bluuebunny/crossref_metadata_2025 huggingface dataset:
Microsecond operation of a general purpose pulsed proton gun
Authors: Humphries S. , Kuswa G. W.
Published: February 2003

A magnetically insulated pulsed proton gun is described that provides an extracted parallel beam of annular cross section for microsecond pulse lengths. In initial tests, time-averaged currents of 5 kA and current densities of 50 A/cm2 were achieved with ≲200 kV voltage. The behavior of the gun appears to be determined by instabilities of the cathode electron cloud growing over time scales of the order of 0.5 msec to give ion current-density enhancements greater than a factor of 50 above the Child-Langmuir limit.
Semiconductor laser with integral light intensity detector
Authors: Scifres D. R. , Stutius W.
Published: February 2003

An integrated Si Schottky-barrier detector for the output power stabilization of a GaAs/GaAlAs DH laser mounted on a Si heat sink is described. The signal emitted from the rear laser mirror and detected by the integral Schottky diode was used to stabilize the laser output power to within ∼1% over a 32 °C temperature range, thus eliminating the need for mounting fibers to or aligning bulky discrete detectors with the rear laser mirror.
Coupling-length adjustment for an optical directional coupler as a 2×2 switch
Authors: Mikami Osamu , Zembutsu Sakae
Published: February 2003

A novel method for realizing the desired light coupling of an optical directional coupler for 2×2 switching is presented. This method consists of loading a high-index film on one of the waveguides and reducing the light coupling to zero in the undesired coupling region. The operation principle was experimentally examined using Ti-diffused LiNbO3 waveguides and Se-S–based chalcogenide glass film. The effective coupling length for the TE mode could be changed from 0 to 3L0 (L0 : 0-dB coupling length) by trimming the high-index strip.
Three-dimensional heat-flow effects in photoacoustic spectroscopy of solids
Authors: Quimby R. S. , Yen W. M.
Published: February 2003

All theories of the photoacoustic effect in solids to date have been one dimensional, ignoring lateral heat transport to the cell walls. By studying the dependence of the photoacoustic signal on the position of focused light on the sample’s surface, we have demonstrated experimentally that a three-dimensional heat-flow analysis is required in some cases, especially at low chopping frequencies. These results have implications for techniques where one measures the photoacoustic signal as a function of chopping frequency, such as the depth profiling of layered samples.
Electron bombardment effect on the breakdown voltage of Zener diodes
Authors: Tomimasu T.
Published: February 2003

The nature of electron irradiation-induced changes in the avalanche breakdown voltage has been investigated for Zener diodes with breakdown voltages from 5.6 to 25.5 V. Their breakdown-voltage change is proportional to the irradiation electron fluence and inversely proportional to the impurity gradient in the linearly graded silicon p-n junction.
Fabrication on a laboratory scale and mechanical properties of Cu-Nb-Sn multifilamentary superconducting composite wires produced by cold powder metallurgy processing
Authors: Flükiger R. , Akihama R. , Foner S. , McNiff E. J. , Schwartz B. B.
Published: February 2003

Superconducting Cu-Nb-Sn multifilamentary composites are fabricated inexpensively on a laboratory scale. Small (40 μm) particles of Cu and Nb are compacted, placed in a suitable external jacket for containment, then elongated at room temperature to form a multifilamentary circular wire. Processing yields a multifilamentary Cu-Nb-Sn superconductor with high overall critical current densities Jc at high magnetic fields. Measurements of the mechanical properties show no degradation of Jc for strains greater than 1% for composite made with a large areal reduction ratio.
An ultra-low-noise tunnel junction dc SQUID
Authors: Ketchen Mark B. , Voss Richard F.
Published: February 2003

The design, fabrication, and noise properties of an ultra-low-noise tunnel junction dc SQUID (superconducting quantum interference device) are presented. The two resistively shunted Pb-alloy tunnel junctions are each 3.6 μm diam. The SQUID has an inductance L of ≈11 pH, a critical current per junction, I0 of ≈100 μA, and a resistance per shunt R of ≈2 Ω. At 2.3 K, eI0R≈kBT, and simple theory predicts that the minimum intrinsic energy sensitivity should be ≈2h. The actual minimum value of the measured high-frequency (70 kHz) flux noise at 4.2 K is φn=1.3×10−7φ0 Hz−1/2. This corresponds to an intrinsic energy sensitivity, φ2n/2L, of 3.2×10−33 J Hz−1 or 5h. Lowering the bath temperature to 1.8 K gave no improvement in performance.
Small changes in work function of the TiC(001) surface with chemisorption of O2 and H2O
Authors: Oshima C. , Tanaka T. , Aono M. , Nishitani R. , Kawai S. , Yajima F.
Published: February 2003

Changes in work function of the TiC (001) surface have been measured against O2 and H2O exposure by using photoelectron spectroscopy. The sticking rates are about 1/100 of those for elemental Ti-metal substrate. In the case of oxygen exposure, the work function increases monotonically from 3.8 to 4.2 eV, whereas for H2O a maximum value of work function occurs at an exposure of ∼300L, and its value finally reaches 4.5 eV.
Optical synchrotron-Čerenkov radiation
Authors: Rynne T. M. , Erber T.
Published: February 2003

Synchrotron-Čerenkov radiation can significantly alter optical emission in the vicinity of the Čerenkov threshold. A convenient illustration is provided by 20-MeV electrons passing through ethene gas in a 5-kG field. For ethene densities of the order of 0.5. gm/l, or about 40% STP, the experimentally observable intensity of green light (ω∼2.4 eV) is expected to be amplified by five orders of magnitude over the levels predicted by a simple superposition of synchrotron and Čerenkov radiation.
Impedance-match experiments using laser-driven shock waves
Authors: Veeser L. R. , Solem J. C. , Lieber A. J.
Published: February 2003

