bluuebunny/crossref_metadata_2025 huggingface dataset:
Submillimeter-laser-induced air breakdown
Authors: Woskoboinikow P. , Mulligan W. J. , Praddaude H. C. , Cohn D. R.
Published: February 2003

We report the first demonstration of laser-induced air breakdown at submillimeter wavelengths. An optically pumped D2O oscillator-amplifier laser system which produced 75-ns pulses at the megawatt level on the 385- and 359-μm transitions was used. Focusing the 10-cm-diam laser beam with a 20- or 38-cm-focal-length mirror onto an arbitrary surface to produce initial ionization caused multiple air breakdown plasmas with a threshold on the order of 1 MW cm−2. Theoretical (ω2+ν2)/ν scaling from the ruby and the neodymium laser air breakdown thresholds, where ω is the laser angular frequency and ν is the electron-molecule collision frequency, is in agreement with this initial experimental result.
Quenching of photoconductivity in silver sulfide thin layers by ultraviolet radiation
Authors: Mardix S. , Chi M.
Published: February 2003

Photoconductivity in certain thin layers of silver sulfide was found to be quenched at room temperature by a secondary exposure to ultraviolet. The photocurrent induced by the primary radiation of wavelengths longer than 600 nm is linearly dependent on the light intensity. The quenched part of the photocurrent I− was found to depend on both the primary intensity L+ and the secondary intensity L−: 1/I−=A/L++B/L−+C, where A, B, and C are constants. The possibility is mentioned that the reported effect is associated with a photographic effect induced by the ultraviolet radiation.
Light emission from gold particles excited by electron tunneling
Authors: Hansma P. K. , Broida H. P.
Published: February 2003

After gold particles are deposited onto an oxidized aluminum strip by the evaporation of gold in argon, tunnel junctions can be formed by making contact to the particles with a thin gold film. Red polarized light is emitted from these junctions when a few volts of potential difference is applied. Such junctions can be operated and stored at room temperature for several weeks.
Thin-film gallium arsenide solar cells on tungsten/graphite substrates
Authors: Chu Shirley S. , Chu T. L. , Yang H. T.
Published: February 2003

Polycrystalling gallium arsenide films deposited on tungsten/graphite substrates by the reaction of gallium, hydrogen chloride, and arsine have been used for the fabrication of MOS-type solar cells. The deposited films were oxidized in situ with an argon-oxygen mixture and, in some cases, followed by a water-vapor treatment. Gold was used as the barrier metal, and titanium oxide was used as the antireflection coating. Large-area (6–9 cm2) solar cells with an AM1 efficiency of about 5.5% have been produced.
Long-pulse ultraviolet laser emission in an electron-beam-excited supersonic flow
Authors: Forestier B. , Fontaine B.
Published: February 2003

Long-pulse laser action has been achieved at several wavelengths near 350 nm in an electron-beam-excited supersonic flow. Laser emission on XeF has been obtained when Ne/Xe/NF3 mixtures aerodynamically cooled to 120 K and at a pressure of 0.45 atm were excited by an electron beam of medium intensity. About 1 mJ of laser energy was obtained in a 400-ns FWHM pulse, limited only by the electron-beam pulse length. Lasing was also achieved on two ultraviolet lines in Ne/NF3 mixtures cooled down to 80 K.
Direct measurement of the partial waves of a surface acoustic wave by means of light scattering
Authors: Sarid Dror , Stegeman George I.
Published: February 2003

We report the direct measurement of each of the partial waves which constitute a surface acoustic wave propagating on a y-z LiNbO3 crystal by means of light scattering on internal reflection. It is shown both theoretically an experimentally that each of the partial waves has a wave vector pointing in a different direction. We could account theoretically for the shape of the scattered light which is split into several components. Each component corresponds to a single partial wave.
A new technique for excitation of surface and shear acoustic waves on nonpiezoelectric materials
Authors: Khuri-Yakub Butrus T. , Kino G. S.
Published: February 2003

An interdigital transducer deposited on a piezoelectric substrate has been used to excite SAW on nonpiezoelectric materials by using a fluid couplant. The piezoelectric substrate is held at an angle to the nonpiezoelectric material so as to match the tangential k vectors of the surface waves. Experiments have been carried out with a LiNbO3 piezoelectric substrate and a ceramic such as SiC or Si3N4 with a fluid couplant. At a center frequency of 100 MHz, the estimated conversion efficiency of the surface wave from the piezoelectric to the nonpiezoelectric material is −3.5 dB. The results compare favorably with a normal mode coupling theory we have developed which predicts −2.7 dB efficiency.
Acoustic memory correlator using GaAs Schottky diodes
Authors: Gautier H. , Maerfeld C. , Tournois P.
Published: February 2003

A memory correlator using a matrix of Pt-GaAs Schottky diodes airgap coupled to a LiNbO3 substrate has been built. The high barrier potential of this type of junction (900 mV) leads to low diode leakage currents. As a consequence, storage time constants of up to 0.4 s have been measured at room temperature, while charging times can be as short as 10 ns. The other device characteristics are detailed, and particularly the possibility of correlating signals of several millisecond duration.
Schottky barrier diodes for low noise mixing in the far infrared
Authors: Kelly William M. , Wrixon Gerard T.
Published: February 2003

Contributions from semiconductor plasma resonance and skin effect to the series resistance of Schottky barrier diodes are incorporated in a calculation of conversion loss for the submillimeter region. The calculation includes both intrinsic and parasitic losses and shows the conversion loss to be strongly dependent upon frequency of operation and upon diode diameter. At higher frequencies mixer performance may be optimized by careful choice of epitaxial carrier concentration and of diode size.
Application of Li2O compensation techniques to Ti-diffused LiNbO3 planar and channel waveguides
Authors: Burns W. K. , Bulmer C. H. , West E. J.
Published: February 2003

