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1 Jun 1986

Volume 59, Issue 11, pp. 3621-3933

Page 2 of 3 Pages Previous Page Next Page | Jump to Page

Degradation of the electrical characteristics of the Si–SiO2 interface induced by electron injection

C. Falcony and F. H. Salas

J. Appl. Phys. 59, 3787 (1986); http://dx.doi.org/10.1063/1.336767 (5 pages) | Cited 5 times

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The effects of electron injection on the electrical characteristics of the Si–SiO2 interface have been studied on metal‐oxide‐semiconductor type structures incorporating very thin oxide films (≲200 Å). Electron current across the oxide is obtained by Fowler–Nordheim tunneling in Al:SiO2:Si structures or by enhanced Fowler–Nordheim tunneling in Al:Si‐rich‐SiO2:SiO2:Si devices. The changes induced by charge injection in these structures were monitored by measuring the 1‐MHz and the quasistatic capacitance versus voltage characteristic curves. In both structures negative charge trapping in the oxide and positive charge accumulation were observed as well as generation of interface states at approximately 0.6 eV from the top of the Si valence band. However, in structures with Si‐rich‐SiO2 layers an anomalous peak in the quasistatic capacitance curves was observed to be induced by the injection of electrons. The role of the Si‐rich‐SiO2 layer in these phenomena is discussed.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
81.40.Rs Electrical and magnetic properties related to treatment conditions

Current–voltage characteristics through GaAs/AlGaAs/GaAs heterobarriers grown by metalorganic chemical vapor deposition

I. Hase, H. Kawai, K. Kaneko, and N. Watanabe

J. Appl. Phys. 59, 3792 (1986); http://dx.doi.org/10.1063/1.336768 (6 pages) | Cited 45 times

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Current–voltage characteristics of GaAs/AlxGa1−xAs /GaAs heterobarriers grown by metalorganic chemical vapor deposition were investigated for x from 0.32 to 0.46. Calculation of the current, which included just two components—a tunneling component and a thermionic component—agreed well with experimental results. The tunneling effective mass used is the same as the Γ point effective mass when x is 0.32; this value allows the calculated results to fit the experimental data. The tunneling effective mass becomes much larger than the Γ point mass as x increases. This fact suggests that the other band edge X participates in the tunneling process, making the effective mass larger as it approaches the Γ point edge. The barrier heights deduced from I–V and I–T relations are in good agreement. The results support a ratio of 60%–65% of AlGaAs/GaAs conduction‐band discontinuity to the total band‐gap difference.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Cw Elemental semiconductors
73.61.Ey III-V semiconductors
73.61.Ga II-VI semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
73.40.Ty Semiconductor-insulator-semiconductor structures
73.40.Gk Tunneling

Calculation of warm electron transport in AlGaAs/GaAs single heterostructures using a Monte Carlo method

Kiyoyuki Yokoyama and Karl Hess

J. Appl. Phys. 59, 3798 (1986); http://dx.doi.org/10.1063/1.336769 (5 pages) | Cited 19 times

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A simulation of electronic transport in AlGaAs/GaAs single‐well structures including multisubband conduction has been performed based upon an ensemble Monte Carlo method. During the transient calculation, the electronic states of the quantum well are calculated in a fully self‐consistent manner by including the influence of the changes in the energy distribution on the quantum well potential. The numerically obtained wave functions and energy levels are also used to update the major scattering matrix elements. The increase in electron energy with time and the corresponding changes of matrix elements and self‐consistent field (through dependence of screening on the electron energy distribution) lead to a decrease in both velocity overshoot effects and steady‐state drift velocity in low electrical fields at a low lattice temperature.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Transitional behavior of pulsed dc losses in superconducting solenoids with self‐fields greater than B∗

