.-d Plasma devices

Liquid Crystal Displays

L. A. Goodman

J. Vac. Sci. Technol. 10, 804 (1973); http://dx.doi.org/10.1116/1.1318436 (20 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
The various steps in the application of liquid crystals to displays are reviewed. First, the general classifications of liquid crystals and some common compounds are presented. Then, electrode materials and techniques for cell construction are discussed. Next, the diverse surface orientation methods are discussed. The electro-optic effects are classified by origin, that is, whether they result solely from dielectric forces or from the combination of dielectric and conduction stimuli. Different techniques for addressing liquid crystal displays are given. Finally, present and future applications are mentioned.
Show PACS
42.79.Kr Display devices, liquid-crystal devices

Projection Color Television Displays

W. E. Good and T. T. True

J. Vac. Sci. Technol. 10, 824 (1973); http://dx.doi.org/10.1116/1.1318437 (7 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
Current projection television displays are achieved by direct projection from a small CRT or by controlling the light from a separate light source with a “light valve.” This paper briefly reviews the Swiss Eidophor three-gun color television light valve and, more fully, the recently announced single-gun color television sealed light valve developed by the General Electric Company.
Show PACS
07.07.Hj Display and recording equipment, oscilloscopes, TV cameras, etc.

The First Twenty Years of the American Vacuum Society

H. W. Schleuning

J. Vac. Sci. Technol. 10, 833 (1973); http://dx.doi.org/10.1116/1.1318438 (10 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
This year, 1973, is the twentieth anniversary of the formation of the American Vacuum Society, and it is thus appropriate to review the development and growth of the Society. This brief history describes the formation of the Society and the first year of its existence and lists the officers of the Society over the years and the location of annual symposia. Various activities of the Society are described such as the symposia, educational activities, publications divisions and sections, and scholarships and awards.
Show PACS
01.10.Hx Physics organizational activities

Sputtered Platinum as Substrate for Ferroelectric Film Deposition

S. F. Vogel and I. C. Barlow

J. Vac. Sci. Technol. 10, 843 (1973); http://dx.doi.org/10.1116/1.1318439 (4 pages)

Full Text: | Download PDF

Show Abstract
Strongly adherent platinum films, 0.5 μ thick, were obtained on single-crystal alumina (sapphire) and polycrystalline alumina chips by sputtering platinum first in oxygen, then in argon, and subsequently heating the films at 930 °C in air. The crystal structure and orientation, as well as the related topography of the films, were characterized by x-ray diffraction and scanning electron microscopy, respectively.
Show PACS
81.15.Cd Deposition by sputtering
77.55.-g Dielectric thin films
68.55.-a Thin film structure and morphology

Fabrication of 104 Bit Permalloy-First Magnetic Bubble Circuits on Epitaxial Garnet Chips

J. P. Reekstin, A. G. Lehner, F. Vratny, and G. W. Kammlott

J. Vac. Sci. Technol. 10, 847 (1973); http://dx.doi.org/10.1116/1.1318440 (5 pages)

Full Text: | Download PDF

Show Abstract
A major advantage of magnetic bubble devices currently under development is the relatively small number of processing steps involved in device fabrication. With the advent of low defect epitaxial garnet films capable of supporting magnetic bubbles with diameters of 6 μ and less it is now possible to fabricate circuits with a minimum feature size of 3.5 μ and a capacity of 104 bits directly on the epitaxial film with a likelihood of reasonable yields. The major processing problems related to the dielectric layer, permalloy film, and current-carrying conductors are discussed. Processed circuits have been studied with the aid of scanning electron micrographs which reveal etch pattern profiles and composite structural features arising from multiple depositions.
Show PACS
85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.