We report a novel technique to determine the index change in Li2O in-diffused surface layer in LiNbO3 by observing the cutoff angle of the extraordinary substrated mode as it refracts through the surface-layer–substrate interface. Surface-layer index changes from 10−4 to 10−2 were measured in various samples which received compensation treatments for times of 10 min to 6 h, primarily in LiNbO3 powder. We also report the successful compensation of nearly single-mode Ti : LiNbO3 channel waveguides.
Oxidation mechanisms in WSi2 thin films
Authors: Zirinsky S. , Hammer W. , d’Heurle F. , Baglin J.
Published: February 2003

The utilization of WSi2 thin films as gate electrodes in field-effect transistors depends on the ability of this material to form a continuous electrically insulating SiO2 overlayer. In the steam oxidation of WSi2 films deposited on polysilicon, SiO2 forms on the surface by means of the rapid diffusion of Si through the WSi2 which appears in this case to be quite inert. During the initial stages of the steam oxidation of WSi2 films deposited on SiO2, removal of Si from the silicide (to form SiO2) apparently leads to the formation of free W, rather than the anticipated tungsten-rich W3Si3.
Identification of diffusion species in V-SiO2 reactions
Authors: Chu W.K. , Tu K. N.
Published: February 2003

Interfacial reactions between vanadium and thermally grown SiO2 films have been studied with Xe ions implanted in the SiO2 as diffusion markers. After the sample is heated at temperatures from 700 to 900 °C, the SiO2 decomposes and V3Si forms. A backscattering analysis of the marker displacement discloses that vanadium is the dominant moving species which diffuses through the V3Si to react with the SiO2, whereas the oxygen atoms generated as a result of the reaction outdiffuse and oxidize the outer vanadium layer. For a clear presentation of the reaction and marker motion, the usual energy spectra of backscattering have been converted to in-depth compositional profiles.
New method of GaAs passivation with thin polymer films
Authors: Brosset D. , Ai Bui , Segui Y.
Published: February 2003

MIS capacitors have been developed on a GaAs (n) substrate, the insulation being a thin layer of polymethylsiloxane (a few thousand angstroms thick). The present aim is to find out whether this process can provide an answer for the passivation of compound-semiconductor components. The thin layer is deposited on the gallium arsenide substrate. It is obtained by glow discharge in a hexamethyldisiloxane vapor at ambient temperature. The C-V curves enable the polymer-semiconductor interface properties to be determined, and in particular the calculation of fixed charges contained in the polymer (QT) and the surface-state density (Nss).
Thermal switching times of superconducting proximity effect weak links
Authors: Franson J. D. , Mitchard G. S. , Mercereau J. E.
Published: February 2003

At sufficiently low temperatures the onset of thermal hysteresis allows proximity effect weak links to be switched between two stable states. The time required for the voltage to switch between these two states was experimentally measured and found to lie in the range 200–500 psec. The measurements showed detailed agreement with calculations based on a simple heating model.
Detection of atomic hydrogen and deuterium by resonant three-photon ionization
Authors: Bjorklund G. C. , Ausschnitt C. P. , Freeman R. R. , Storz R. H.
Published: February 2003

Resonantly enhanced three-photon ionization spectroscopy is employed for the detection of ground-state atomic hydrogen and deuterium. Concentrations as low as 4×109 atoms/cm3 in the presence of 1017 atoms/cm3 of buffer gas are detected with an implicit time resolution of less than 10 nsec. A useful dynamic range of at least 4×104 is demonstrated and saturation of the ionization in a 2×10−4-cm3 focal volume is observed. The presence of H can easily be distinguished from that of D and the three-dimensional spatial distribution of H or D can be determined.
Laser annealing of diffusion-induced imperfections in silicon
Authors: Young R. T. , Narayan J.
Published: February 2003

High-temperature diffusion of boron or phosphorus into silicon leads to the formation of spherical precipitates and/or dislocation loops in the diffused layer which influence electrical junction characteristics. These diffusion-induced imperfections can be removed by high-energy pulse laser treatment. The boron or phosphorus atoms previously contained in the precipitates become electrically active and the resulting dopant concentration can exceed the solid solubility limit.
Superconducting properties of i
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u prepared Nb-Cu-Sn alloys
Authors: Verhoeven J. D. , Finnemore D. K. , Gibson E. D. , Ostenson J. E. , Goodrich L. F.
Published: February 2003

Alloys of Cu–20 wt% Nb have been prepared by a chill casting technique. After drawing to fine wire, Nb3Sn was formed by plating and diffusion of Sn. The critical-current properties and the resistance to degradation of Jc upon mechanical deformation both compare favorably to commercial Nb3Sn tape.
Hardness and bounding in A15 superconducting compounds
Authors: Chin G. Y. , Wernick J. H. , Geballe T. H. , Mahajan S. , Nakahara S.
Published: February 2003

Microhardness of single crystals of V3Si and V3Ge as well as polycrystalline Nb3Ir, Nb3Au, and Nb3Sn have been measured. The relatively high ratio of hardness to elastic constant C44 supports the existence of strong covalency in A3B compounds of the A15 structure. Correlation with interatomic distance suggests covalent bonding (tight binding) in the A-A chains.
The effect of magnetically aligned powder on the magnetostriction of sintered rare earth–iron Laves phase compounds
Authors: Malekzadeh M. , Pickus M. R.
Published: February 2003