J. Thomas Broach, W. David Lee, and Russell Eaton

J. Appl. Phys. 59, 3803 (1986); http://dx.doi.org/10.1063/1.336770 (4 pages) | Cited 2 times

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Losses were calorimetrically measured for five multilayer superconducting solenoids carrying pulsed dc transport currents. The solenoids, which were wound from commercial NbTi multifilamentary wire, had self‐fields of B∗<B<15 B∗, where B∗ is the calculated field for full penetration of the filament. Loss measurements were taken as a function of peak current at a fixed frequency of 10 Hz and as a function of frequency (1–10 Hz) at a peak current of 30 A. The data do not agree with existing full or partial penetration loss models. The range of magnetic fields between the dominance of either full or partial penetration was found to be wider than expected. A model proposed by Ashkin predicted such a region and his technique for loss calculation agrees with the data.
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85.25.-j Superconducting devices
74.70.-b Superconducting materials other than cuprates
84.32.Hh Inductors and coils; wiring

Optical detector using superconducting BaPb0.7Bi0.3O3 thin films

Youichi Enomoto and Toshiaki Murakami

J. Appl. Phys. 59, 3807 (1986); http://dx.doi.org/10.1063/1.336720 (8 pages) | Cited 57 times

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This paper describes a highly sensitive optical detector using a perovskite‐type superconductor, BaPb0.7Bi0.3O3 (BPB) thin film. Optical signals create quasiparticles and induce changes in the superconducting energy gap. These changes are measured by tunnel junctions which are formed along the grain boundaries in the BPB polycrystalline thin film. The detector sensitivity is about 104 V/W in the 1–8‐μm wavelength range, and the detector is found to be capable of responding up to 1.3 GHz at the 1.3‐μm wavelength. Consequently, this BPB detector is well suited in infrared spectrometer and optical‐communications system applications.
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74.50.+r Tunneling phenomena; Josephson effects
85.60.Gz Photodetectors (including infrared and CCD detectors)
85.25.-j Superconducting devices
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Mathematical model for the calculation of magnetization in anisotropic materials

Edward P. Furlani and Alan G. Baker

J. Appl. Phys. 59, 3815 (1986); http://dx.doi.org/10.1063/1.336721 (5 pages)

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A three‐dimensional formalism has been developed that can be used to compute the anhysteretic magnetization of anisotropic materials. The formalism represents a statistically based mean‐field model in which the material is characterized as an ensemble of pseudodomains. The magnetization of the ensemble is obtained using a Maxwell–Boltzmann distribution with an energy dependence that includes both interactive and anisotropic terms. The model is applied to a single crystal of cobalt and excellent agreement with experimental data is obtained.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Cr Saturation moments and magnetic susceptibilities
75.60.Ch Domain walls and domain structure

Magneto‐optical properties of substituted cobalt ferrites: CoFe2−xMexO4 (Me=Rh3+, Mn3+, Ti4++Co2+)

J. W. D. Martens

J. Appl. Phys. 59, 3820 (1986); http://dx.doi.org/10.1063/1.336722 (4 pages) | Cited 13 times

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The Faraday rotation has been calculated at 1.55‐eV photon energy (800 nm wavelength) for various substitutions in CoFe2O4 from the optical constants and the Kerr rotation and ellipticity spectra of polycrystalline bulk samples. The Faraday rotation consists of contributions both from the Co2+→Fe3+ charge transfer transition on octahedral sites as well as from the Co2+ 4A2→4T1 (P) crystal‐field transition on tetrahedral sites, both centered around 2‐eV photon energy. For the various substitutions the contribution of the crystal field transition to the Faraday rotation at 1.55 eV is determined by the amount of Co2+ on tetrahedral sites as well as the shift in energy of this transition upon substitution. A significant contribution of the 4A2→4T1 (P) transition to the Faraday rotation at 1.55 eV is reached in Rh3+ substituted CoFe2O4.
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78.20.Ls Magneto-optical effects