A high-energy laser pulse has been used to drive a shock wave into a foil target. Pressures of 0.3 TPa in aluminum and 0.6 TPa in a gold overlay were inferred from simultaneous measurements of the shock velocities. The techniques will be useful in determining high-pressure equation-of-state parameters for a wide variety of materials.
Room temperature instability of electron induced defects in n-type silicon containing germanium
Authors: Evwaraye A. O.
Published: February 2003

n-type silicon containing germanium was irradiated with a 1.5-MeV electron beam at 300 K. An electron trap E3(Ec−0.35 eV), not observed in n-type silicon without germanium, is unstable at room temperature. Annealing studies show that the annealing kinetics is first order; an activation energy for thermal anneal of 0.63 eV and a frequency factor of 2.58×106 sec−1 were estimated. It is suggested that the E3 complex anneals by migrating to sinks where it is modified. This migration is greatly enhanced by changing the charge state of the defect. Reirradiation of E3-annealed-out devices does not produce the E3 defect state. This supports the suggestion that the complex does not anneal by dissociation but by migration to sinks where it is modified and tied up.
Analysis of deterioration in In solder for GaAlAs DH lasers
Authors: Fujiwara K. , Imai H. , Fujiwara T. , Hori K. , Takusagawa M.
Published: February 2003

The deterioration of In solder associated with the degradation of GaAlAs DH lasers has been investigated. The deterioration of In solder is found to be caused by the diffusion of Au atoms into In solder. The increase in the thermal resistance of DH lasers is observed for the storage test. The increase in the thermal resistance is caused by the formation of the intermetallics between In and Au, which is thermally activated.
Pulsed electron beam induced recrystallization and damage in GaAs
Authors: Tandon J. L. , Golecki I. , Nicolet M-A. , Sadana D. K. , Washburn J.
Published: February 2003

Single-pulse electron-beam irradiations of 300-keV 1015Kr+/cm2 or 300-keV 3×1012 Se+/cm2 implanted layers in unencapsulated 〈100〉 GaAs are studied as a function of the electron beam fluence. The electron beam pulse had a mean electron energy of ≃20 keV and a time duration of ?10−7 s. Analyses by means of MeV He+ channeling and TEM show the existence of narrow fluence window (0.4–0.7 J/cm2) within which amorphous layers can be sucessfully recrystallized, presumably in the liquid phase regime. Too high a fluence produces extensive deep damage and loss of As.
High-resolution optoacoustic spectroscopy of rare-earth oxide powders
Authors: Tam A. C. , Patel C. K. N.
Published: February 2003

We report high-resolution absorption spectroscopy of powdered microsamples using a pulsed laser and a gated optoacoustic detection technique. Our method is simple, sensitive, and easily adaptable for cryogenic cooling of the sample. Quantitative data for Ho2O3, Dy2O3, and Er2O3 powdered crystals are obtained, and identification and analysis of the observed spectral lines are given for Dy2O3 and Er2O3.
Optical bistability at a nonlinear interface
Authors: Smith P. W. , Hermann J.-P. , Tomlinson W. J. , Maloney P. J.
Published: February 2003

Under suitable conditions, the boundary between a linear and a nonlinear (Kerr effect) medium should have a reflection coefficient which exhibits hysteresis as a function of optical intensity. We present the first experimental evidence of this effect. Experiments were performed using ∼1-ns ruby laser pulses incident on a glass-CS2 boundary.
Josephson effect in Nb nanobridges
Authors: Laibowitz R. B. , Broers A. N. , Yeh J. T. C. , Viggiano J. M.
Published: February 2003

High-resolution electron-beam lithographic techniques have been used in the fabrication of thin ultranarrow superconducting Nb stripes. The ac Josephson effect in the form of microwave-induced current steps has been observed in a series of samples in which the length has been varied from about 1 to 0.1 μm. Studies of the phase slip centers in these samples have led to an estimate for the quasiparticle diffusion length and inelastic scattering time of about 90 nm and 13 ps, respectively.
Electron dissociative attachment rate constants for F2 and NF3 at 300 and 500 °K
Authors: Trainor Daniel W. , Jacob J. H.
Published: February 2003

Electron attachment to F2 and NF3 has been studied in an electron-beam-controlled gas-discharge apparatus over a range of E/P (2–10 kV/cm atm). These experiments were performed in gas mixtures containing small amounts of the halide molecules (≲1%) in an atmosphere of N2 which was included to control the average electron energy. We obtained values for the rate constants for dissociative attachment to F2 and NF3 as a function of mixture temperature at 300 and 500 °K and applied electric field. These results compare favorably with the rate constants deduced from the absolute cross section for these compounds reported by Chantry.
Improving the radiative yield of GaAs by laser annealing
Authors: Rostworowski J. A. , Parsons R. R. , Hutcheon D. G.
Published: February 2003

We have measured the photoluminescence properties of laser-annealed single-crystal GaAs. The quantum efficiency of the band-edge emission at liquid helium temperatures was increased by 3 orders of magnitude after a single 10−3-s pulse of ruby laser light. This increase in radiative efficiency is thought to be due to dissociation of Si-donor-Ga-vacancy complexes, which is expected to decrease nonradiative processes and possibly increase radiative centers. A theoretical prediction of the temperature distribution at the end of the laser pulse was performed.
Observation of semiconductor-semimetal transition in InAs-GaSb superlattices
Authors: Chang L. L. , Kawai N. , Sai-Halasz G. A. , Ludeke R. , Esaki L.
Published: February 2003