A powder metallurgical approach is utilized to prepare grain-oriented Laves phase compounds of TbxDy1−xFe2. The magnetostrains observed in the oriented compounds, though containing ∼20% porosity as presently prepared, are far superior to those of arc cast and highly dense liquid-phase sintered materials. Also, it is shown that the alignment achieved is strongly dependent on the Tb/Dy ratio.
Organometallic-sourced VPE AlGaAs/GaAs concentrator solar cells having conversion efficiencies of 19%
Authors: Nelson N. J. , Johnson K. K. , Moon R. L. , Vander Plas H. A. , James L. W.
Published: February 2003

AlGaAs/GaAs heterojunction solar cells having conversion efficiencies greater than 19% have been produced on large-area substrates (13 cm2) using the organometallic-sourced VPE process. At 1 sun (simulated AM2) these devices have open-circuit voltages of 1.01 V and short-circuit currents of 20.9 mA/cm2. In sunlight at a flux concentration of 933 suns at AM2.1, a conversion efficiency of 19% and a fill factor of 0.757 was measured.
Theoretical absorption spectra of ArKr
Authors: Bender C. F. , Winter N. W.
Published: February 2003

We present the results of ab initio calculations for the ArKr+ potential-energy curves. The curves and calculated transition moments have been used to calculate the cross section for absorption from the bound ground state. After including spin-orbit interaction, two strong absorptions are predicted with peak cross sections and wavelengths of 1.3×10−16 cm2 at 295 nm and 4.8×10−18 cm2 at 376 nm. The 295-nm absorption band has a cross section of 1.5×10−17 cm2 at the 248-nm wavelength of KrF.
Energy ordering of the excited states of XeF
Authors: Kligler D. , Nakano H. H. , Huestis D. L. , Bischel W. K. , Hill R. M. , Rhodes C. K.
Published: February 2003

Ar/Xe/NF3 mixtures were excited by the focused beam from an ArF (193 nm) laser. Xe+ ions are produced by two-photon ionization, the electrons attach to make F−, and the ions recombine to make XeF*. Radiation is observed in the XeF(B 1/2) →XeF(X 1/2) bands near 351 nm and in the broader XeF(C 3/2) →XeF(A 3/2) band near 460 nm. At low background gas pressure, mostly B-X uv emission is observed. As the argon pressure is increased to 1000 Torr, the visible/uv band intensity ratio increases to about 3 to 1. We conclude from these results that the C (3/2) state lies 700±70 cm−1 below the B (1/2) state. This conclusion should have a significant impact on our understanding of the fluorescence yields and laser performance of e-beam-excited XeF.
A lattice attenuation in CdS measured by the ultrasonic injection method
Authors: Hata Tomonobu , Nakano Takeshi , Koma Kikuo , Hada Toshio
Published: February 2003

This paper concerns the use of Brillouin scattering measurements to study lattice attenuation in semiconducting CdS crystals. Measured acoustic fluxes are produced by the acoustoelectric domains. In order to measure the attenuation constant, an ultrasonic injection method is applied. A sample is divided into two parts; one part is used as a generation region of the acoustic flux [region (1)] and the other part is used as a propagation region of the injected flux [region (2)]. The acoustic attenuations of various frequencies are measured at region (2). The lattice attenuation is greatly affected by the rise time of an applied pulse in region (1). It is clear that acoustic flux in the acoustic domain which originates from the amplification of the pure thermally excited acoustic flux attenuates as f2 and is in accordance with the Akhieser loss. On the other hand, a shock-excited acoustic flux attenuates as f∼1.5.
ZnCl2 glass: A potential ultralow-loss optical fiber material
Authors: Van Uitert L. G. , Wemple S. H.
Published: February 2003

Zinc chloride glass is a potentially useful medium for ultralow-loss (∼1 dB/103 km) optical fibers for wavelengths in the 3.5–4-μm region. In this region, intrinsic absorption, scatter, and material dispersion are all expected to be small, and the common fully oxidized transition metal impurities and H2O should exhibit extremely weak absorption as well.
Loss in cleaved Ti-diffused LiNbO3 waveguides
Authors: Kaminow I. P. , Stulz L. W.
Published: February 2003

The attenuation coefficient and coupling loss were measured in single-mode Ti-diffused LiNbO3 waveguides with cleaved end faces. Coplanar electrodes increase the attenuation substantially but a dielectric buffer layer can eliminate most of the electrode absorption.
The spatial distribution of heating of aluminum targets by laser-ignited air plasmas
Authors: McKay J. A. , Schriempf J. T.
Published: February 2003

Measurements of the heating of metal targets in air by laser pulses with plasma ignition have shown substantial enhancement of thermal coupling compared to simple infrared absorption. This heat is in some cases spread over an area much larger than the laser spot. We present direct measurements of the spatial distribution of aluminum target heating with a high-energy (11 kJ, 40 μs) CO2 laser pulse. This observed distribution is compared to that calculated for a model of thermal coupling via thermal emission from a vertically propagating disk-shaped plasma. This model yields a better fit to the data than is obtained for a model of coupling via thermal conduction from a hydrodynamically expanding plasma due to Robin.
Light-sensitive electron-loss measurements on clean and oxygen-adsorbed amorphous silicon
Authors: Derrien Jacques , Goldstein Bernard , Cros Alain , Salvan Frank
Published: February 2003

We have observed light-sensitive oxygen-induced low-energy electron losses at amorphous silicon surfaces at 7.6, 10.1, and 12.9 eV. The crucial feature of our interpretation is the requirement that surface states in the band gap, isolated from the valence and conduction bands, must be involved in the loss transitions. An energy-level scheme, based on the above requirement and on the valence- and conduction-band structure determined by others, can readily account for the observed loss transitions and their light sensitivity.
Flicker noise in semiconductors: Not a true bulk effect
Authors: van der Ziel A.
Published: February 2003