Magnetic anisotropy of MnAl and MnAlC permanent magnet materials

L. Pareti, F. Bolzoni, F. Leccabue, and A. E. Ermakov

J. Appl. Phys. 59, 3824 (1986); http://dx.doi.org/10.1063/1.336723 (5 pages) | Cited 7 times

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The magnetocrystalline anisotropy of MnAl and MnAlC alloys, in the range of existence of the ferromagnetic τ phase, has been studied by using the singular point detection technique. The anisotropy field value at 293 K varies from 39 kOe for low manganese and high carbon content to 55 kOe for high manganese and carbon‐free samples. The anisotropy of the MnAl τ phase is well described by using only the K1 anisotropy constant. The temperature dependence of the calculated anisotropy constant indicates that a single ion mechanism is the origin of the magnetocrystalline anisotropy in these alloys.
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75.30.Gw Magnetic anisotropy
75.50.Cc Other ferromagnetic metals and alloys
07.55.Db Generation of magnetic fields; magnets
85.70.-w Magnetic devices

Study of the α and β relaxations on a commercial poly(vinyl chloride) by thermally stimulated creep and depolarization current techniques

J. J. del Val, A. Alegría, J. Colmenero, and C. Lacabanne

J. Appl. Phys. 59, 3829 (1986); http://dx.doi.org/10.1063/1.336724 (6 pages) | Cited 33 times

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Thermally stimulated creep and depolarization current measurements have been carried out in a temperature range between −180 and 120 °C, on a pure commercial poly(vinyl chloride). Mechanical and dielectric relaxation times involved in α and β relaxations are obtained by fractional stresses/polarizations procedure. The distribution of the Arrhenius‐like kinetic parameters, deduced from the relaxation times, is interpreted in terms of compensation laws. From the obtained results, a same molecular origin can be assumed for the mechanical and dielectric behavior in both α and β relaxations. Moreover, the compensation law analysis leads to two different relaxations modes, likely associated to two kinds of thermally activated molecular motions, in β relaxation. In the α region, the values of found kinetic parameters point out a high degree of cooperativeness of the involved molecular motions. Depolarization curve in this region shows a high temperature peak, not found in the mechanical one, whose evolution with the poling field allows us to assign it to a nondipolar process associated to the movement of free charge carriers.
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62.20.Hg Creep
77.22.Gm Dielectric loss and relaxation
61.41.+e Polymers, elastomers, and plastics

Band discontinuities and calculations of GaAs‐AlGaAs superlattice structures

A. Chomette, B. Deveaud, M. Baudet, P. Auvray, and A. Regreny

J. Appl. Phys. 59, 3835 (1986); http://dx.doi.org/10.1063/1.337039 (6 pages) | Cited 15 times

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The first two optical transition energies of GaAs‐Ga(Al)As superlattices and multiquantum wells with small well widths are quite sensitive to the band discontinuity. On a series of samples the parameters of which are determined by x‐ray diffraction, we compare the energies measured in photoluminescence and photoluminescence excitation spectroscopies with the results of calculations within the framework of the envelope function approach and with the simple Kronig–Penney model. The envelope function approximation models give transition energies systematically smaller than the experimental values and the discrepancy increases when the well width decreases. With the Kronig–Penney model, both excitonic transitions are satisfactorily calculated for each sample with a conduction‐band offset around 75%, but we do not find a unique value of the conduction‐band offset for all samples.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
78.40.Fy Semiconductors
71.23.An Theories and models; localized states
71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds

Photoluminescence study of residual shallow acceptors in liquid‐encapsulated Czochralski‐grown InP

Eishi Kubota, Akinori Katsui, and Kiyomasa Sugii

J. Appl. Phys. 59, 3841 (1986); http://dx.doi.org/10.1063/1.336725 (6 pages) | Cited 8 times

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For nominally undoped InP crystals grown in silica, pBN, ceramic AlN, and pG crucibles by the liquid‐encapsulated Czochralski (LEC) technique, residual shallow acceptors are investigated by photoluminescence measurements. Mg and Ca, contained in the InP starting materials, are found to be removed due to reactions with the B2O3 encapsulant. Zn and C, of which Zn was dominant throughout the undoped crystals, are found to be residual acceptors incorporated during LEC growth. The B2O3 encapsulant is identified as one Zn contamination source.
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78.40.Fy Semiconductors
61.72.S- Impurities in crystals
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
81.10.Fq Growth from melts; zone melting and refining