Performance of an Oxide Solid Electrolyte as a Vacuum Oxygen Partial Pressure Gauge

C. J. Mogab

J. Vac. Sci. Technol. 10, 852 (1973); http://dx.doi.org/10.1116/1.1318441 (7 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
Calcia stabilized zirconia of nominal composition Ca0.15Zr0.85O1.85 has been used as the electrolyte of a galvanic cell for quantitative measurements of oxygen pressure in a vacuum chamber over the range 1–10−7 Torr. The low pressure limit is determined both by permeation of oxygen through the electrolyte and interaction with active residual gases such as CO, H2, and hydrocarbons. The response of the cell to changes in oxygen pressure is dependent on the pressure and independent of the electrolyte temperature over the range 600–800 °C. The rate of approach to a steady-state following step changes in oxygen pressure over the range ≈10−7–10−4 Torr can be represented by the empirical equation (dE∕dt)αΔEm, where E is the cell emf, t is time, ΔE is the departure of the emf from the steady-state value, m=1 for step increases in pressure, and m=1.5 for step decreases in pressure. The time constant for relaxation following an increase in pressure has been measured as ≈[8×10−5∕PO2(Torr)] sec, where PO2 is the vacuum oxygen pressure.
Show PACS
82.45.-h Electrochemistry and electrophoresis

Gas Desorption Temperatures of Two Molecular Sieves

H. Craig Miller

J. Vac. Sci. Technol. 10, 859 (1973); http://dx.doi.org/10.1116/1.1318442 (3 pages)

Full Text: | Download PDF

Show Abstract
This paper considers the problem of finding the temperatures of the desorption maxima for various gases absorbed on 5A and 13X molecular sieves at pressures of the order of 100μ. The desorption temperatures were not found to be strong functions of pressure. The measured desorption temperatures (in K) were, for 5A molecular sieve, Ar-110, O2-108, N2-145, CH4-151, CO-187, CO2-249, and H2O-410∕430, and for 13X molecular sieve, Ar-103, O2-108, N2-137, CH4-137, CO2-255∕285, and H2O-400∕425. These temperatures were measured with rates-of-rise of temperature low enough to minimize errors caused by the actual sieve temperature lagging the measured temperature.
Show PACS
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Kinetics of Thermal Decomposition of TiH2

C. W. Schoenfelder and J. H. Swisher

J. Vac. Sci. Technol. 10, 862 (1973); http://dx.doi.org/10.1116/1.1318443 (9 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
The thermal decomposition rate of TiH2 over the temperature range 250–500 °C (523–773 K) in a continuously pumped vacuum system was found to be much slower than predicted from diffusion model calculations. The rate was insensitive to the presence of oxygen in the environment and on the specimen surface; however, small amounts of residual hydrogen in the chamber decreased the rate considerably. The rate controlling process appears to be the reaction between hydrogen atoms to form gaseous molecules on the surface. When specimens were decomposed in flowing helium, the rate was slower than in vacuum, indicating that diffusion of hydrogen through a gaseous boundary layer on the surface can control the rate when a second gas is present.
Show PACS
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Mass Spectrometer Calibration under Pulsed Molecular Flow Conditions: Sample Inlet Influences

W. L. Winterbottom

J. Vac. Sci. Technol. 10, 871 (1973); http://dx.doi.org/10.1116/1.1318444 (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
A model has been developed to describe the influence of a slit-type sampling system on the pressure response of a mass spectrometer. Under molecular flow conditions, a distorted pressure waveform response is predicted for a time dependent pressure variation. A quantitative comparison between experiment and model prediction is presented to demonstrate both the effect and a method for spectrometer calibration.
Show PACS
07.75.+h Mass spectrometers