From the fact that good silicon JFET’s do not have any flicker noise, it is concluded that flicker noise in semiconductors and semiconductor devices cannot be a true bulk effect. Since JFET’s have no semiconductor-oxide interface to speak of, whereas all other semiconductor devices do, this points to the semiconductor-oxide interface as the source of 1/f noise. This leads to the following model. The carriers are trapped and detrapped by oxide traps, and this gives rise to two distinct noise effects: density fluctuation noise that can be described by the McWhorter model and mobility fluctuation noise that could possibly be described by the Kleinpenning model. The two models might therefore ultimately be unified into a single model, and it would depend on the device under study whether one or the other noise effect would predominate.
The influence of laser annealing on lattice damage in single-crystal silicon
Authors: Porter W. A. , Parker D. L. , Richardson T. Wm. , Swenson E. J.
Published: February 2003

The ability of a cw-pumped Nd : YAG laser to anneal process-induced slip damage in silicon is demonstrated via x-ray topography as well as Sirtl etching. Severely dislocated regions of a silicon wafer were scanned by the laser at various power levels. X-ray topographs of the regions indicate that 55–110 J/cm2 can anneal even severely damaged material. Further, the depth of the anneal is estimated to be between 10 and 25 μ.
Determination of surface- and bulk-generation currents in low-leakage silicon MOS structures
Authors: Brotherton S. D. , Gill A.
Published: February 2003

A technique is presented in which, by appropriately biasing a circular MOS capacitor surrounded by an annular electrode, it is possible to directly measure generation currents from controllably depleted surfaces. Knowledge of the surface-generation velocity from this measurement then facilitates the correction of the usual MOS relaxation data to account for generation effects at peripheral surfaces. From the measurements presented, it is demonstrated that the technique is particularly useful for assessing state-of-the-art low-leakage devices.
Frequency up-shift for cyclotron-wave instability on a relativistic electron beam
Authors: Hirshfield J. L. , Chu K. R. , Kainer S.
Published: February 2003

The axial drift of a relativistic electron beam along a uniform magnetic field is shown theoretically to lead to significant frequency up-shifts for linear cyclotron-wave instabilities driven by velocity-space anisotropy. This mechanism suggests novel means for the development of devices for generation of intense far-infrared power.
Electroreflectance of In0.79Ga0.21As0.54P0.46
Authors: Nishino T. , Yamazoe Y. , Hamakawa Y.
Published: February 2003

We have measured Schottky-barrier electroreflectance spectra of an In0.79Ga0.21As0.54P0.46 LPE layer at 81 K. Analysis of the spectra has enabled us to determine the interband reduced mass of the quaternary alloy together with the values of the band gap and spin-orbit splitting. The obtained reduced mass μ=0.033m0, in agreement with the value calculated from interpolations of the accepted values for the related binary compounds.
Ion-implanted InGaAsP avalanche photodiode
Authors: Law H. D. , Tomasetta L. R. , Nakano K.
Published: February 2003

High-quantum-efficiency planar and mesa InGaAsP avalanche photodiodes have been fabricated by beryllium ion implantation. The implanted diodes, after suitable annealing, exhibited a very low dark current density of 4.0×10−6 A/cm2 at 10 V. The devices have 65% external quantum efficiency at 1.06 μm without an antireflection coating and a uniform avalanche gain of 12.
XeF ground-state dynamics in a laser discharge
Authors: Fulghum S. F. , Herman I. P. , Feld M. S. , Javan A.
Published: February 2003

The time evolution of gain and absorption in an XeF laser discharge is studied using a pulsed uv dye-laser probe and timing system with ±7-nsec resolution. The dissociation rate of the lowest vibrational level of the XeF ground state as a function of helium buffer pressure is found to have a slope of 1×104 sec−1 Torr−1 (±15%).
Enhancement of nonlinear optical processes with a double-pass tight-focusing geometry
Authors: Brueck S. R. J. , Kildal Helge
Published: February 2003

The first use of a double-pass geometry to enhance the conversion efficiency of a parametric nonlinear process in the tight-focusing limit is reported. For third-harmonic generation in liquid–CO-O2 mixtures using a CO2 laser pump source, the observed enhancement is 2.5; elimination of reflection losses will result in an enhancement of 4. The double-pass geometry has also been used to obtain accurate measurements of the wave-vector mismatch Δk of the nonlinear medium.
Efficient thallium photodissociation laser
Authors: Ehrlich D. J. , Maya J. , Osgood R. M.
Published: February 2003

We report on an atomic thallium laser at 535.0 and 377.6 nm which is pumped by the photodissociation of TlI with the 193-nm output of an ArF laser. High-resolution Fabry-Perot scans of the 535.0-nm line have shown a structure in the laser spectrum which depends on the Tl inversion density. The energy efficiency for conversion of the pump into thallium laser emission has been measured to be 14±3%.
Ionization coefficients of Ga0.72Al0.28Sb avalanche photodetectors
Authors: Law H. D. , Nakano K. , Tomasetta L. R. , Harris J. S.
Published: February 2003

The performance of an optical receiver depends heavily on the excess multiplication noise characteristics of the avalanche photodetector. The excess multiplication noise factor of an avalanche photodiode depends on the ratio of the electron and hole ionization coefficients. The ionization coefficients of 1.06-μm photodiodes fabricated from Ga0.72Al0.28Sb have been measured. The results show a hole-to-electron ionization-coefficient ratio of 2, which implies an excess gain noise factor F of 5.9 when the diode is operated at a gain of 10.
Mass and energy dependence of the equilibrium surface composition of sputtered tantalum oxide
Authors: Taglauer E. , Heiland W.
Published: February 2003