Optical reflectance in GaAs/AlGaAs quantum wells

P. J. Pearah, J. Klem, T. Henderson, C. K. Peng, H. Morkoç, D. C. Reynolds, and C. W. Litton

J. Appl. Phys. 59, 3847 (1986); http://dx.doi.org/10.1063/1.336726 (4 pages) | Cited 5 times

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Molecular‐beam epitaxial GaAs/AlGaAs bulk layers and quantum well heterostructures have been grown and characterized at 3 K using broadband optical reflectance and photoluminescence spectroscopy. Reflectance spectra display sharp, well‐defined features due to strong near‐band gap excitonic effects that cause the reflectance to deviate by over 50% from the bulk value in some cases. Features due to impurity‐bound excitons, free‐to‐bound transitions, and free excitons have all been identified in quantum well heterostructures. Interband transitions involving the n=1 light hole and higher‐lying subbands are much more readily observed in reflectance spectra than in photoluminescence, including ‘‘forbidden’’ Δn≠0 transitions. Additionally, reflectance has been used to probe the interfaces, revealing fine structure due to monolayer and submonolayer deviations in well thickness.
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75.20.Ck Nonmetals
68.55.-a Thin film structure and morphology
78.40.Fy Semiconductors

Electron field emission from intentionally introduced particles on extended niobium surfaces

R. J. Noer, Ph. Niedermann, N. Sankarraman, and Ø. Fischer

J. Appl. Phys. 59, 3851 (1986); http://dx.doi.org/10.1063/1.336727 (10 pages) | Cited 12 times

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Field emission properties of microscopic particles of graphite, sulfur, and MoS2 deposited on nonemitting Nb surfaces under ultrahigh vacuum conditions are described. Both graphite and MoS2 particles are shown to emit strongly, with field enhancement factors of the order of 100, in contrast to sulfur particles, which emit only weakly. The emission characteristics are measured locally on the individual sites, and emitting particles are further characterized by microfocus Auger spectroscopy and scanning electron microscopy. Their behavior upon heat treatment was studied, with the main result that both for graphite and MoS2 particles the emission disappears after heating to 1200 °C. The properties of the artificially created emitters are compared with those of naturally occurring field emitters.
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79.70.+q Field emission, ionization, evaporation, and desorption
81.40.Gh Other heat and thermomechanical treatments
52.80.Vp Discharge in vacuum

Excimer laser etching of polymers

V. Srinivasan, Mark A. Smrtic, and S. V. Babu

J. Appl. Phys. 59, 3861 (1986); http://dx.doi.org/10.1063/1.336728 (7 pages) | Cited 91 times

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The ablative decomposition of polyimide, poly(methylmethacrylate), and TNS2 photoresist at high excimer laser (ArF and KrF) fluences (>1 J/cm2) is investigated. It is found that the mechanism of etching is both photochemical and thermal in nature at these fluences. A model, in which a thermal contribution to etching is added to the photochemical contribution derived from low fluence measurements, has been found to represent the experimental data satisfactorily. It is also shown that feature sizes as small as 0.4 μm can be delineated on polymeric materials in a self‐developing manner using 193‐nm laser pulses and contact‐printing techniques.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.65.-b Surface treatments
82.50.-m Photochemistry
79.20.Ds Laser-beam impact phenomena

Electron flow and impedance of an 18‐blade frustum diode

T. W. L. Sanford, J. R. Lee, J. A. Halbleib, J. P. Quintenz, R. S. Coats, W. A. Stygar, R. E. Clark, D. L. Faucett, D. Webb, C. E. Heath, P. W. Spence, J. Kishi, L. G. Schlitt, and D. Morton

