bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of LPE growth techniques on the alloy composition of InGaAsP
Authors: Feng M. , Cook L. W. , Tashima M. M. , Windhorn T. H. , Stillman G. E.
Published: February 2003

In experiments on the LPE growth of InGaAsP on (100) -InP substrates, it has been found that constant-composition epitaxial layers can be grown at constant temperature using the step-cooling technique, while the equilibrium-cooling, supercooling, and two-phase-solution techniques which involve growth under changing temperatures all result in grading of the alloy composition. The lattice constants and energy gaps of epitaxial layers grown using the step-cooling technique are independent of the amount of step cooling but are dependent on the growth temperature.
Shock focusing in implosions of inertial fusion model targets
Authors: Perry F. C. , Mix L. P. , Toepfer A. J.
Published: February 2003

Implosions of high-gain targets for inertial confinement fusion must be highly spherically symmetric for efficient ignition. Using a single relativistic electron beam at low power (∼0.3 TW) and cylindrical targets, we have experimentally shown that loading asymmetries generate strong implosion asymmetries, resulting in poor convergence ratios. By introducing a nonspherical variation in the shell radius and thickness (shimming), the implosion symmetry is radically improved at one time during the implosion. The effect is explained by a shock focusing mechanism whereby ultrahigh pressure—0.9 Tpa (9 Mbar) —is achieved on one side of the target.
Low-threshold 1.25-μm vapor-grown InGaAsP cw lasers
Authors: Olsen G. H. , Nuese C. J. , Ettenberg M.
Published: February 2003

Vapor-grown double-heterojunction lasers of InGaAsP/InP have been prepared with cw room-temperature threshold currents of 85 mA and differential quantum efficiencies exceeding 50% at 1.25 μm. From several lasers, fundamentaal-lateral- and fundamental-longitudinal-mode operation have been observed over moderate current ranges. Over 1000 h of room-temperature cw operation has been observed to date without significant degradation.
Absorption processes in the XeCl laser
Authors: Champagne L. F. , Palumbo L. J. , Finn T. G.
Published: February 2003

Transient absorption in Ne/Xe/HCl mixtures and various rare gas combinations are measured. The observed results are matched with a numerical model to determine the dominant absorbing species in the XeCl laser. In pure neon plasmas Ne*2 is a dominant absorber. Addition of xenon greatly reduces this absorption through the mechanism of Penning ionization. Absorption is not changed by adding HCl to the optimum neon-xenon concentration.
Efficient hologram recording in LiNbO3 : Fe using optical pulses
Authors: Chen Che-Tsung , Kim Dae M. , von der Linde D.
Published: February 2003

A Q-switched frequency-doubled Nd : YAG laser was used to record holograms in LiNbO3 : Fe. For 1% diffraction efficiency, only 50 mJ/cm2 was needed, as compared to 500 mJ/cm2 for cw recording. Induced absorption, comparable in magnitude with the linear absorption at 647 nm, was observed during hologram recording. This indicates the existence of secondary absorption centers in LiNbO3 : Fe. Their contribution to the enhanced photorefractive effect is discussed.
HgBr and HgI B-state quenching rate constants
Authors: Eden J. G. , Waynant R. W.
Published: February 2003

The rate constants for quenching of the B states of HgBr and HgI by the rare gases and simple halogenated molecules have been measured. The experimental approach consisted of photodissociating either HgBr2 or HgI2 (in the presence of the desired quenching gas) and recording the subsequent radiative decay of the HgX (X=Br or I) excited-state population. The large rate constant determined for two-body destruction of HgBr (B) by Hg (1.3×10−10 cm3 sec−1) and bromine donors (Br2 : 5.5×10−10 cm3 sec−1) enhances the attractiveness of HgBr lasers pumped by dissociative excitation of HgBr2.
Infrared-to-optical image conversion by Bragg reflection from thermally induced index gratings
Authors: Martin G. , Hellwarth R. W.
Published: February 2003

We have observed efficient reproduction at visible wavelengths of 1.06-μ images. We employed a phase-matched four-wave mixing process in which three waves at ν, ν, and ω mix to generate a fourth wave at ω, with no resonant conditions in either frequency. The image conversion was seen with each of the 14 liquids tried as a nonlinear medium and also with a glass. Thermal index changes were the dominant mechanism.
GaxIn1−xAsyP1−y/InP rib-waveguide injection lasers made by one-step LPE
Authors: Doi A. , Chinone N. , Aiki K. , Ito R.
Published: February 2003

A new fabrication method and characteristics of a rib-guide GaInAsP/InP DH laser are described. The active layer of the rib-guide structure is grown directly on a grooved InP substrate by one-step liquid phase epitaxy in which phosphorus vapor is introduced in order to prevent the decomposition of the substrate. Stable transverse-mode operation is obtained reproducibly up to 1.5 times threshold current. A preliminary life test indicates that the rib-guide lasers fabricated without a buffer layer should be as reliable as conventional lasers with a buffer layer.
Flicker noise in highly doped semiconductors
Authors: van der Ziel A.
Published: February 2003

It is proposed to explain the observation of Hooge and Vandamme of flicker noise in highly doped semiconductors in terms of a number-fluctuation model governed by a surface effect. While this model cannot be proven at present, it has the advantage that it is compatible with the absence of flicker noise in JFET’s, whereas the mobility fluctuation model is not.
Electrical switching and memory phenomena in Cu-TCNQ thin films
Authors: Potember R. S. , Poehler T. O. , Cowan D. O.
Published: February 2003