The semiconductor-semimetal transition in InAs-GaSb superlattices is observed at a layer thickness in the vicinity of 100 Å. The transition manifests itself in an increase in the measured carrier concentration as a result of electron transfer from GaSb to InAs when ground subbands of electrons and heavy holes cross each other. Shubnikov-de Haas measurements confirm the carrier enhancement in the semimetallic state.
High-current A-15 microcomposite materials
Authors: Borman R. , Freyhardt H. C. , Bergmann H.
Published: February 2003

Powder metallurgy is used as an alternative process to produce Nb3Sn and V3Ga composite superconductors with large critical transport currents in magnetic fields above 15 T. Whereas for a Cu–30 wt.%Nb +Sn composite the overall current density Jc amounts to 1.0×108 A/m2 at 16 T, values in excess of 4×108 A/m2 (16 T) are observed for Cu–30 wt.% V+Ga composites.
Operating characteristics of a closed cycle flow rare gas halide laser
Authors: Miller J. L. , Dickie J. , Davin J. , Swingle J. , Kan T.
Published: February 2003

A UV preionized, high-purity construction, closed-cycle-flow rare-gas-halide laser has been constructed to study laser characteristics at high pulse repetition frequency and closed cycle behavior of the laser chemistry. Operating characteristics of the laser with ArF, KrF, XeF, and XeCl have been obtained. The XeCl laser has demonstrated the best performance, yielding a maximum average power of 45 W at 600 Hz and greater than 35 W at 500 Hz for 1 h.
Laser photodeposition of metal films with microscopic features
Authors: Deutsch T. F. , Ehrlich D. J. , Osgood R. M.
Published: February 2003

Metal deposits with features smaller than 2 μm have been produced by the uv laser-induced photodissociation of organometallic compounds. Such laser-induced heterogeneous photochemical processes may have application in several areas of microelectronics including metallization, etching, and growth of semiconductor films.
A new type of amorphous silicon photovoltaic cell generating more than 2.0 V
Authors: Hamakawa Y. , Okamoto H. , Nitta Y.
Published: February 2003

A new type of plasma-deposited amorphous silicon photovoltaic cell having a horizontally multilayered p-i-n unit-cell structure has been developed. The open-circuit voltage Voc is nearly proportional to the number of repetitions of the p-i-n unit cell. Almost-constant energy-conversion efficiencies of around 4% have been obtained with Voc ranging from 0.6 to 2.4 V by applying a simple optimum design rule to the cell-construction parameters.
Measurements of the rectifying barrier heights of the various iridium silicides with n-Si
Authors: de Sousa Pires J. , Ali P. , Crowder B. , d’Heurle F. , Petersson S. , Stolt L. , Tove P. A.
Published: February 2003

The barrier height of Schottky diodes formed with 〈111〉 and 〈100〉 n-type silicon substrates and Ir, IrSi, IrSi1.75, and IrSi3 have been determined by means of photoresponse, capacitance, and forward I/V measurements. In all cases the barrier height values are quite high, in excess of 0.85 eV. For Ir, IrSi, and IrSi1.75 the values obtained agree with values previously derived from forward I/V curves.
Two-dimensional average concentration measurements in a jet flow by Raman scattering
Authors: Webber Bruce F. , Long Marshall B. , Chang Richard K.
Published: February 2003

A multipass cell arrangement and a low-light-level television camera were used to obtain a simultaneous digitized two-dimensional concentration profile of CH4 flowing from an axisymmetric jet by measuring the spontaneous Raman radiation. Because the Raman technique is species selective, the concentration profile of the N2 contained in the surrounding gas (air) was also determined for CH4 and SF6 jets under the same conditions. Comparison is made with the concentration profiles determined by Mie scattering in seeded jets.
Single-mode fiber multiterminal star directional coupler
Authors: Sheem S. K. , Giallorenzi T. G.
Published: February 2003

We report the first single-mode multiterminal star coupler in which fibers are grouped into sets of three fibers. The three fibers in each set were than braided over some length before one or more of the fibers of each set are interchanged with their counterparts in other sets. We utilized the encapsulated etching technique reported earlier to overcome the peculiar geometric problems associated with single-mode fibers. Excellent output uniformity and very low throughput loss have been achieved in these devices because of our new designs. We also present coupled-mode theoretical analysis which can be used to describe these new single-mode star couplers.
Annihilation of frozen-in point defects in GaP by thermal and recombination-induced processes
Authors: Werkhoven C. , Hengst J. H. T. , van Opdorp C.
Published: February 2003

Minority-carrier-lifetime measurements on heat-treated rapidly cooled LEC-grown GaP reveal strong nonradiative recombination at frozen-in point defects. Cathodoluminescence line scan studies show that during slow cooling the point defects introduced during heating are removed by diffusion to dislocations and microdefects; the intensity of the resulting luminescence halos around the dislocations depends on heat treatment, due to variations in minority-carrier lifetime. Alternatively, frozen-in point defects can also be annihilated by photon excitation and by electron-beam excitation. In these cases, phonons liberated during nonradiative recombination at the point defects excite defect motions which result in annihilation reactions; these are probably recombination reactions between Frenkel pairs.
Large-angle acoustic-beam steering in acoustically anisotropic crystal
Authors: Lean E. G. , Chen W. H.
Published: February 2003