Anodically oxidized Ta2O5 surfaces were sputtered with 300–1800-eV He+ and Ar+ ions. The surface composition was measured with AES and ISS. The results clearly show that the equilibrium surface composition depends on mass and energy of the primary ions. This composition is reversible for different masses or energies. A short discussion of these effects is given, including the characteristic fluence for obtaining equilibrium.
Lattice deformations and misfit dislocations in GaInAsP/InP double-heterostructure layers
Authors: Oe Kunishige , Shinoda Yukinobu , Sugiyama Koichi
Published: February 2003

Lattice deformations and misfit dislocations are studied by x-ray double-crystal diffraction and topography for GaInAsP/InP double-heterostructure layers epitaxially grown on (001) InP substrates. No misfit dislocation was observed at the interfaces when the misfits Δa⊥/a between the lattice constants normal to the wafer surface of GaInAsP (0.4 μm thick) and InP layers are within about 5×10−3. The unit cell of the GaInAsP epitaxial layer is tetragonally deformed due to the interface lattice misfit such that the lattice constant parallel to the wafer surface is nearly invariant across the GaInAsP/InP interfaces in the DH wafers both with and without misfit dislocations for ‖Δa⊥/a‖<6.4×10−3.
Ohmic contacts produced by laser-annealing Te-implanted GaAs
Authors: Barnes P. A. , Leamy H. J. , Poate J. M. , Ferris S. D. , Williams J. S. , Celler G. K.
Published: February 2003

We report the formation of Ohmic contacts to high-dose (∼1016 cm−2) Te-implanted n-type GaAs annealed with a Q-switched Nd : YAG laser. The annealing results in a Te concentration greater than 10 times the equilibrium solubility and the formation of free Ga at the surface. Ohmic contacts of specific contact resistance rc≃2×10−5 Ω cm2 were obtained by first removing the surface Ga by an HCl etch and then backsputtering to remove 50 Å of GaAs, thereby exposing a surface of high Te concentration.
Compensation of mobile-ion movement in SiO2 by ion implantation
Authors: Topich James A.
Published: February 2003

A study has been undertaken to determine the effect of ion-implanted fluorine on the properties of SiO2 for use as a gate dielectric in MOS devices. C-V measurements and bias-temperature stressing showed that mobile-ion drift can be compensated for by the implanted ions. Further tests showed that it is the implant damage and not the ion itself which was responsible for the compensation. uv excitation of the samples was used in an attempt to identify the nature of the compensation effect, but the results are not definitive.
Axial translation of field-reversing E layers
Authors: Rej D. J. , Tuszewski M. , Davis H. A. , Fleischmann H. H.
Published: February 2003

Experiments are described in which field-reversing E layers were transported axially in RECE-Christa over a distance of up to 10 ring radii using time-varying magnetic fields. When properly executed, this process does not lead to anomalous fast-electron losses. The translation speed appears consistent with that expected from the interaction of the rings with the axial Bz-field gradients and the resistive tank wall. No significant difference is observed between moving the rings in a homogeneous H2 fill and moving them from a transient gas cloud into a low-gas-density region.
Proposed generation of picosecond second-harmonic pulses in Te
Authors: Johnson L. M. , Pratt G. W.
Published: February 2003

The possibility of generating extremely intense picosecond pulses at 5.3 μm by frequency doubling a strong CO2 laser pulse in Te is demonstrated. It is shown that free carriers generated by two-photon absorption at the leading edge of the second harmonic perturb the indices of refraction and greatly reduce the conversion efficiency for the remainder of the pump pulse.
Saturation parameter and small-signal gain of cw CO2 and/or N2O mixing gasdynamic lasers
Authors: Milewski J. , Brunné M. , Polanowski B. , Stańco J. , Volkov A. Yu. , Demin A. I. , Kudriavtsev E. M.
Published: February 2003

The small-signal gain of cw CO2 and/or N2O mixing gasdynamic lasers has been measured by varying the cavity losses with the aid of two rotating coupled NaCl plates placed within the cavity and looking for the generation cutoff point. The saturation parameter has been determined on the basis of measured values of respective small-signal gains by experimentally recovering the output power-cavity losses relation. The measurements yielded α0≃1.1 m−1 and Is≃3.2 kW/cm2 for CO2, and α0≃1.0 m−1 and Is≃3.0 kW/cm2 for a cw N2O mixing gasdynamic laser.
Catastrophic degradation of GaAlAs DH laser diodes
Authors: Imai H. , Morimoto M. , Sudo H. , Fujiwara T. , Takusagawa M.
Published: February 2003

The catastrophic degradation of GaAlAs DH laser diodes is examined with the application of pulsed or dc current. The dependence of the pulsewidth on the degradation is measured using samples with or without facet coating. The light output PD at which the catastrophic degradation occurs decreases with an increase in the pulsewidth in the pulsewidth range 100 nsec to 10–50 μsec, and PD is constant over the pulsewidth of 10–50 μsec. The sample with an Al2O3 film coating has the highest PD. Photoluminescence patterns of the active layer in degraded samples both with and without facet coating show the growth of DLD’s in the 〈110〉 direction from the vicinity of a facet in the stripe region.
Electroluminescence at the n-TiO2/electrolyte interface
Authors: Morisaki H. , Yazawa K.
Published: February 2003