Stable and reproducible current-controlled bistable electrical switching has been observed in polycrystalline organic semiconducting films. The effect has been observed in a lamellar structure with a film of microcrystalline Cu-TCNQ between Cu and Al electrodes where the Cu-TCNQ is grown on a Cu substrate via a spontaneous electrolysis technique. The switching effect is insensitive to moisture and is observed over a large temperature range. The current-voltage characteristics reveal an abrupt decrease in impedance from 2 MΩ to less than 200 Ω at a field strength of 4×103 V/cm. The transition from a high- to low-impedance state occurs with delay and switching times of approximately 15 and 10 nsec, respectively. Switching with high-power dissipation yields a low-impedance memory state which can be erased by application of a short current pulse. An interpretation of this behavior is based on the bulk properties of the mixed valence semiconductor Cu-TCNQ.
Deuterium separation with 1400-fold single-step isotopic enrichment and high yield by CO2-laser multiple-photon dissociation of 2,2-dichloro-1,1,1-trifluoroethane
Authors: Marling Jack B. , Herman Irving P.
Published: February 2003

The compound 2,2-dichloro-1,1,1-trifluoroethane, CF3CHCl2, has been selected in an exhaustive search as the most promising working material for potentially viable laser separation of deuterium. Highly isotopically selective absorption in CF3CDCl2 occurs near 10.2 and 10.6 μm, accessible with the normal CO2 laser. The single-step deuterium isotopic enrichment factor attains a value of 1400 at a fluence of 10 J/cm2 for the dominant photoproduct, trifluoroethene (CF2=CFD and CF2=CFH). The probability for CF3CDCl2 dissociation into CF2=CFD photoproduct occurs with a fluence threshold near 1.5 J/cm2 and appears to saturate near 100% yield above 15 J/cm2. Liquid-phase base-catalyzed H/D exchange occurs rapidly with water without hydrolysis to permit redeuteration of the CF3CHCl2 working material.
Application of ABAC-combined x-ray step-scanning section topography for characterization of lattice imperfections in silicon
Authors: Kawado Seiji , Aoyama Jun-ichi
Published: February 2003

An x-ray step-scanning topographic technique combined with an automatic Bragg-angle control (ABAC) system has been developed and applied to the study of crystal perfection of silicon wafers subjected to copper decoration, phosphorus diffusion, and thermal oxidation. This technique has revealed exact spatial configurations of individual lattice imperfections such as swirl defects, diffusion-induced dislocations, oxidation-induced stacking faults, and precipitates.
Monolithic integration of an injection laser and a metal semiconductor field effect transistor
Authors: Ury I. , Margalit S. , Yust M. , Yariv A.
Published: February 2003

A new laser structure, the ’’T-laser’’, has been monolithically integrated with a MESFET on a semi-insulating GaAs substrate. Integration is achieved by means of a compatible structure in which the optically active layer of the laser also serves as the electrically active layer of the MESFET. Direct modulation of the laser by means of the transistor is demonstrated.
Fast photoconductor coupled liquid-crystal light valve
Authors: Samuelson L. , Wieder H. , Guarnieri C. R. , Chevallier J. , Onton A.
Published: February 2003

Short low-energy pulses of laser light have been used to switch spots on a liquid crystal (LC) through a coupled photoconductive film of glow-discharge-produced amorphous Si (GD/a-Si). The a-Si responds rapidly to a light pulse, yet retains sufficient photoconductivity in the slow portion of the decay to match the slower response time of the LC. Spots have been written with laser pulses 10 μs long, about 10−3 the response time of the LC, and with a pulse energy of 1–10 μJ/cm2, less than 10−4 the energy required for thermal writing.
Phonon-sideband MO-CVD quantum-well AlxGa1−xAs-GaAs heterostructure laser
Authors: Holonyak N. , Kolbas R. M. , Laidig W. D. , Altarelli M. , Dupuis R. D. , Dapkus P. D.
Published: February 2003

Laser operation (4.2–300 °K) of multiple-quantum-well AlxGa1−xAs-GaAs heterostructures on a phonon (LO) sideband ∼36 meV below the lowest confined-particle transitions is described. Phonon-sideband laser data are presented on two different metalorganic chemical-vapor-deposited (MO-CVD) quantum-well heterostructures with four GaAs active regions (Lz∼50 and ∼90 Å) coupled by three AlxGa1−xAs (x∼0.35) barriers.
Preparation of Sn-doped In2O3 (ITO) films at low deposition temperatures by ion-beam sputtering
Authors: Fan John C. C.
Published: February 2003

High-quality films of Sn-doped In2O3 (ITO) have been prepared by ion-beam sputtering at deposition temperatures below 100 °C. As in the case of rf-sputtered films, the electrical and optical properties of these films depend strongly on the O2 partial pressure during deposition. As-deposited films with low electrical resistivity (∼5.5×10−4 Ω cm), high visible transmission (≳80%), and high infrared reflectivity at 10 μm (∼84%) have been obtained at O2 pressures of (2–3) ×10−5 Torr by deposition on both glass and Mylar substrates.
Vacuum-evaporated conducting ZnS films
Authors: Olsen L. C. , Bohara R. C. , Barton D. L.
Published: February 2003

Conductive crystalline films of ZnS have been deposited by coevaporating ZnS and Al, or In. As-deposited conductive films have been obtained on occasion. Conductive films are consistently obtained with heat treatment subsequent to deposition. Typically, film resistivities are in the range 1–10 Ω cm. Hall mobilities on the order of 775 cm2 V−1 sec−1 have been measured. The results reported here suggest that with improved control of deposition parameters, conductive crystalline ZnS films can be obtained (as deposited) with two-source thermal evaporation.
Interstitial supersaturation near phosphorus-diffused emitter zones in silicon
Authors: Strunk H. , Gösele U. , Kolbesen B. O.
Published: February 2003