J. Appl. Phys. 59, 3868 (1986); http://dx.doi.org/10.1063/1.336729 (13 pages) | Cited 1 time

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A new, large‐area, high‐uniformity, flash x‐ray source that efficiently couples electrical energy to photon energy has been successfully constructed and tested on the 1‐MV, 2‐MA electron accelerator SPEED (short pulse experimental electron device). The source employs 18 individual blade diodes arranged in the configuration of a frustum. Each blade was magnetically isolated on the real‐cathode side of an anode foil, but not on the virtual‐cathode side. The operation of the diode was heavily diagnosed using 24 Rogowski coils, a vacuum voltage monitor, p‐i‐n diode detectors, an 80‐element TLD array, and a fast‐framing x‐ray pinhole carnera. The individual blade diodes were found to exhibit line pinching, end‐to‐end pinching, and minimal electron reflexing through the Ta anode foil, with a radiation yield that agreed with Monte Carlo simulations. The end‐to‐end pinch location could be controlled by tapering the anode–cathode gap. The impedance depended on only the smallest spacing, and was independent of pinch location.
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84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
41.75.Fr Electron and positron beams
07.85.-m X- and γ-ray instruments
28.41.Te Protection systems, safety, radiation monitoring, accidents, and dismantling

High‐field tunneling calculations in metal‐oxide‐silicon capacitors incorporating the perimeter effect

Terence B. Hook and T.‐P. Ma

J. Appl. Phys. 59, 3881 (1986); http://dx.doi.org/10.1063/1.336730 (9 pages) | Cited 4 times

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The potential distribution is calculated for a generalized metal‐oxide‐silicon capacitor using the Schwartz–Christoffel transformation. The results are used to calculate the high‐field tunneling current in such a device, with particular attention to the field enhancement effect of the edge of the gate electrode. It is found that the total current through even a large‐scale device can be dominated by the perimeter component. The dependence of the field enhancement on several device parameters is examined theoretically. In particular, thick oxides and thin, steep gate electrodes augment the field enhancement.
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73.40.Gk Tunneling
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
84.32.Tt Capacitors

A model for conductor failure considering diffusion concurrently with electromigration resulting in a current exponent of 2

M. Shatzkes and J. R. Lloyd

J. Appl. Phys. 59, 3890 (1986); http://dx.doi.org/10.1063/1.336731 (4 pages) | Cited 111 times

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A model was constructed for electromigration failure where both Fickian diffusion and mass transport due to the electromigration driving force are considered concurrently. The solution to the resulting diffusion equation yields a current exponent of 2 and an activation energy consistent with grain‐boundary self‐diffusion. A modification of the standard median time to failure equation first proposed by Black is suggested.
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66.30.Qa Electromigration
85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)
66.30.Fq Self-diffusion in metals, semimetals, and alloys

Electrical properties of Schottky diodes of Ti on highly doped GaAs

A. Zussman

J. Appl. Phys. 59, 3894 (1986); http://dx.doi.org/10.1063/1.336732 (7 pages) | Cited 7 times

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I‐V and C‐V characteristics of Schottky diodes prepared by Au/Pt/Ti evaporation and by Ti sputtering on GaAs substrates with electron concentrations of 1.5×1017, 4.5×1017, and 3.5×1018 cm−3 were measured as a function of temperature between 77 and 300 K. The ideality factor was found to follow the theory of thermionic field emission. Closer agreement with that theory was observed for evaporated and annealed diodes and for sputtered diodes than for evaporated, as‐deposited devices. The sputtered diodes exhibited the best I‐V characteristics with an ideality factor n=1.04 and a reverse current lower by more than two orders of magnitude than that of the evaporated devices at 300 K. This behavior was attributed to the presence of an interfacial oxide layer in the evaporated devices. Departure from the thermionic field emission theory was observed in devices with Nd≥4.5×1017 cm−3 at low forward bias and was attributed to current transport due to a mechanism of multistep recombination tunneling through defects.
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85.30.Hi Surface barrier, boundary, and point contact devices
73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Ns Metal-nonmetal contacts
79.90.+b Other topics in electron and ion emission by liquids and solids and impact phenomena (restricted to new topics in section 79)