We have observed electroluminescence at the n-TiO2/electrolyte interface under strong polarization of TiO2 electrodes above 8 V versus SCE. The quantum yield, obtained from current and intensity measurements at 10 V versus SCE, was in a range between 10−3 and 10−4. The emission spectrum, measured by optical glass filters, was found to be distributed in a range between 450 and 800 nm, the spectrum peak being approximately 630 nm, which is equivalent to a photon energy of 2.0 eV. This luminescence has been attained to the radiative recombination of electrons in some surface states with holes created in the valence band by electron tunneling.
Measurement of SAW attenuation on metals
Authors: Wakefield J. H. , Liesegang J.
Published: February 2003

The attenuation coefficients κ and wave speeds vs have been measured for SAW (surface acoustic waves) ∼5 MHz propagating on several polished flat polycrystalline metal surfaces. Laser interferometry techniques were used to measure standing-wave coefficients in such a way as to relate conveniently to a determination of both κ and vs.
Laser heating and magnetic compression of plasma in a fast solenoid
Authors: Hoida H. W. , Vlases G. C.
Published: February 2003

A low-β plasma column a few mm in diameter by 22 cm in length is heated by an axially directed CO2 laser to a high-β state in a fast rising solenoidal field. Successful heating depends on proper timing between the laser pulse and rising field. Typical conditions attained are a line energy density of 6 J/cm, T̄≈40 eV, and ne≈3×1017e−/cm3, with conditions quite uniform along the length. The heating suppresses instabilities which appear under certain conditions in the non-laser-heated case.
Turbulent flow measurement in the vicinity of a cation-selective membrane utilizing the Doppler shift of scattered laser radiation
Authors: Reich S.
Published: February 2003

An anemometric method to measure the velocity of fluid flow in the vicinity of a cation-selective membrane is described. It is shown that the turbulent phenomenon which develops on the depletion side of the membrane, beyond the critical current density point, is confined to a space region of ≃130 μm from the membrane surface; this turbulence is strongly coupled to the dissipation process of electric energy in the depletion region.
Stabilization of semiconductor laser outputs by a mirror close to a laser facet
Authors: Chinone N. , Aiki K. , Ito R.
Published: February 2003

Fluctuations of semiconductor laser outputs such as transient relaxation oscillations, external-mirror-induced fluctuations, or degradation-induced self-sustained pulsations are suppressed by placing a mirror close to a laser facet. The mirror-to-laser distances are 0.3–2.0 cm for effectively suppressing the fluctuations.
ac electroluminescence in thin-film ZnSe : Mn
Authors: Shah Jagdeep , DiGiovanni A. E.
Published: February 2003

ac electroluminescence from thin films of Mn-doped ZnSe, sandwiched between two insulating films, shows a hysteresis in light output versus applied voltage, similar to that observed in ZnS : Mn. We also find that the threshold voltage for light emission is approximately a factor of 2 smaller for ZnSe structures than for similarly prepared ZnS structures of identical dimensions.
On the formation of Ni and Pt silicide first phase: The dominant role of reaction kinetics
Authors: Canali C. , Catellani F. , Ottaviani G. , Prudenziati M.
Published: February 2003

4He+ backscattering spectrometry and x-ray diffractometry have been used to study the formation of Ni and Pt silicides in Si(xtl)/M film structures with different metal film thicknesses ranging from 800 to 5000 Å. Results clearly show that first the phase richer in metal (Ni2Si, Pt2Si) grows and continues to grow until all available metal is reacted, then the phase richer in Si (PtSi, NiSi) starts to grow. Present results prove that in Si(xtl)/Pt or Ni interactions the growth phase is determined by the reaction kinetics and that diffusion of metal atoms through Pt2Si and Ni2Si is fundamental in keeping the reaction going.
Deep center luminescence (1.02 eV) in GaAs/(GaAl)As epitaxial layers and double-heterostructure lasers
Authors: Metz S.
Published: February 2003

Various LPE GaAs/Ga1−XAlXAs layers and DH lasers of direct alloy composition (0⩽X≲0.35) have been excited by photoluminescence and current injection at 300 K, respectively. All samples emit a weak low-energy band (BIII), peaking at about 1.02 eV independent of material composition X and doping. The responsible deep-level centers therefore remain fixed energetically at 1.02 eV, relative to the (more distant) band edge, as the gap is varied. This striking feature and other characteristics support the hypothesis that BIII results from radiative recombination at defects which are very similar, if not identical, to those labeled E3 in literature on this
Theory of light emission from small particle tunnel junctions
Authors: Hone Daniel , Mühlschlegel B. , Scalapino D. J.
Published: February 2003

We study a simple model of light emission from inelastic electron tunneling into small metallic particles, here represented as spheres. Within a quasistatic approximation for the induced polarization in the electrodes, we calculate the radiated intensity as a function of frequency and direction.
On the synthesis of A-15 ’’Nb3Si’’ by ion implantation
Authors: Clapp Mireille Trevil , Rose R. M.
Published: February 2003

Ion implantation was used to introduce 20 at.% Si into an A-15 Nb3Al0.9Si0.1 substrate. The surface was depleted of Al by a diffusion anneal. The Al deficiency was replaced with Si by successive implantations. The surface structures were determined from reflection electron diffraction photographs. After depletion and implantation, the sample surfaces had a disordered bcc structure. A subsequent 800 °C anneal transformed these surfaces into A-15 Nb3Al0.2Si0.8 by epitaxial recrystallization.
Experimental measurement of the SAW properties of berlinite
Authors: Morency D. G. , Soluch W. , Vetelino J. F. , Mittleman S. D. , Harmon D. , Surek S. , Field J. C. , Lehmann G.
Published: February 2003