Bipolar transistors with consecutively diffused boron base and phosphorus emitter showing the ’’emitter-push effect’’ have been investigated by transmission electron microscopy. The analysis of isolated dislocation helices in the emitter and base regions indicates the presence of a self-interstitial supersaturation in front of the phosphorus-diffused zone. This result refutes the widely accepted explanation of the ’’emitter-push effect’’ in terms of a phosphorus-induced vacancy supersaturation.
Laser annealing of indium-implanted Pb0.8Sn0.2Te films
Authors: Bahir G. , Bernstein T. , Kalish R.
Published: February 2003

The annealing of indium-implanted thin epitaxial films of Pb0.8Sn0.2Te (LTT) by means of pulses from a Q-switched CO2 laser is reported. The results of the annealing are studied by channeling and interference-contrast microscopy. The annealing seems to proceed through the melting-liquid phase recrystallization mechanism which leads to crystals of quality similar to those obtained by conventional furnace annealing. Interference phenomena, related to the fact that the wavelength of the laser radiation is comparable to the film thickness, are observed.
Observation of changes in the electronic density of states at a Si (111) surface during adsorption of oxygen by Auger electron spectroscopy
Authors: Morgen P. , Onsgaard J. H. , Tougaard S.
Published: February 2003

The adsorption of oxygen on a Si (111) surface is accompanied by significant changes in the local electronic densities of states. These effects have been monitored as changes in the spectral distribution of emitted L2,3 VV Auger electrons from pure and oxygen-covered surfaces. Oxygen coverages varying from 0 to slightly below monolayer coverage (237L) have been employed. The present results are compared with data from recent sputter-profiling studies of the Si-SiO2 interface, showing similar behaviors in the two types of experiments.
Minimum Al0.5Ga0.5As-GaAs heterojunction width determined by sputter-Auger techniques
Authors: Garne C. M. , Su F C. Y. , Spicer W. E. , Edwood P. D. , Miller D. , Harris J. S.
Published: February 2003

Two intimately connected parameters are investigated: the abruptness of MBE heterojunctions and the minimum depth resolution of the sputter-Auger technique. Using 250-eV Ar+ ions and monitoring the Al LVV Auger transition, the sharpest interface measured to date (13–15 Å) is obtained. After correcting for the electron escape depth, a minimum interface width of 9 Å is obtained. Large increases in interface broadening with increasing Ar+ ion energies are observed.
Hole transit in Teflon films
Authors: Gross B. , Sessler G. M. , von Seggern H. , West J. E.
Published: February 2003

The transit of excess holes through 25-μm Teflon films has been observed. The holes are generated by electron-pulse ionization in the near-surface region of the samples. From the transit time we determine a mobility of 2×10−9 cm2/V s, independent of field, carrier density, penetration depth of the primary electrons, and length of the electron pulse. Results are discussed in terms of the conventional concept of trap-modulated mobility and of the alternative theory of dispersive hopping.
A new blue-green excimer laser in XeF
Authors: Bischel W. K. , Nakano H. H. , Eckstrom D. J. , Hill R. M. , Huestis D. L. , Lorents D. C.
Published: February 2003

A new blue-green excimer laser has been demonstrated on the C-A transition in XeF, with an output energy of greater than 1 mJ. Xe*2 excimer fluorescence at 172 nm was used to photodissociate XeF2, producing XeF[B (1/2)] and XeF[C (3/2)]. The B (1/2) state was collisionally relaxed to the C (3/2) state with an Ar buffer. Lasing then occurs sequentially on the B (1/2) -X (1/2) and C (3/2) -A (3/2) transitions. Measurements of the C-A laser spectrum showed a peak wavelength of 483 nm with a bandwidth of 12 nm. This new laser is potentially highly efficient and scalable and should be tunable over a bandwidth greater than 40 nm.
Long-wavelength InGaAsP avalanche photodiodes
Authors: Yeats R. , Chiao S. H.
Published: February 2003

InGaAsP avalanche photodiodes have been fabricated with uniform high-speed gains of 40 and quantum efficiencies up to 63% at 1.05 μm. At high gains increased leakage current leads to excessive shot noise. Noise measurements indicate that the increased leakage current arises from a uniformly multiplied but increasing value of the primary (i.e., premultiplication) leakage current. The increase in leakage current is thought to be due to surface effects. The size of the leakage current is shown to lead to a prediction of gain saturation in approximate agreement with the observed maximum gain.
SEM observations of SAW resonator transverse modes
Authors: Tanski W. J. , Wittels N. D.
Published: February 2003

The acoustic standing-wave antinode structure has been observed using SEM voltage contrast in a two-port SAW resonator on ST-cut quartz. All transverse resonant modes up to seventh order are visible and agree qualitatively with theoretical predictions. Some phase effects, including antinode shifts near resonance and alternation of antinode phase, have been seen. This technique may be useful in understanding and diagnosing SAW resonator behavior.
X-ray determination of strain and damage distributions in ion-implanted layers
Authors: Speriosu V. S. , Glass H. L. , Kobayashi T.
Published: February 2003

Quantitative values for the strain and damage distributions in ion-implanted layers are obtained by the application of a kinematical model of x-ray diffraction. Distributions are synthesized by matching experimental and theoretical rocking curves. The method is applicable to ion-implanted, diffused, or as-grown multilayer thin structures.
Background carrier concentration and electron mobility in LPE In1−xGaxAsyP1−y layers
Authors: Greene P. D. , Wheeler S. A. , Adams A. R. , El-Sabbahy A. N. , Ahmad C. N.
Published: February 2003