We have demonstrated a unique scheme for electronically steering an acoustic beam over an angle large than 70° in a TeO2 crystal. The idea is based on the principle that the acoustic energy flow direction is always normal to the slowness curve in an acoustically anisotropic crystal. In the plane normal to the c axis of a TeO2 crystal and around the (110) axis, the shear wave acoustical energy flow directions can have a swing of more than 70° [from the (110) axis] by changing the wave-vector direction only 3° from the (110) axis. Using a grating to diffract a shear wave propagation direction around the (110) axis, we have observed the wide-angle acoustic-beam steering effect by a laser probe.
Positive-ion recovery scheme based on magnetic blocking of electrons
Authors: Stirling W. L. , Kim J. , Haselton H. H. , Barber G. C. , Davis R. C. , Dagenhart W. K. , Gardner W. L. , Ponte N. S. , Tsai C. C. , Whealton J. H. , Wright R. E.
Published: February 2003

A method is described for making positive-ion-based neutral-beam injection viable at energies of ≲100 keV per nucleon by recovering the energy of residual charged particles as electrical energy. The concept of transverse magnetic field blocking of electrons has been shown to be successful, and preliminary experimental results are presented.
Time-dependent voltage measurement of pulsating AlxGa1−xAs double-heterostructure lasers
Authors: van der Ziel J. P.
Published: February 2003

The optical pulsations in the output of semiconductor lasers are accompanied by a time variation of the diode voltage. During the optical pulse the voltage decreases by ≈2.5 mV, corresponding to a decrease in carrier population. In the interval between pulses the voltage recovers exponentialy with a 1.3±0.2-nsec time constant to its prepulse value as a result of carrier injection into the active region.
Sulfur incorporation and thickness variation in vapor-phase-epitaxial GaAs layers for FET’s
Authors: Vidimari F.
Published: February 2003

Significant nonuniformities in thickness and carrier concentration were observed in thin GaAs layers grown by VPE on semi-insulating substrates placed parallel to the gas flow in a flat temperature deposition zone. The existence of a boundary layer was taken into account to explain the variation of the growth rate along the flow direction. Since sulfur incorporation showed a linear increasing dependence on the growth rate, it was also influenced by the same mechanism. A modified reactor geometry was employed to improve thickness and doping uniformity up to an overall variation of ±2.5 and ±4%, respectively, over a useful area of about 4 cm2.
Electron-beam delineation of Pb1−xSnxTe films on BaF2
Authors: Beck W. A. , Buchner S. P. , Byer N. E. , Sun T. S.
Published: February 2003

We find that predeposition electron irradiation of the surface of BaF2 dramatically alters the sticking coefficient for Pb1−xSnxTe and hence can be used to define MBE-grown films. Auger electron spectroscopy and low-energy-diffraction results indicate that room-temperature e-beam irradiation of the BaF2 produces a disordered barium oxide surface layer. Upon heating to 450°C, the oxide interacts with residual gases in the MBE vacuum system to form a carbon layer approximately one monolayer in thickness. This surface presents a low sticking coefficient to the Pb1−xSnxTe. On the other hand, irradiation at 450 °C desorbs the carbon and oxide layers and restores a high sticking coefficient.
Back surface gettering and Cr out-diffusion in VPE GaAs layers
Authors: Magee T. J. , Peng J. , Hong J. D. , Evans C. A. , Deline V. R. , Malbon R. M.
Published: February 2003

Mechanical back surface damage gettering has been investigated for improving the quality of GaAs substrates and VPE layers on semi-insulating GaAs. It has been shown that the pregettering of substrates reduces the interfacial defect density and alters the level of Cr out-diffusion into the VPE layer during growth. At a postdeposition anneal temperature of 800 °C, Cr out-diffusion into the VPE layer is relatively suppressed in the pregettered substrate, while the ungettered sample shows larger concentrations of Cr within the epitaxial layer.
Observation of i
n s
i
t
u annealing in hot ion-implantation of nitrogen into AlxGa1−xAs (x=0.53)
Authors: Makita Yunosuke , Nojiri Hidetoshi , Tsurushima Toshio , Tanoue Hisao , Shimada Jun-ichi
Published: February 2003

Photoluminescence measurements were carried out for indirect band-gap Al0.53Ga0.47As crystals in which nitrogen ions were implanted at various elevated temperatures. It was found that samples implanted at temperatures higher than 525 °C exhibit characteristic emission bands associated with the nitrogen isoelectronic trap without any annealing treatments. This observation apparently shows that the substitutional procedure takes place simultaneously during implantation. We have also found that the substitutional mechanism is closely related with the formation of arsenic vacancies through which implanted atoms are located to the host arsenic sites.
Spectrally selective surfaces of Ni-pigmented anodic Al2O3
Authors: Granqvist C. G. , Andersson Å. , Hunderi O.
Published: February 2003

Ni pigmentation of anodic Al2O3 is obtained by electrolytic coloration. Durable coatings with good spectral selectivity (a/e≃8) are produced. Scanning electron microscopy, Auger depth profiling, and atomic absorption analysis lead to the formulation of a detailed structural model, its most essential feature being a thin layer comprising a mixture of Ni and Al2O3 located near the bottom of the anodic film. Experimental spectral reflectance data agree well with computer calculations, provided the optical properties of the metal-insulator layer are described with the Bruggeman effective medium theory.
Self-aligned structure InGaAsP/InP DH lasers
Authors: Nishi H. , Yano M. , Nishitani Y. , Akita Y. , Takusagawa M.
Published: February 2003

Self-aligned structure InGaAsP/InP DH lasers with emission wavelengths near 1.3 μm are studied. A cw threshold of about 100 mA is obtained in these lasers with cavity lengths of about 300 μm at a heat sink temperature of 25 °C. Light output increases linearly with current for outputs of 10 mW per facet and no kinks appear. Fundamental-transverse and single-longitudinal mode oscillation, and stable operation of fundamental-transverse mode against injection current, are achieved. A cw operation up to 72 °C is obtained with a laser.
A geodesic optical waveguide lens fabricated by anisotropic etching
Authors: Naumaan A. , Boyd J. T.
Published: February 2003