The surface acoustic wave properties of berlinite have been measured for the x-axis boule 92.75° cut. This cut was found to be temperature compensated at 32 °C. The velocity and coupling coefficient k2 were found to be 2747 m/sec and 0.003, respectively. The velocity and temperature coefficient of delay are in reasonable agreement with theory, while the value of k2 is lower than the theoretical value.
Far-ir heterodyne radiometric measurements with quasioptical Schottky diode mixers
Authors: Fetterman H. R. , Tannenwald P. E. , Clifton B. J. , Parker C. D. , Fitzgerald W. D. , Erickson N. R.
Published: February 2003

We have made heterodyne radiometric measurements with GaAs Schottky diode mixers, mounted in a corner-reflector configuration, over the spectral range 170 μm to 1 mm. At 400 μm, system noise temperatures of 9700 K DSB (NEP=1.4×10−19 W/Hz) and mixer noise temperatures of 5900 K have been achieved. This same quasioptical mixer has also been used to generate 10−7 W of tunable radiation suitable for spectroscopic applications.
Subpicosecond light pulses from a synchronously mode-locked dye laser with composite gain and absorber medium
Authors: Fehrenbach G. W. , Gruntz K. J. , Ulbrich R. G.
Published: February 2003

We report the generation of subpicosecond light pulses in a cw mode-locked Oxazine 750 dye laser, utilizing combined synchronous pumping and saturable dye absorption effects. The latter were realized by either fractional cavity length configurations or composite gain-absorber media, which allowed stable operation in the tuning range 750–835 nm.
Channeled-substrate-planar structure distributed-feedback semiconductor lasers
Authors: Kuroda T. , Yamashita S. , Nakamura M. , Umeda J.
Published: February 2003

Distributed-feedback Ga1−xAlxAs lasers with a channeled-substrate-planar structure are fabricated. They operate in single transverse and longitudinal modes. No spectral broadening or excess noise is observed under high-frequency modulation as a result of mode stabilization.
Low Si-contamination GaP LPE layers grown at 650 °C from indium solvent
Authors: Sugiura Toshifumi , Tanaka Akira , Sukegawa Tokuzo
Published: February 2003

High-quality GaP layers were obtained by liquid phase epitaxy at a low temperature, 650 °C, from indium solvent. We attribute the high quality of the LPE layers to the reduction in the concentrations of vacancies and unintentional impurities such as Si which would come from the growth system.
High-intensity infrared transmission limit in Hg1−xCdxTe
Authors: Jamison S. A. , Nurmikko A. V.
Published: February 2003

Studies of intensity-dependent transmission of pulsed radiation of nanosecond duration at 10.6 μm very near the band gap in n-Hg0.77Cd0.23Te at low temperatures show evidence of abrupt limiting behavior which manifests itself in no additional transmission for incident intensities exceeding approximately 200 kW/cm2 at T⩽20 K. Measurement of the spectral broadening in the transmitted radiation for excitation of nanosecond duration suggest that such self-enhanced ’’opacity’’ can be switched on in less than 500 psec. The surprisingly low observed threshold intensities are considered by examining the contribution from inelastic hot-electron collisions to the generation of excess free carriers.
Observation of grain-boundary migration using field ion microscopy
Authors: Eaton H. C. , Bayuzick R. J.
Published: February 2003

The field ion microscope is demonstrated to be a useful tool for studying the motion of grain boundaries in metals. Heating is accomplished by passing a current through a high-resistance specimen support loop. An example is shown of migration of a grain boundary in tungsten. The radius of curvature at the specimen apex was approximately 12 nm and displacements in the boundary as small as 1 nm are observed.
Fast neutralization of ion beams in the presence of transverse magnetic fields
Authors: Poukey J. W. , Humphries S.
Published: February 2003

A crucial problem in pulsed linear ion accelerators is the time-dependent space-charge neutralization of the ion beam by electrons from the walls. Analytic estimates and numerical simulation are used to discuss this problem, and it is found that in the presence of a magnetic field transverse (but not normal) to the ion flow, there is nearly complete neutralization on the scale of the ion beam rise time.
Numerical simulation of the nonlinear evolution of an exploded wire plasma
Authors: Hussey T. W. , Roderick N. F. , Faehl R. J.
Published: February 2003

Numerical simulations of exploded wire plasmas have been conducted using a two-dimensional (r-z) magnetohydrodynamic computer code for several experimental configurations. Recent results with an aluminium wire showing the development of the nonlinear sausage instability are presented. Short-wavelength modes are observed to grow and saturate initially, while longer wavelengths evolve later through nonlinear processes, particularly magnetic field diffusion. This behavior, as well as predicted energy output, appears to be consistent with experiment.
Epitaxial laser crystallization of thin-film amorphous silicon
Authors: Bean J. C. , Leamy H. J. , Poate J. M. , Rozgonyi G. A. , Sheng T. T. , Williams J. S. , Celler G. K.
Published: February 2003

Vapor-deposited amorphous silicon films of 4000 Å thickness have been epitaxially crystallized on (100) silicon substrates by pulsed Nd : YAG laser radiation of 125-nsec duration at power levels of 90–120 MW/cm2. The epitaxial layers were found to be defect free when examined by transmission electron microscopy and Rutherford backscattering. Patterned arrays of epitaxial crystal were produced by overlapping individual 39-μm laser pulse spots.
Magnetostatic forward volume wave reflection by a shallow groove on a YIG film
Authors: Parekh J. P. , Tuan H. S.
Published: February 2003