Lattice-matched and nominally undoped layers of In1−xGaxAsyP1−y were grown by liquid-phase epitaxy on semi-insulating (100) InP substrates. The background carrier concentration for a range of compositions was about 2×1016 cm−3 when unbaked melts were used, but with prebaking 2.8×1015 cm−3 was achieved. The electron mobility data, obtained over the temperature range 77–300 K using magnetic fields up to 9 T, have been interpreted in terms of polar-optical phonon, alloy, and ionized impurity scattering. For midrange alloys of this purity, alloy scattering was found to be more significant than ionized impurity scattering. The alloy scattering potential is about 0.6 eV for alloys with y=0.5.
Study of surface crystallinity and stoichiometry of laser-annealed GaAs using time-resolved reflectivity and channeling
Authors: Venkatesan T. N. C. , Auston D. H. , Golovchenko J. A. , Surko C. M.
Published: February 2003

The surface crystallinity and stoichiometry of tellurium-implanted GaAs annealed with a frequency-doubled Nd:glass laser using time-resolved reflectivity and channeling measurements has been studied. By optimizing the duration of the liquid melt, depending on the implant dose, it has been possible to laser anneal implanted layers in uncapped GaAs with good surface crystallinity and minimal loss of arsenic due to surface decomposition. We propose a qualitative model of arsenic evaporation at the surface and subsequent replacement by arsenic displaced from the bulk by the tellurium which explains the dependence of the optimum melt duration on the dose of the implant.
Optimal cavity design for low-threshold-current-density operation of double-heterojunction diode lasers
Authors: Botez Dan
Published: February 2003

A simple and accurate closed-form expressed for the threshold-current density Jth in symmetric DH structures is presented. The novel expresion allows analytical solutions for do, the active-layer thickness corresponding to minimum threshold-current density. Optimization of the cavity thickness for minimum Jth is presented for wide variations in cavity length (100–500 μm) and facet reflectivity values. The analytical formulas are applied to the AlGaAs/GaAs system and extended to the InGaAsP/InP system. By using previously published experimental results, a linear gain-current relationship is estimated for InGaAsP (λ=1.2–1.3 μm), and thus it is found that do should vary between 0.12 and 0.20 μm as the cavity parameters (length and facet reflectivity) change; and that minimum Jth values should be comparable to the Jth values for AlGaAs lasers with the same cavity parameters.
On the scaling law of plasma temperature versus laser flux
Authors: Sinha B. K. , Gopi N.
Published: February 2003

The experiments were conducted with a 50-MW 60-ns ruby laser to study the variation of plasma temperature with laser flux for a carbon and polyethylene plasma in a purely collisional regime. The plasma temperature showed a φ2/9 dependence on laser flux in the intensity regime 2×1010 to 5×1011 W/cm2. Results are discussed with reference to the scaling laws obtained by different workers in different flux regimes on the basis of collisional and noncollisional absorption.
Proton radiation effects on Cr-MIS single-crystal Si solar cells
Authors: Ferraglio R. , Anderson W. A.
Published: February 2003

Cr-MIS solar cells on single-crystal Si, with a 2-cm2 area and approximately 10% efficiency, have been subjected to 1.0- and 1.6-MeV proton radiation at total dosages of up to 3.3×1013 p/cm2. Photovoltaic studies reveal characteristic short-circuit current and open-circuit voltage degradation similar to proton-irradiated junction-type solar cells. (See H. Y. Tada and J. R. Carter, Solar Cell Radiation Handbook, JPL Publication 77-56, 1977.) Spectral response measurements reveal output decay primarily due to minority-carrier diffusion-length decreases of up to 96%.
A 490-nm XeF electric discharge laser
Authors: Fisher C. H. , Center R. E. , Mullaney G. J. , McDaniel J. P.
Published: February 2003

Lasing at 490 nm in the broadband XeF (C 3/2→A 3/2) transition has been achieved in He/Xe/NF3 gas mixtures excited by a uv preionized electric discharge. Measurements of the C→A laser spectrum show a bandwidth of approximately 40 nm centered around 490 nm, indicating that the laser should be tunable over a wide spectral region in the visible.
Phonon-assisted recombination in a multiple-quantum-well LPE InP-In1−xGaxP1−zAsz heterostructure laser
Authors: Rezek E. A. , Chin R. , Holonyak N. , Kirchoefer S. W. , Kolbas R. M.
Published: February 2003

By means of computer-controlled liquid-phase epitaxy, multiple-quantum-well InP-In1−xGaxP1−zAsz (x∼0.13, z∼0.29) heterostructures of uniform well (Lz∼160 Å) and coupling barrier size are grown and are examined in photoluminescence. Laser operation (77 °K) of a six-well five-barrier undoped quaternary quantum-well heterostructure is identified an LO phonon energy (1×h/ωLO∼30 meV) below the lowest confined-particle transitions (No. 1 e→hh, E1) or at energy h/ω∼E1−h/ωLO.
Surface and bulk order parameters of a nematic liquid crystal
Authors: Mada Hitoshi , Kobayashi Shunsuke
Published: February 2003

The measurements of the anisotropy of the refractive index have been made for heptyl-cyanobiphenyl (7CB) at the surface as well as in the bulk by the interferometric method. Using these data, order parameters S̄ at the surface and S in the bulk were calculated. The results show that S̄ is slightly larger than S in the nematic temperature region. S becomes zero in the isotropic region; nevertheless, the order parameter at the surface, S̄, still has a finite value even at temperatures above the clearing point.
Kinetics of vacuum-ultraviolet continuum from a high-pressure He fast discharge
Authors: Gand M. , Bouchoule A. , Stevefelt J.
Published: February 2003

The kinetics of atomic and molecular excited states following a fast discharge in pure high-pressure helium are resolved on a nanosecond time scale by emission and absorption spectroscopy. Evidence is presented indicating that the Hopfield continuum (600–1100 Å) radiation occurs as a terminal process in a collisional-radiative cascade subsequent to the electronic recombination of He+2 ions. The radiated peak power in this wavelength range reaches several kW at atmospheric pressure.
Role of the III(1/2) -II(1/2) transition in rare-gas–halide kinetics
Authors: Julienne P. S. , Krauss M.
Published: February 2003