A geodesic optical waveguide lens which has been fabricated by anisotropic etching on a silicon substrate is reported. Reflow of phosphosilicate glass provides considerable rounding at sharp edges to reduce scattering. Successful operation of the waveguide lens is illustrated by observation of guided beam trajectories traversing different portions of the lens and converginng to a common point and by measurements of the focal-plane diffraction pattern. A beam width which is 1.7 times the diffraction-limited value for a f/15 lens is measured.
Long-wavelength stimulated emission via cascade laser action in Ho : YLF
Authors: Esterowitz L. , Eckardt R. C. , Allen R. E.
Published: February 2003

Two cascade laser schemes are demonstrated for Ho3+ in LiYF4. The first involves the 5S2, 5I5, and 5I7 manifolds with laser oscillation at 1.392 and 1.673 μm, and the second involves the 5S2, 5I5, and 5I6 manifolds with laser oscillations at 1.392 and 3.914 μm. The 3.9-μm transition is the longest-wavelength rare-earth laser achieved to date and further the system has attractive engineering practicality. The specificity of excitation inherent in the cascade approach is considered essential in overcoming the adverse multiphonon relaxation processes at long wavelengths.
Helmholtz resonance cells for pulsed dye laser-excited high resolution optoacoustic spectroscopy
Authors: Shaw Robert W.
Published: February 2003

The signal waveform observed in optoacoustic measurements is complex and highly dependent on sample for open-cavity cells and pulsed optical excitation. A Helmholtz resonator (HR) cell has been employed to reduce this dependence on sample and thus simplify signal processing. The cell background signal is likewise reduced with the HR cell. An optoacoustic (OA) spectrum of holmium oxide powder is presented to demonstrate the utility of this cell with pulsed dye laser excitation for acquistion of high resolution OA spectra of solids.
A new surface-acoustic-wave cut of quartz with orthogonal temperature-compensated propagation directions
Authors: O’Connell Robert M.
Published: February 2003

A theoretical study of the surface-acoustic-wave (SAW) properties of quartz has produced a new cut which is temperature compensated along two orthogonal directions. This new cut is attractive for use in reflection-grating devices such as the reflective array compressor (RAC), in which orthogonal propagation paths are required. Except for a small electromechanical power flow angle, the SAW properties along the two temperature-compensated directions are similar to those of x-propagating ST-cut quartz. Because the attractive propagation paths lie in the plane of a singly rotated crystal cut, it should be relatively easy and inexpensive to manufacture.
Niobium silicide formation induced by Ar-ion bombardment
Authors: Kanayama T. , Tanoue H. , Tsurushima T.
Published: February 2003

The effect of Ar-ion bombardment on evaporated–Nb-on-Si systems has been investigated with He backscattering and x-ray-diffraction measurements. High-dose bombardment with energetic Ar ions was found to induce intermixing between Nb and Si in the form of NbSi2. This effect has strong dependence on temperature during bombardment, although it cannot be explained as enhanced diffusion due to radiation damage or ion-beam heating.
Solar furnace annealing of amorphous Si layers
Authors: Lau S. S. , von Allmen M. , Golecki I. , Nicolet M-A. , Kennedy E. F. , Tseng W. F.
Published: February 2003

We demonstrate that a simple Al solar reflector can be used to induce solid-phase epitaxy of amorphous Si layers obtained either by ion-implantation or ion-deposition techniques. The annealing can be accomplished in air and takes a few seconds for a 1-cm2 sample area. For ion-implanted samples, the regrown layers are defectfree on 〈100〉 substrates, and contain microtwins on 〈111〉 substrates. For deposited layers on 〈100〉 substrates the degree of epitaxy is not as good as that obtained by furnace annealing (550 followed by 950 °C annealing).
Energy transfer between 5d electronic states of trivalent rare-earth ions
Authors: Yang K. H. , DeLuca J. A.
Published: February 2003

We have observed 5d-to-5d energy transfer from trivalent Tm to Nd in YF3 and LuF3 and Nd to Ce in YF3. In a YF3 : 5 mol% Tm : 1 mol% Nd sample, the probability of energy transfer from Tm3+ to Nd3+ was determined to be 0.94. The 5d-to-5d energy transfer has the possibility of broadening the optical pumping bands of the LiYF4 : Ce3+ laser and other laser systems involving the 5d14f n−1 to 4f n transition of trivalent rare-earth doped fluorides.
Pulse-shaped dependence of backscattered light from a KrF laser-produced plasma
Authors: Endoh A. , Watanabe S. , Miyazaki K. , Sato T. , Kashiwagi H.
Published: February 2003

Aluminum and carbon targets have been irradiated in vacuum using an uv-preionized KrF amplification system delivering up to 0.87 J in a 30-nsec pulse. A pulse-shaping technique has been employed to study the laser-plasma interaction at the irradiance level 1×1010 W/cm2. Energy reflectivities and backscattered pulse modifications have been measured for three typical laser pulse shapes. A typical pulse having two distinctive peaks with a 30-nsec interval were reflected from the plasma with its second peak strongly reduced.
Hollow-cathode excitation of ion laser transitions in noble-gas mixtures
Authors: Solanki R. , Latush E. L. , Gerstenberger F D. C. , Fairbank W. M. , Collins G.J.
Published: February 2003