A field theory for the magnetostatic forward volume wave (MSFVW) reflectivity of a single shallow groove etched on top of an epitaxial YIG film is presented. The groove reflectivity is found to be significantly large considering that the groove is surface localized and shallow.
Q-switched ruby laser alloying of Ohmic contacts on gallium arsenide epilayers
Authors: Margalit Shlomo , Fekete Dan , Pepper David M. , Lee Chien-Ping , Yariv Amnon
Published: February 2003

Ohmic contacts of AuGe have been produced on GaAs epilayers by laser alloying. The contacts possess morphological and electrical properties which are superior to those formed by conventional alloying.
Elimination of stacking-fault formation in silicon by preoxidation annealing in N2/HCl/O2 mixtures
Authors: Hattori Takeshi , Suzuki Toshiharu
Published: February 2003

The formation of oxidation-induced stacking faults in the surface regions of silicon wafers can be eliminated by a short-period anneal in a dry nitrogen atmosphere containing small concentrations of HCl and oxygen in the same furnace where subsequent oxidation will be carried out. This preoxidation anneal results in the prevention of fault nucleation without causing any problem like a nitridation reaction, an etch-pit formation, and a blotchy appearance on the silicon surface.
Avalanche breakdown voltages for III-V semiconductors
Authors: Hauser J. R.
Published: February 2003

Breakdown voltages have been calculated for abrupt p-n junctions in the nine III-V semiconductors of AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs, and InSb. Parameters needed in the breakdown voltage calculations such as the mean free path for scattering and the average phonon loss have been evaluated using a Monte Carlo transport calculation at electric field values characteristic of breakdown.
The nucleation of high-T
c Nb3Ge in the presence of impurities
Authors: Gavaler J. R. , Ashkin M. , Braginski A. I. , Santhanam A. T.
Published: February 2003

Analyses of high-Tc Nb3Ge films show that they all have a peak in oxygen concentration near the substrate-film interface and that their lattice parameters in that region are abnormally large. It is proposed that high-Tc Nb3Ge is a metastable phase which is formed via a homoepitaxial process from a large lattice parameter A15 Nb-Ge phase. This phase near the interface is believed stable due to an expanded lattice resulting from the presence of impurities.
Anomalous plasma resistivity in prepulsed flashlamp discharges
Authors: Marotta A. , Galvão R. M. O.
Published: February 2003

It is shown that the V-i characteristic of discharges in flashlamps operating in the prepulsed mode at high current densities follows the relationship V=K0i0.85. This result is interpreted in terms of the Sagdeev-Galeev anomalous resistivity due to current-driven ion-acoustic turbulence.
Nonlinear generation of Lyman-alpha radiation
Authors: Mahon Rita , McIlrath T. J. , Koopman David W.
Published: February 2003

Tunable narrow-band Lyman-alpha radiation (∼1216 Å) has been generated by frequency tripling in krypton. A near-diffraction-limited tunable 15-nsec 10-MW input at 3648 Å was used to generate ∼3.6×1011 photons (60 W) per pulse at 1216 Å. Measurements of the output as a function of gas pressure give the refractive index for krypton at 1216 Å, demonstrating its negatively dispersive character.
Shadow sputtered diffraction-limited waveguide Luneburg lenses
Authors: Yao S. K. , Anderson D. B.
Published: February 2003

Thin-film Luneburg lenses are formed by sputtering through a circular shaped mask. A series of computer simulation programs have been developed for the synthesis of the shadow mask contour to produce the necessary thin-film lens thickness profile. Diffraction-limited results have been obtained for guided wave optical lenses.
Liquid phase epitaxial In1−xGaxAsyP1−y lattice matched to 〈100〉 InP over the complete wavelength range 0.92⩽λ⩽1.65 μm
Authors: Pollack M. A. , Nahory R. E. , DeWinter J. C. , Ballman A. A.
Published: February 2003

A two-phase supercooled solution method is described for the LPE growth of In1−xGaxAsyP1−y on 〈100〉 InP over the entire range of lattice-matched compositions, 0⩾y<1, 0?x<0.47. Liquid and solid compositions, distribution coefficients, and band-gap data which may be used to design specific devices are presented.
Insulating carbon coating on (AlGa)As DH laser facets
Authors: Furuse Takao , Suzuki Tohru , Matsumoto Shohei , Nishida Katsuhiko , Nannichi Yasuo
Published: February 2003

Insulating carbon films were developed to prevent facet deterioration of (AlGa)As DH lasers. Chemically durable optically transparent carbon film was obtained by a carbon ion-beam deposition technique. Stable lasing operations have been obtained with carbon coated lasers for over 6000 h.
Low-current proton-bombarded (GaAl)As double-heterostructure lasers
Authors: Bouley J. C. , Delpech Ph. , Charil J. , Chaminant G. , Landreau J. , Noblanc J. P.
Published: February 2003

Low-current cw stripe double-heterostructure (DH) lasers have been realized using a shallow proton-bombardment technique; unlike usual proton DH lasers they involve a resistive p (GaAl)As confinement layer and a rather highly doped GaAs active region both to reduce spreading current and stripe injected carrier outdiffusion. Threshold currents are on the order of 50 mA for a 12-μm-wide by 200-μm-long cavity.
Evidence for impact-ionized electron injection in substrate of n-channel MOS structures
Authors: Matsunaga Junichi , Kohyama Susumu
Published: February 2003

Impact-ionization current during saturation mode operation is widely known in MOS devices. Although not noted in previous work, minority carriers also may be observed in the substrate, together with hole current. These minority carriers can degrade the MOS depletion layer lifetime, thus limiting the performance of MOS dynamic devices. A series of experiments utilizing the C-t method, the MOS capacitor surface potential measurement, and the charge-coupled device (CCD) is described, which provides evidence for electrically generated electrons in the substrate of n-channel MOS structures.