Modified image method: Application to the response of layered ohmic conductors to active electromagnetic sources

Clyde J. Bergeron

J. Appl. Phys. 59, 3901 (1986); http://dx.doi.org/10.1063/1.336733 (8 pages) | Cited 6 times

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The standard image method is modified in order to extend its range of applicability to the near‐space regime (h∼λ the screening length) for all electromagnetic screening phenomena in conducting matter which are governed by Helmholtz’s equation. The modified method assumes a single image of a near inducing source and that the effective location of the image plane and surface screening distribution that satisfy the electromagnetic boundary conditions is one screening length below the free surface of the conductor. For applications in which the primary source and detector distance from the conducting free surface is much greater than the appropriate screening length, the modified image method (MIM) reduces to the standard form. An additional ad hoc modification for the case of induced ohmic screening is introduced into Wait’s multilayer correction function Q which is used in the definition of the complex screening length for the MIM model. This results in an extended range of agreement (both as to amplitude and phase )between the complex image fields produced by the MIM model and the secondary field produced by induced currents in the layered conducting half‐space as originally formulated by Sommerfeld. This suggests the use of MIM, at least as a first‐order tool, for rapid real‐time inverse calculations of the structure parameters, conductivities, and thickness of the layers. The good agreement between MIM and the standard theory for a two‐layer model occurs over a range of values for the parameters that define the conducting structure and the geometry of the source and sensor coils which are relevant to airborne active electromagnetic source (AEM) coastal bathymetry, sea ice thickness measurements, and studies of salt water intrusions of river deltas and marshes. The success of this application of the MIM model in the near‐field regime for ohmic screening suggests the applicability of MIM in calculating the near‐field electrostatic and superconducting response of conducting matter as well.
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41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
93.85.-q Instruments and techniques for geophysical research: Exploration geophysics
92.10.Sx Coastal, estuarine, and near shore processes

Molecular‐beam epitaxy of GaSb/AlSb optical device layers on Si(100)

R. J. Malik, J. P. van der Ziel, B. F. Levine, C. G. Bethea, and J. Walker

J. Appl. Phys. 59, 3909 (1986); http://dx.doi.org/10.1063/1.336734 (3 pages) | Cited 13 times

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We report for the first time the growth of GaSb/AlSb multilayers and alloys on Si(100) by molecular‐beam epitaxy. High‐quality films were achieved in spite of the large lattice constant mismatch of 12%. Room temperature, optically pumped pulsed lasers emitting at 1.8 μm have been demonstrated. Lateral photoconductive detectors with responsivities of 0.18 A/W have also been made. The film nucleation on the Si substrate was observed in situ by reflection high‐energy electron diffraction. Characterization of the grown epilayers and preliminary optical device results are described.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
42.55.Px Semiconductor lasers; laser diodes
85.60.Gz Photodetectors (including infrared and CCD detectors)
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Electric field‐induced negative photoconductivity in GaAs

H. H. Wieder, Cynthia M. Hanson, and Rainer Zuleeg

J. Appl. Phys. 59, 3911 (1986); http://dx.doi.org/10.1063/1.336735 (3 pages) | Cited 5 times

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High‐field negative photoconductivity observed below the fundamental band gap of GaAs is attributed to the electric field‐dependent capture cross section of an electron donor level located at 1.2 eV relative to the valence‐band edge and to a dynamic balance between emission, trapping, and recombination of optically induced charge carriers.
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72.40.+w Photoconduction and photovoltaic effects
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.40.Fy Semiconductors
72.20.Ht High-field and nonlinear effects

Deposition of refractory metal films by rare‐gas halide laser photodissociation of metal carbonyls