Rare-gas–halide spectra have previously been analyzed in terms of the strong III  (1/2) -I  (1/2) lasing transition and the weaker II  (3/2) -I  (3/2) broad continuum. However, the III  (1/2) -II  (1/2) transition is also a broad continuum that strongly overlaps the II(3/2) -I(3/2) transition and has an Einstein coefficient of a similar magnitude. The existence of this transition requires a reinterpretation of previous kinetic data on ArF, KrF, XeF, and XeCl. Simultaneous energy extraction from both the III  (1/2) and II(3/2) states should be possible for lasing in the broad continuum.
Crystallographic orientation of silicon on an amorphous substrate using an artificial surface-relief grating and laser crystallization
Authors: Geis M. W. , Flanders D. C. , Smith Henry I.
Published: February 2003

Uniform crystallographic orientation of silicon films, 500 nm thick, has been achieved on amorphous fused-silica substrates by laser crystallization of amorphous silicon deposited over surface-relief gratings etched into the substrates. The gratings had a square-wave cross section with a 3.8-μm spatial period and a 100-nm depth. The 〈100〉 directions in the silicon were parallel to the grating and perpendicular to the substrate plane. We propose that orientation of overlayer films induced by artificial surface patterns be called graphoepitaxy.
The preparation of GaAs thin-film optical components by molecular beam epitaxy using Si shadow masking technique
Authors: Tsang W. T. , Ilegems M.
Published: February 2003

In this letter, we further substantiate one of the very important advantages of molecular beam epitaxy (MBE) over liquid-phase epitaxy (LPE) and chemical vapor-phase deposition (CVD), namely, the ability to incorporate shadow masking during epitaxial growth, by fabricating several important thin-film optical components. These include two-dimensional optical waveguide tapered couplers as narrow as 2 μm, optical horns having absolutely featureless mirrorlike surfaces, and waveguide widths in the submicrometer range, and Luneburg lenses having perfect symmetry, extremely smooth surface, and very gentle transition.
Steady-state electron and hole space charge distribution in LPCVD silicon nitride films
Authors: Hampton F. L. , Cricchi J. R.
Published: February 2003

Trapped electron and hole space charge distributions in silicon nitride are derived from steady-state measurements of the change in flatband voltage versus the maximum field in the nitride. These measurements coupled with the Arnett-Yun model provide a good relative measure of the hole and electron trap densities, trapping lengths, and cross sections. Significant differences between hole and electron values at 25 and 175 °C were observed.
Efficient shallow-homojunction GaAs solar cells by molecular beam epitaxy
Authors: Fan John C. C. , Calawa A. R. , Chapman Ralph L. , Turner George W.
Published: February 2003

Conversion efficiencies up to 16% at AM1 have been obtained for molecular beam epitaxy (MBE) GaAs solar cells utilizing a shallow-homojunction n+/p/p+ structure without a GaAlAs window. The n+, p, and p+ GaAs layers were all grown by MBE on single-crystal p+ GaAs substrates. Cell metallization was performed by electroplating, and an antireflection coating was formed by anodic oxidation of the n+ layer. These cells are the first efficient MBE solar cells of any type to be reported.
The effects of neutron irradiation on a superconducting metallic glass
Authors: Kramer E. A. , Johnson W. L. , Cline C.
Published: February 2003

The effects of fast neutron irradiation on a superconducting metallic glass (Mo0.6Ru0.4)82B18 have been studied. Following irradiation to a total fluence of 1019 n/cm2, Tc increases from 6.05 to 6.19 K, and the width of the transition decreases sharply. The density of the material decreases by 1.5%, and the x-ray scattering intensity maxima are broadened. An improvement in the ductility of the samples is observed which together with the other observations suggests the production of defects having atomic scale dimensions and characterized by excess volume.
Electrochromic iridium oxide films prepared by reactive sputtering
Authors: Schiavone L. M. , Dautremont-Smith W. C. , Beni G. , Shay J. L.
Published: February 2003

We report the preparation and electrochromic properties of iridium oxide films deposited by reactively sputtering iridium in a humidified oxygen discharge. These sputtered iridium oxide films (SIROFs) have the fast coloring and bleaching kinetics and excellent stability previously observed for anodically grown iridium oxide films (AIROFs). SIROFs deposited on SnO2-coated glass can be modulated from clear to blue-gray with properties similar to those of AIROFs. In addition, SIROFs deposited on metal substrates exhibit a variety of colors which can be electrically altered. This adds a new dimension to the range of potential applications for iridium oxide displays.
Frequency stabilization of 0.633-μm line with the aid of 3.39-μm line locked to CH4
Authors: Nakazawa Masataka , Nakamura Jun-ichi , Musha Toshimitsu
Published: February 2003

0.633- and 3.39-μm lines were brought into simultaneous oscillation with a He-Ne laser. The 3.39-μm line was locked to the saturated absorption line of CH4 to control the cavity length, as a result of which the 0.633-μm line was also frequency stabilized. The frequency stability of the 0.633-μm line was better than 4.2×10−9/h, which is the stability of a reference laser HP 5500C.
Cd2 as a 470-nm absorber
Authors: Stevens Walter J.
Published: February 2003