Excitation of laser transitions in He-Kr, He-Ar, Ne-Xe, and He-Ne-Xe mixtures was investigated in hollow-cathode discharges. The dominant excitation mechanism of the noble-gas ions was found to be collisions of the second kind between the ground-state noble-gas ions and helium or neon metastables. Based on gain and absorption spectroscopy measurements, the cross section for this mechanism was estimated to be ⩾10−14 cm2. New laser transitions in noble-gas and copper ions are also reported.
Anomalous electrical and optical characteristics of GaAs/AlxGa1−xAs heterostructure materials
Authors: Wakefield B. , Stevenson J. L. , Redstall R. M. , Ambridge T.
Published: February 2003

GaAs/AlxGa1−xAs double-heterostructure layers grown by conventional LPE have been examined by three separate electrical and optical techniques. Some material has exhibited characteristics not previously detected in epilayers grown singly. Our central observation is that Ge-doped passive and active layers can have n-type conductivity within the heterostructure.
Photoconductive imaging using hydrogenated amorphous silicon film
Authors: Imamura Y. , Ataka S. , Takasaki Y. , Kusano C. , Hirai T. , Maruyama E.
Published: February 2003

Highly resistive hydrogenated amorphous-silicon film has been fabricated and examined as blocking-type photoconductive target of a vidicon-type image pickup tube. The results indicate that this novel silicon vidicon has many advantages over conventional ones.
Photothermal effect at TiO2 electrodes in a photoelectrochemical cell
Authors: Decker Franco , Julião J. F. , Abramovich M.
Published: February 2003

Anomalous photoresponse of n-TiO2 in a photoelectrochemical cell was previously observed to be induced by light of energy lower than the bandgap. This photoresponse was attributed to surface states at the TiO2-electrolyte interface. We studied this effect at stationary and rotating disk TiO2 electrodes and we show that the anomalous photoresponse is a thermal effect due to heating of the crystal surface by the illumination.
Differences in sodium transport in SiO2 films caused by ion and neutral-particle bombardment
Authors: McCaughan Daniel V. , White C. W. , Kushner R. A. , Simms D. L.
Published: February 2003

The transport of impurity atoms from the surface to the SiO2/Si interface of SiO2 films on silicon subjected to ion and neutral-particle bombardment has been found to depend critically on the charge state of the incident projectile. SiO2 films on silicon, intentionally contaminated with 22Na, have been bombarded by low-energy neutral N02 and Ar0, by N+2 and Ar+ ions, and by these ions with concurrent thermal electron flooding of the insulator surface. Neutral-particle bombardment in the energy range 500–2000 eV causes no measurable sodium transport to the SiO2/Si interface. Ion bombardment at the same energy and dose causes migration of much of the sodium away from the SiO2 surface to the interface. Ion bombardment in the presence of simultaneous electron flooding is an intermediate case, causing two orders of magnitude less sodium transport than ions alone, but resulting in at least two orders of magnitude more sodium transport than neutral-particle bombardment. These results suggest that neutral-atom sputtering or neutral-atom beam methods may be preferred techniques for insulator profile analysis to avoid problems associated with impurity transport, and neutral beams may be preferable to ion beams for sputter etching.
Photoluminescence of ArS, KrS, and XeS in rare-gas matrices
Authors: Taylor R. V. , Walker W. C.
Published: February 2003

The photoluminescence emission spectra and radiative lifetimes of the rare-gas sulfides ArS, KrS, and XeS in solid rare-gas matrices are presented. The emission is in the near infrared, and the lifetimes are of the order of several μs. Our emission spectra are compared with recent gas-phase emission spectra.
The orotron–A free-electron laser using the Smith-Purcell effect
Authors: Leavitt Richard P. , Wortman Donald E. , Morrison Clyde A.
Published: February 2003

A theory of operation of the orotron is described in which the electromagnetic field present in the open resonator of the device bunches the electron beam; this bunching leads to coherent oscillation. Theoretical results at 75 GHz are discussed.
Thermal emissivity of selective surfaces—New lower limits
Authors: Trotter D. M. , Sievers A. J.
Published: February 2003

Numerical calculations of the thermal emissivity ε of spectrally selective surfaces consisting of absorbing films on reflective metal substrates are reported. A physically realizable form for the absorption coefficient of the film α (ω), and a refractive index n (ω) derived from α (ω) via a Kramers-Kronig relation were used to obtain new lower limits for ε.
LPE growth of Hg0.60Cd0.40Te from Te-rich solution
Authors: Schmit Joseph L. , Bowers John E.
Published: February 2003

Hg0.60Cd0.40Te has been grown at atmospheric pressure using a liquid phase epitaxy (LPE) slider system. The compositions are uniform to within ±0.01 mole fraction across the layer and with depth into the layer except for a 3-μm-thick interdiffusion region. The layers are p type as grown with carrier concentration of 1017 cm−3 and are annealable to n type with a carrier concentration of 4×1015 cm−3.
Anomalous infrared absorptance of aluminum under pulsed 10.6-μm laser irradiation in vacuum
Authors: McKay J. A. , Schriempf J. T.
Published: February 2003

Above a distinct threshold laser flux of 70-MW/cm2 peak (for a pulse consisting of a 150-ns spike and a 1.8-μs tail), the calorimetrically measured effective absorptance of unpolished 3003 alloy aluminum increases abruptly to roughly 14%. While too high to be ascribed to ordinary metal infrared absorptance at any reasonable temperature, this value is typical of total-energy thermal coupling in air with air plasma ignition. We propose that this absorptance is in fact due to the ignition of a plasma in metal vapor produced by thermally isolated metal defects, rather than to a metal-dielectric transition.
Laser-alloyed stripe-geometry DH lasers
Authors: Salathé R. , Badertscher G. , Lüthy W. , Reinhart F. K. , Logan R. A.
Published: February 2003