Diane K. Flynn, Jeffrey I. Steinfeld, and Dhanwant S. Sethi

J. Appl. Phys. 59, 3914 (1986); http://dx.doi.org/10.1063/1.336736 (4 pages) | Cited 35 times

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Films of Cr, Mo, and W on quartz, Pyrex, Suprasil, and Al substrates were deposited by photodissociation of the respective hexacarbonyls using focused and pulsed radiation from rare‐gas halide lasers. Cr was deposited by dissociation of Cr(CO)6 using XeF (308 nm), KrF (249 nm), and ArF (193 nm) lasers. Mo and W were deposited from their respective hexacarbonyls at 249 and 193 nm. Pulse energies varied between 8 and 12 mJ. Pulse rates of 10–60 Hz were used. The pulse duration was about 10 ns. Depositions with substrates both parallel and perpendicular to the excimer radiation were attempted. Only in the case of perpendicular configuration were strongly adherent films observed. The deposition rates for thicknesses up to 3000 Å appeared to be independent of the pulse rate for all three metals. The films exhibited strong adhesion to the substrate. Scanning electron microscope photographs of the films revealed the presence of continuous metal layers. Auger and x‐ray analyses of the films indicated contamination from carbon and oxygen. The source of these impurities is most likely to be CO produced in the decarbonylation of the parent hexacarbonyl. Adhesion to the substrate is apparently enhanced by laser stimulated generation of strong binding sites on the surface.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
82.50.-m Photochemistry

Distributed amplifier using Josephson vortex flow transistors

D. P. McGinnis, J. B. Beyer, and J. E. Nordman

J. Appl. Phys. 59, 3917 (1986); http://dx.doi.org/10.1063/1.336737 (3 pages) | Cited 8 times

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A wide‐band traveling wave amplifier using vortex flow transistors is proposed. A vortex flow transistor is a long Josephson junction used as a current controlled voltage source. The dual nature of this device to the field effect transistor is exploited. A circuit model of this device is proposed and a distributed amplifier utilizing 50 vortex flow transistors is predicted to have useful gain to 100 GHz.
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84.30.Le Amplifiers
85.25.-j Superconducting devices
85.30.Tv Field effect devices
74.50.+r Tunneling phenomena; Josephson effects

Growth of crystalline zinc sulfide films on a (111)‐oriented silicon by molecular‐beam epitaxy

Meiso Yokoyama and Shin‐ichi Ohta

J. Appl. Phys. 59, 3919 (1986); http://dx.doi.org/10.1063/1.336738 (3 pages) | Cited 9 times

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The molecular‐beam epitaxial growth of undoped ZnS layers on Si (111) is reported. Reflection high energy electron diffraction observations of grown films indicated that the optimum growth conditions necessary to obtain good crystallographic quality ZnS films exhibiting surface reconstruction are a substrate temperature of 300 °C and a molecular‐beam flux ratio of 1. The layer growth rate depends on both substrate temperature and the molecular‐beam flux ratio of Zn to S, JZn/JS. It was found that the growth rate became constant for JZn/JS ratios larger than 1. For the substrate temperatures larger than 400 °C the growth rate was found to decrease to nearly zero, abruptly.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.-a Thin film structure and morphology

Formation of thin silicon oxide films by rapid thermal heating

J. P. Ponpon, J. J. Grob, A. Grob, and R. Stuck

J. Appl. Phys. 59, 3921 (1986); http://dx.doi.org/10.1063/1.337040 (3 pages) | Cited 18 times

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Rapid thermal heating of silicon samples in a dry O2 ambient has been used to form thin SiO2 films. Compared to conventional furnace oxidation, an increased growth rate was observed which is linearly dependent on the square root of time. Activation energies of 1.99 and 2.26 eV for 〈111〉 and 〈100〉 orientation, respectively, have been determined in the range 1000–1200 °C.
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81.65.-b Surface treatments
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.-a Thin film structure and morphology
81.40.Gh Other heat and thermomechanical treatments
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