Multiconfiguration self-consistent-field calculations have been carried out on all the valence states, low-lying rydberg states, and charge-transfer states of Cd2. Like the other Group IIb dimers studied thus far, the lowest excimer level was found to be a 3Πg metastable state that acts as a reservoir for molecular excitation energy. Strong absorptions between this reservoir state and a bound 3Πu charge-transfer state are predicted in the vicinity of 470 nm. Weaker, but still significant absorptions, are predicted between the laser state (3Σ+u) and a repulsive 3Σ+g state at the same wavelength. The predicted absorptions could seriously impair laser applications of Cd2 and CdHg.
The origin of the broadband emission of XeF
Authors: Rokni M. , Jacob J. H. , Hsia J. C. , Trainor D. W.
Published: February 2003

In this letter we report the results of our investigation into the origin of the broadband emission, centered about 460 nm, from XeF*. This emission has been investigated as a function of mixture ratio and pressure. The gas mixtures were excited by a high-energy electron beam. From the high-pressure data there is evidence of additional emission from states other than XeF(B) and XeF(C) when the buffer gas is Ar and Ne. We have tentatively assigned this emission as originating from the excited triatomics ArXeF* and NeXeF*.
Discovery of a new reversible electrochromic effect
Authors: Pfluger P. , Künzi H. U. , Güntherodt H.-J.
Published: February 2003

A new electrochromic effect based on the electrochemical intercalation of graphite is described. This effect seems to have a promising potential for applications in display devices.
Cyclotron resonance in n-type In1−xGaxAsyP1−y
Authors: Brendecke H. , Störmer H. L. , Nelson R. J.
Published: February 2003

First experimental data are presented on the nonparabolicity of the conduction band of In1−xGaxAsyP1−y lattice matched to InP. The values for the effective mass, determined from our energy-dependent measurements, are smaller than all previously reported values. The nonparabolicity of the conduction band is much stronger than previously assumed.
Calculated and measured efficiencies of thin-film shallow-homojunction GaAs solar cells on Ge substrates
Authors: Fan John C. C. , Bozler Carl O. , Palm Barbara J.
Published: February 2003

By using a simple analytical model for GaAs solar cells with the nu+/p/p+ shallow-homojunction structure, we have obtained good between compter calculations and experimental data for the external quantum efficiency and AM1 conversion efficiency of thin-film GaAs cells with different values of + layer thickness grown on Ge substrates. The calculations yield values for material properties of the GaAs layers composing the cells and also permit the optimization of cell design parameters. In addition, the agreement between calculation and experiment demonstrates that the Ge substrates play a passive role. Thus we have succeeded in fabricating efficient thin-film GaAs solar cells on non-GaAs substrates.
Fatigue effects in unidirectional composites: applications to Nb3Sn superconductors
Authors: Cogan Stuart F. , Rose Robert M.
Published: February 2003

A computer-simulated model for the fatigue behavior of multifilamentary unidirectional composites is presented. It is applicable to two-component composites with perfectly elastic filaments in a ductile matrix, and considers both applied cyclic stresses and strains. Information regarding the change in residual stress state, matrix yield strength, and the number of cycles necessary to stabilize properties by the achievement of totally elastic strains (shakedown), or to reach some preassigned failure stress in the matrix, can be determined. Results obtained are applied directly to the fatigue behavior of multifilamentary Nb3Sn superconducting composites.
A simple theory of resonance amplitudes in Josephson interferometers
Authors: Guéret P.
Published: February 2003

In this letter, we present a theory of interferometer resonance. This theory consists of solving the interferometer equations in the sinusoidal approximation. An expression for the resonance amplitude is obtained which is valid for all Q values and gives perfect agreement with computer simulations. The implications of these results for SFQ memory cells are also discussed.
Low-noise 86–88-GHz traveling wave maser
Authors: Sollner T. C. L. G. , Clemens D. P. , Korzeniowski T. L. , McIntosh G. C. , Moore E. L. , Yngvesson K. S.
Published: February 2003

A traveling wave maser using iron doped rutile (Fe3+: TiO2) has been developed for a signal frequency of 86–88 GHz. The 3-dB bandwidth is 40–50 MHz for an electronic gain of 36 dB and a net maser gain of 15–20 dB. Hexagonal aluminum substituted strontium ferrite was used for isolation. A unique overmoded ridge guide structure is used to match pump and signal power to the active material from 30 to 120 GHz. The maser noise temperature has been measured as TMaser =20±10 K.
Tunable single-longitudinal-mode operation of an injection-locked TEA CO2 laser
Authors: Megie G. , Menzies R. T.
Published: February 2003

Tunable single-longitudinal-mode operation of a transversely excited atmospheric (TEA) CO2 laser has been achieved using an injection technique with a cw waveguide laser as the master oscillator. Tunability in excess of 300 MHz from the CO2 line center is reported for various CO2 lines. A high resolution spectrum of an ozone absorption feature has been recorded using this technique.
An intense pulsed magnetically insulated deuteron source
Authors: Endo Gregory , Robertson Scott
Published: February 2003

We have constructed a magnetically insulated ion source in which deuterons are extracted from plasma generated by a deuterated titanium washer located within the field excluding anode. Peak beam parameters are 0.8 A/cm2 at 140 kV for 0.4 μsec with a 14-mm anode-cathode gap. Faraday cup measurements show significantly fewer impurities in the deuteron beam than in proton beams extracted from surface flashover plasma.
Determination of the interface states in GaAs MOS diodes by deep-level transient spectroscopy
Authors: Yamasaki Kimiyoshi , Sugano Takuo
Published: February 2003

The capture cross sections and density-energy distribution of the trap states at the interface between GaAs epitaxial layers and oxide films grown by anodization in oxygen plasma have been determined by deep-level transient spectroscopy (DLTS). The capture cross sections are of the order of 10−12–10−13 cm2. The state density in the energy space range from 1×1013 to 3×1013 cm−2 eV−1. It has a peak 0.43 eV below the conduction band edge, but increases again near the valence band edge. The existence of traps in the oxide is also suggested. The activation energies of the emission rates determined by constant-capacitance DLTS with a small pulse voltage are in good agreement with the surface potentials, and no particular band structure at the interface, such as an interface band, has been found.
Absorption studies at 193 nm in e-beam excited xenon
Authors: Duzy C. , Boness M. J. W.
Published: February 2003