Four Models of Electron Distribution in the Orbitron

P. R. Deichelbohrer

J. Vac. Sci. Technol. 10, 875 (1973); http://dx.doi.org/10.1116/1.1318445 (7 pages)

Full Text: | Download PDF

Show Abstract
As a guide to the design of orbitron pumps and gauges, the radial variation of electron number density is calculated for four models of angular and axial momentum distributions. Uniform angular momentum distribution (for fixed axial momentum) gives an almost constant density. Angular momentum distribution that varies as sin2 gives two peaks. Adding a uniform distribution of axial momentum decreases the density near the cathode such that the outer peak is removed from the two-peak model. Also, the density is approximately proportional to the electron speed near the cathode in the model with uniform distribution of angular momentum.
Show PACS
07.77.Ka Charged-particle beam sources and detectors
07.30.-t Vacuum apparatus

A Thermally Shielded Atmospheric Pressure Standard Leak Calibrator

J. R. Miller

J. Vac. Sci. Technol. 10, 882 (1973); http://dx.doi.org/10.1116/1.1318446 (8 pages)

Full Text: | Download PDF

Show Abstract
A method is described for the calibration of capillary and permeation standard leaks. The technique utilizes a capacitance manometer to detect the small pressure change in a defined volume caused by the influx of gas from a standard leak. Corrections are derived for the small volume changes which occur during manometer operation. All measurements are made at atmospheric pressure. A double-walled aluminum and copper cylinder design is utilized to decrease temperature related pressure changes. A limiting drift rate of approximately 4×10−8 Torr∕sec (Q=3×10−9 std cm3∕sec) in the manometer indication was traced to manometer diaphragm “microcreep.” A method to reduce this background to ≃6×10−10 std cm3∕sec is described. The unique aspect of the calibrator is its ability to calibrate Freon standard leaks under usage conditions, i.e., using Freon gas with atmospheric pressure on the down-stream side of the leak, down to 10−9 std cm3∕sec. Error of measurement ranges from +10% to 15%. Calibration results for several leaks are presented.
Show PACS
07.30.Hd Vacuum testing methods; leak detectors

Adsorption of Simple Particles onto a One Dimensional Lattice with Nearest Neighbor Interaction

R. B. McQuistan and S. J. Lichtman

J. Vac. Sci. Technol. 10, 890 (1973); http://dx.doi.org/10.1116/1.1318447 (3 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Using an exact expression for the occupied nearest neighbor degeneracy, the adsorption isotherm for a one dimensional lattice is calculated taking into account nearest neighbor interactions between adsorbing particles. The equation of state is also determined. It is also shown that the influence of coverage on the heat of adsorption is exactly that obtained using the Bethe approximation.
Show PACS
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

An Ionic Bonding Interpretation of the GaAs-(1̄ 1̄ 1̄) Surface (19)(1/2)×(19)(1/2)−23.4 ° LEED Reconstruction

Peter Mark

J. Vac. Sci. Technol. 10, 893 (1973); http://dx.doi.org/10.1116/1.1318448 (2 pages) | Cited 1 time

Full Text: | Download PDF

Abstract Unavailable
Show PACS
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)

Gasket Removal Groove

J. J. Donelon and John M. Baker

J. Vac. Sci. Technol. 10, 894 (1973); http://dx.doi.org/10.1116/1.1318449 (1 page)

Full Text: | Download PDF

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

Comments on “Some Special Pumping Problems Associated with the Sputtering Application” by Lawrence T. Lamont, Jr.

Gordon E. Osterstrom

J. Vac. Sci. Technol. 10, 895 (1973); http://dx.doi.org/10.1116/1.1318450 (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
81.15.Cd Deposition by sputtering
07.30.Cy Vacuum pumps

Reply to Comments by G. E. Osterstrom Regarding “Some Special Pumping Problems Associated With the Sputtering Application”

Lawrence T. Lamont

J. Vac. Sci. Technol. 10, 896 (1973); http://dx.doi.org/10.1116/1.1318451 (1 page)

Full Text: | Download PDF

Abstract Unavailable
Show PACS
81.15.Cd Deposition by sputtering
07.30.Cy Vacuum pumps
Close

© 2012 AVS Science & Technology of Materials, Interfaces, and Processing Help | Contact
close