Stripe-geometry contacts have been produced by focusing a Q-switched Nd : YAG laser with a cylindric lens on metallized (AlxGa1−xAs) DH lasers. The contact formation has been performed directly on the p-type AlGaAs cladding layer without a protecting gas ambient. The laser diodes fabricated from this material exhibited low threshold currents and have been operated cw at room temperature. The nearfield and spectral properties are comparable to diodes fabricated by conventional techniques.
Electrical and structural characteristics of laser-induced epitaxial layers in silicon
Authors: Young R. T. , Narayan J. , Wood R. F.
Published: February 2003

We have used pulsed-laser radiation to grow homoepitaxial p-n junctions in silicon. Doped amorphous silicon was deposited on (100) and (111) silicon substrates and annealed with a Q-switched ruby laser. By this technique, perfect epitaxial layers with good electrical characteristics and controlled dopant profiles can be achieved. The technique can potentially be competitive with or replace ion implantation for many semiconductor-device applications.
A silicon heterojunction transistor
Authors: Matsushita T. , Oh-uchi N. , Hayashi H. , Yamoto H.
Published: February 2003

SIPOS (Semi-insulating polycrystalline silicon) which is used as a surface passivation layer for highly reliable silicon devices constitutes a good heterojunction for silicon. P- or B-doped SIPOS has been used as the emitter material of a heterojunction transistor with the base and collector of silicon. An npn SIPOS-Si heterojunction transistor showing 50 times the current gain of an npn silicon homojunction transistor has been realized by high-temperature treatments in nitrogen and low-temperature annealing in hydrogen or forming gas.
The influence of plasma annealing on electrical properties of polycrystalline Si
Authors: Makino T. , Nakamura H.
Published: February 2003

Polycrystalline silicon doped with phosphorus and boron was prepared by low-temperature CVD and was annealed in a hydrogen/nitrogen plasma at 300 °C. The dopants were introduced by ion implantation and the concentration ranged from 2×1016 to 2×1019 cm−3. Plasma annealing decreased the poly-Si resistivity, which is significant at particular doping concentrations depending on density of localized states. The effect is due to reduction of deep localized states through hydrogenation and is canceled by additional annealing in nitrogen at 600 °C.
The importance of geometry, field, and temperature in tunneling and rectification behavior of point contact junctions of identical metals
Authors: Miskovsky N. M. , Shepherd S. J. , Cutler P. H. , Sullivan T. E. , Lucas A. A.
Published: February 2003

This letter presents new results on the tunneling and rectification characteristics of metal-whisker point-contact diodes. The model adopted here includes two new important effects, namely, the actual geometrical asymmetry of the electrodes and a temperature differential between tip and base. Calculations, for a point-contact junction of identical metals, confirm the feasibility of a rectification mechanism based solely on the geometrical asymmetry of the tip and base.
Bright green electroluminescence in thin-film ZnS : TbF3
Authors: Okamoto K. , Hamakawa Y.
Published: February 2003

A bright green electroluminescent (EL) thin-film device for a flat-type display has been developed. The device is constructed by a ZnS : TbF3 thin-film sandwiched between two semiconductive Y2O3 layers. A typical brightness of 200 fL and a power conversion efficiency of 4×10−4 W/W, values at least several times higher than reported elsewhere for green-color thin-film EL, are stably obtained at an excitation frequency of 5 kHz. This device is also capable of dc excitation with high efficiency (1×10−3 W/W) due to the existence of a semiconductive Y2O3 layer instead of an insulating layer. The semiconductive Y2O3 layer used in this device plays an important role in producing carriers in the ZnS active layer. Technical data on the characterization of the carrier injection mechanism and the device performance are presented and discussed.
Temperature-dependent absorption processes in the XeF laser
Authors: Champagne L. F.
Published: February 2003

Temperature-dependent absorption processes in neon/xenon/NF3 mixtures are reported. In pure neon plasmas there are two types of absorption present; a broad but weak band of absorption is observed, which increases with increasing temperature, and a strong narrow band of absorption is observed around 351 nm. Moderate heating reduces this absorption. Improved performance of the XeF laser at elevated temperature is primarily due to reduced absorption in the laser medium at 351 nm.
Enhancement of convolution voltage due to transverse drift of carriers in piezoelectric semiconductor SAW convolvers
Authors: Matsumoto Shigetaka
Published: February 2003

The enhancement of the convolution voltage of piezoelectric surface acoustic wave (SAW) convolvers due to the transverse drift of carriers is predicted theoretically. The theoretical prediction is qualitatively in agreement with the result of experiments using photoconductive CdS samples.
Photoluminescence of undoped (100) InP homoepitaxial films grown by molecular beam epitaxy
Authors: Kawamura Yuichi , Ikeda Mutsuo , Asahi Hajime , Okamoto Hiroshi
Published: February 2003

A comparative study is given of the photoluminescence properties between undoped (100) InP homoepitaxial MBE and LPE films and bulk crystals. All of the samples show two peaks; one is a near band-edge emission at 1.41 eV with a small shoulder and the other is at about 1.13 eV. It is shown that the MBE films have a near band-edge emission with intensity comparable with the LPE films, and exhibit a smaller amount of deep-level emission than the LPE films and bulk crystals.
Impurity and phonon scattering in layered structures
Authors: Hess K.
Published: February 2003

The scattering rates for the electron-impurity and the electron-phonon interactions in semiconductor multilayer heterojunction structures are calculated. It is found that phonon scattering is enhanced in such structures, whereas, impurity scattering can be strongly reduced at low temperatures as found experimentally.
Continuous room-temperature multiple-quantum-well AlxGa1−xAs-GaAs injection lasers grown by metalorganic chemical vapor deposition
Authors: Dupuis R. D. , Dapkus P. D. , Holonyak N. , Kolbas R. M.
Published: February 2003