This study was undertaken in order to determine whether the observed premature 172-nm laser pulse termination in pure xenon was caused by medium absorption. The absorption was measured by probing the e-beam excited xenon with an ArF (193 nm) laser. Analysis of the results indicates that premature pulse termination cannot be explained entirely by the observed medium absorption.
Stabilization of aging-induced self-pulsations and the elimination of an initial temporally saturable mode of degradation in (Al,Ga)As lasers by means of facet coatings
Authors: Nash F. R. , Hartman R. L. , Paoli T. L. , Dixon R. W.
Published: February 2003

We demonstrate that half-wavelength facet coatings of Al2O3 can arrest the growth of pulsations in the output intensity of (Al,Ga)As double-heterostructure lasers during cw aging in a 70 °C dry nitrogen ambient while also eliminating an initial mode of degradation. These concurrent effects of the coatings suggest a common origin for the aging-induced pulsations and the initial degradation and also support a recently proposed model for the origins of pulsations.
Thin film MOSFET’s fabricated in laser-annealed polycrystalline silicon
Authors: Lee K. F. , Gibbons J. F. , Saraswat K. C. , Kamins T. I.
Published: February 2003

Both depletion- and enhancement-mode MOSFET’s have been fabricated with the active transistor channels in laser-annealed polycrystalline-silicon films. A dose of 3×1012 31P/cm2 was implanted at 100 keV into 0.5-μm-thick poly-silicon films for the depletion-mode device, and a dose of 3×1011 11B/cm2 was used for the enhancement-mode device. The transistors fabricated in the poly-silicon films show electrical characteristics comparable to those of devices in single-crystal silicon. In the depletion-mode device, an electron mobility of ∼450 cm2/Vsec was obtained, and approximately 80% of the phosphorus was electrically active. The surface mobility of electrons was about 340 cm2/V sec in the enhancement-mode device, and a threshold voltage of approximately 2.5 V was obtained.
Current-field characteristics of oxides grown from polycrystalline silicon
Authors: Hu Chenming , Shum Ying , Klein Tom , Lucero Elroy
Published: February 2003

A new technique determined the J-E characteristics of silicon dioxide grown from polycrystalline silicon with greatly improved sensitivity. More importantly, the current density was measured over a 10-decade range without the problem of current drift or uncertainty about the field at the cathode surface due to charge trapping in the oxide. The apparent barrier height decreased with increasing electric field as if the barrier lowering was due to field enhancement at surface asperities of about 500 Å in size. The technique is applicable to other dielectrics where charge trapping presents difficulties to J-E measurements.
Molecular beam epitaxial growth of low-resistivity ZnSe films
Authors: Yao Takafumi , Makita Yunosuke , Maekawa Shigeru
Published: February 2003

Single-crystalline films of low-resistivity ZnSe have been successfully grown by molecular beam epitaxy (MBE). The film shows good crystallinity, having a smooth and flat surface as revealed by RHEED and SEM investigations. The resistivity of as-grown MBE ZnSe is low (typically ∼1 Ω cm) and the mobility of the film is relatively high (typically ∼300 cm2/V sec) at room temperature. The concentrations of the residual electrically active donor and acceptor centers are ND =8×1016 cm−3 and NA=6×1016 cm−3, respectively. The strong blue band-edge photoluminescence peak is observed even at room temperature, and the luminescence intensity at longer wavelength is very weak.
The photon avalanche: A new phenomenon in Pr3+-based infrared quantum counters
Authors: Chivian Jay S. , Case W. E. , Eden D. D.
Published: February 2003

Studies of laser-pumped Pr3+ infrared quantum counters have led to the discovery of a new photon avalanche region, occurring when pump flux exceeds a certain critical value. Infrared output near 4.5 μm is associated with the large visible output, and pump power is strongly absorbed. Critical pump power density is in the range 1.2–12.2 W/cm2.
Kinetics and fusion laser potential for the terbium chloride–aluminum chloride vapor complex
Authors: Jacobs Ralph R. , Krupke William F.
Published: February 2003

Fluorescence responses of the Tb3+ : 5D3 and 5D4 metastable levels are presented for the terbium chloride–aluminum chloride vapor complex excited by pulsed KrF laser radiation. Assuming unit quantum yield, excited-state densities as high as 3×1016 cm−3 (10 J/l) are inferred for the experimental conditions and maintained for times ≳10 μs.
A high-power CO2 waveguide laser
Authors: Carter G. M. , Marcus S.
Published: February 2003

A CO2 waveguide laser from which 39.5 W (51 W/m) has been obtained is described. These values are greater than any previously reported. Data on the temperature dependence of the output power are presented and discussed. An analysis was performed from which the small-signal gain (0.22 cm−1) and saturation power (35 W) at conditions of maximum power output were obtained. It is shown that the assumption of distributed loss gives a better fit to the observed laser output than does that of concentrated loss at the mirrors.
Chemically pumped iodine laser
Authors: Richardson R. J. , Wiswall C. E.
Published: February 2003

A chemically pumped iodine-atom laser is described based on electronic energy transfer to atomic iodine from chemically generated O2(1Δ). The total extracted power (10 W) is approximately 3% of the power contained in the O2(1Δ) flow.
Threshold energies for impact ionization by electrons and holes in InP
Authors: Pearsall T. P.
Published: February 2003

The threshold conditions for impact ionization in InP at 300 K have been calculated from the electronic band structure along the three major symmetry axes. These calculations show that conditions for electron-initiated impact ionization in InP are much more favorable than in GaAs.
Nucleation-controlled thin-film interactions: Some silicides
Authors: Anderson R. , Baglin J. , Dempsey J. , Hammer W. , d’Heurle F. , Petersson S.
Published: February 2003

Silicides formed by the interaction of a metal thin film with a single-crystal silicon substrate usually grow in layers according to diffusion- or reaction-controlled kinetics. The mechanism of the formation of five silicides, IrSi3, Rh4Si5, Hf Si2, NiSi2, and PdSi, share common aspects which set them categorically apart from IrSi1.75, RhSi, HfSi, NiSi, and Pd2Si, which form in the usual way. It is proposed that the nucleation process of IrSi3, Rh4Si5, HfSi2, NiSi2, and PdSi results from the respective small driving forces and the ensuing importance of usually negligible stress and/or surface effects.
Laser action at 3577 Å in proton-beam-pumped Ar-N2 mixtures
Authors: Wiley L. G. , Hammer D. A. , McFarlane R. A.
Published: February 2003

Laser action at 3577 Å has been achieved in argon/nitrogen mixtures of 400–1140 Torr total pressure by use of an intense proton beam from a magnetically insulated diode. The threshold for laser action in 700 Torr of 75% Ar/25% N2 was ∼1.3 MW/cm3 of deposited proton beam power. Laser power increased nearly four orders of magnitude as the deposited energy was raised to 15 times the threshold value. Amplified spontaneous emission increased rapidly with a deposited proton power of ≳16 MW/cm3. A maximum laser intensity of 450 kW/cm2 (1.1 mJ for 20 nsec FWHM with a 0.12-cm2 area) was obtained, without optimization of the output coupling mirror, in 25% N2 mixtures at 1140 Torr total pressure.
High-speed cutoff modulator using a Ti-diffused LiNbO3 channel waveguide
Authors: Neyer A. , Sohler W.
Published: February 2003

A high-speed intensity modulator has been fabricated taking advantage of the dependence of waveguide cutoff on its index of refraction. The modulator consists essentially of a 2-μm-wide 3.2-mm-long Ti-diffused channel waveguide in y-cut LiNbO3. By controlling the propagation cutoff through the electro-optic effect, an intensity modulation is obtained. The potential bandwidth, optical insertion loss, and specific energy at 0.63 μm are 5.3 GHz, 11 dB, and 230 μW/MHz, respectively. A brief analysis of modulator operation is given based on coupled-mode theory.
MIS solar cells with back surface fields
Authors: Tarr N. G. , Pulfrey D. L. , Iles P. A.
Published: February 2003

Al-SiOx-pSi MIS solar cells have been fabricated on 10-Ω cm substrates both with and without back surface fields. The back-surface-field structure has been found to significantly enhance the open-circuit voltage of these cells, and Voc values in excess of 580 mV have been recorded at photocurrent densities of 300 A m−2. These results provide further evidence that MIS diodes can be produced in which the dark current is dominated by minority-carrier flows.
Face dependence of the spin polarization of photoelectrons from NEA GaAs (100) and (110)
Authors: Pierce D. T. , Wang G. C. , Celotta R. J.
Published: February 2003

We present measurements of the spin polarization P of photoelectrons from negative electron affinity (NEA) GaAs (100) and find P=43% at a photon energy of 1.57 eV. This contrasts with a maximum P=21% measured by Erbudak and Reihl for NEA GaAs (110), which led them to conclude that NEA and high P exclude each other. This difference in P is important for sources of polarized electrons employing photoemission from GaAs. We suggest that the origin of this difference may be connected with differences in the photoelectron emission process at the two faces, as calculated by Burt and Inkson.
Cellular structure and silicide formation in laser-irradiated metal-silicon systems
Authors: van Gurp G. J. , Eggermont G. E. J. , Tamminga Y. , Stacy W. T. , Gijsbers J. R. M.
Published: February 2003

Laser irradiation of thin Co, Mo, and Pd films on single-crystalline silicon using Q-switched Nd-YAG laser pulses was shown by He backscattering to result in deep metal penetration into the Si. Evidence of the silicide formation was obtained by x-ray diffraction. Transmission electron microscopy showed the simultaneous occurrence of two types of cells with metal-rich walls: small cells of about 0.1-μm diameter, attributed to rapid solidification from a supercooled melt, and larger cells of about 1-μm diameter, attributed to convection in the melt (Bénard cells).
Edge-bonded surface-acoustic-wave transducer array
Authors: Tuan H. C. , Kino G. S. , Khuri-Yakub B. T. , Selfridge A. R.
Published: February 2003

A new type of transducer array has been designed and built for imaging surface defects in metals such as aluminum. The array is formed by edge bonding a piece of piezoelectric material to a substrate of the same material as the sample to be tested. The individual elements in the array are formed by photolithography, and each element acts as an edge-bonded surface wave transducer. The array has 32 elements resonant at a center frequency of 3.1 MHz with a round trip 6-dB bandwidth of 65%. Each element has a two-way insertion loss of 14 dB and a ± ° 3-dB acceptance angle. Because of the good acoustic impedance match between the piezoelectric material and the substrate material, the array does not need to be slotted. Electrical isolation between individual elements is achieved by depositing ground strips between the elements.
Photoluminescent characterization of GaAs solar cells
Authors: Pettit G. D. , Woodall J. M. , Hovel H. J.
Published: February 2003

Photoluminescence excitation measurements are shown to accurately determine the spectral response of Ga1−xAlxAs-GaAs heterojunction solar cells. The technique is applicable to as-grown structures prior to processing into final devices and can also be used to study postgrowth techniques designed to enhance the spectral response of such devices. The measurements indicate that some surface recombination passivation is obtained with anodization.