Room-temperature (∼26 °C) continous operation of AlxGa1−xAs-GaAs multiple-quantum-well injection lasers has been achieved. These devices are grown by metalorganic chemical vapor deposition and employ active regions consisting of six GaAs quantum wells having a thickness Lz∼120 Å separated by five Al0.30Ga0.70As barriers also ∼120 Å thick. These laser diodes operate on LO-phonon-assisted confined-particle transitions and exhibit low threshold current densities (Jth∼1660 A/cm2) and high total external differential quantum efficiencies (ηext∼85%).
High-power switching with picosecond precision
Authors: Mourou G. , Knox W.
Published: February 2003

Up to 10 kV have been switched with Si and GaAs laser-activated switches. We show that in spite of the thermal instability shortcoming experienced in Si, quasi-dc bias operation can be utilized in a manner which relaxes stringent synchronization requirements. In the case of GaAs the thermal instability is less severe and up to 8 kV dc has been held off and efficiently switched. In both cases, a fast switching time of ∼40 ps is observed. This time is a combination of the laser pulse width, geometry bandwidth, and jitter time. Efficient switching action requires only a few tens of microjoules of laser energy. Electrical pulses ranging from subnanosecond to hundreds of nanoseconds duration have been readily generated.
Optically controllable millimeter wave phase shifter
Authors: DeFonzo A. P. , Lee Chi H. , Mak P. S.
Published: February 2003

We have demonstrated a new approach to controlling millimeter wave propagation with light. Phase shifts as high as 300°/cm of 94-GHz millimeter waves were observed accompanied by less than 1 dB insertion loss. A straightforward model was found to account in detail for the observed behavior.
Electromagnetic acoustic resonance in metals and alloys
Authors: Spencer E. G. , Schmidt P. H. , Sansalone F. J.
Published: February 2003

A technique has been developed for measuring the temperature dependence of elastic moduli of metals and alloys using electromagnetic excitation of acoustic resonance in small spheres polished optically smooth. A frequency swept marginal oscillator is used to generate and detect resonances without physical contact to the sample. Values of Cij are reproducible with accuracies of ∼1/104. Variations of ∼1/106 are detected using an oscillator mode which is phase locked to sample resonance. Measurements of C44 and (1/2)(C11−C12), from 300 to 4.2 K, on a 4.7-mm-diam. tungsten sphere are given to illustrate the technique.
Temperature-compensated PbTiO3 ceramics for surface acoustic wave applications
Authors: Ito Yukio , Takeuchi Hiroshi , Jyomura Shigeru , Nagatsuma Kazuyuki , Ashida Sakichi
Published: February 2003

Lead titanate PbTiO3 ceramics with a zero temperature coefficient of surface wave delay time are developed by addition of Nd2O3, In2O3, and MnO2. These ceramics have very small temperature coefficients of less than 1 ppm/ °C over a wide temperature range (−10–+60 °C). They have a large electromechanical coupling factor and low dielectric constant. The propagation loss is 4 dB/cm at 57 MHz. These modified PbTiO3 ceramics have high potential for use in surface wave applications, e.g., filters.
Laser-induced vapor deposition of silicon
Authors: Hanabusa M. , Namiki Akira , Yoshihara Keitaro
Published: February 2003

Silicon films were deposited when silane was irradiated with a pulsed CO2 laser. This laser-induced vapor deposition occurs effectively when the laser is tuned to an absorption frequency of SiH4. Efficiency was so high that an unfocused beam of 1.3 MW/cm2 sufficed. Any thermal effects are ruled out. Deposition is induced efficiently at gas pressures above 100 Torr, indicating that a collision-aided process is involved.
Pulse electron annealing of ion-implanted InP
Authors: Davies D. Eirug , Lorenzo J. P. , Ryan T. G. , Fitzgerald J. J.
Published: February 2003

Pulsed electron beam annealing has been used to activate high-dose silicon implants in InP. Peak concentrations ≳ 1019 cm−3 are obtained without any appreciable carrier freezeout on cooling to 78 °K. Such activation is comparable to that obtained on thermal annealing and is seen on samples implanted at both room temperature (amorphous) and 200 °C. In common with the behavior reported for GaAs, the mobility is similarly curtailed below thermally annealing values. Though the initial polished appearance is generally retained, unusual thermal oxidation and anodization properties suggest the possibility of surface phosphorous loss.
Optical bistability and signal amplification in a semiconductor crystal: applications of new low-power nonlinear effects in InSb
Authors: Miller D.A.B. , Smith S. D. , Johnston A.
Published: February 2003

We report the observation of optical stability for a plane parallel semiconductor crystal which forms a Fabry-Perot interferometer using only the natural reflectivity of its surfaces. Nonlinear transmission is observed for cw laser intensities above ∼ 100 W/cm2 for radiation at 1895 cm−1 near the energy gap of InSb at 5 K. The effect is interpreted in terms of a very large intensity-dependent refractive index giving a 5λ/2 optical thickness change for an intensity of ∼2 kW/cm2. Clear bistability is seen in fifth-order interference, the first such observation above first order in an intrinsic, one-element system, in addition to regions exhibiting signal amplification. The same crystal also shows strong modulation of the transmission of one laser beam induced by a second, with real signal gain, thus demonstrating an ’’optical transistor.’’
Efficient infrared ac Kerr switches using simple cryogenic liquids
Authors: Brueck S. R. J. , Kildal Helge
Published: February 2003

An efficient ac Kerr switch for the transfer of temporal pulse shapes between the visible and infrared spectral regions has been constructed using liquid O2. Employing group velocity matching techniques, this switch, which is applicable throughout the infrared, has ultimate switching speeds of 0.1–0.3 ps.