bluuebunny/crossref_metadata_2025 huggingface dataset:
High-power leaky-mode multiple-stripe laser
Authors: Ackley D. E. , Engelmann R. W. H.
Published: February 2003

A new multiple-stripe injection laser has been developed. By fabricating a stripe array of buried heterostructures configured to operate in leaky modes, strong coupling is produced between the stripes leading to linear operation and stable output characteristics. Efficient utilization of the total emitting area results from leaky-mode operation, and peak pulsed output powers to 1.5 W have been observed.
Optical self-pulsation behavior of cw (AlGa)As shallow proton-bombarded and narrow-striped (5 μm) double-heterostructure lasers grown by molecular beam epitaxy
Authors: Tsang W. T. , Holbrook W. R. , Fraley P. E.
Published: February 2003

A statistical study of the self-induced pulsation behavior of cw (AlGa)As double-heterostructure (DH) (having Al0.08Ga0.92 As active layers) proton-bombarded stripe lasers grown by molecular beam epitaxy (MBE) during accelerated aging at elevated (55 or 70 °C) temperatures is made and compared with that of similar lasers grown by liquid-phase epitaxy (LPE). For the 5-μm-stripe, shallow proton-bombarded (proton damage does not reach the active layer) stripe lasers, those fabricated from an MBE DH wafer studied show a significantly higher oscillation frequency (Fosc) of the self-pulsation than those fabricated from LPE DH wafers. It is also shown that by going from 10-μm-stripe and deep proton-bombarded (proton damage penetrates the active layer) to 5-μm-stripe and shallow proton-bombarded stripe lasers, the Fosc are significantly higher even after an initial burn-in at elevated temperatures (55 or 70 °C) for 100 h.
Surface acoustic wave frequency trimming of resonant and traveling-wave devices on quartz
Authors: Tanski William J.
Published: February 2003

A procedure for the postfabrication frequency adjustment (trimming) of narrow-band surface acoustic wave devices on quartz is described. This procedure utilizes selective etching of a quartz substrate by means of a tetrafluoromethane + oxygen (CF4+O2) plasma, to permanently change the physical configuration of the transducers by increasing the step height of metal electrode structures. An increase in energy storage at the step edges and an increase in transducer reflectivity (for resonators) contribute to a reduction in device frequency. This technique is simple, it may be readily implemented using several types of equipment, and the long-term aging rate of a devce is not changed. The technique may be used for resonators, which may be trimmed by etching the transducers only, and with delay-line type filters having any electrode configuration.
Electrical properties of laser chemically doped silicon
Authors: Deutsch T. F. , Ehrlich D. J. , Rathman D. D. , Silversmith D. J. , Osgood R. M.
Published: February 2003

The electrical properties of single-crystal and amorphous Si, doped using a pulsed UV laser, have been studied as a function of laser wavelength and fluence and of UV dose. BCl3 or PCl3 parent gases were used to provide B or P dopant atoms. Dissociation of molecules adsorbed on the Si surface can supplement photolysis of gas-phase molecules as a source of doping atoms.
Fine structure of voltage levels in the I-V characteristics of the rf SQUID’s
Authors: Ben-Jacob E. , Abraham D.
Published: February 2003

Results of digital numerical calculations of the rf-(SQUID) superconducting quantum interference device dynamics and I-V characteristics are presented. Fine structure of voltage levels in the I-V characteristics were found. We have introduced thermal noise effects via Langevin term in the equations of motion. The thermal noise causes transitions between the voltage levels. In the case of a SQUID with an underdamped junction, negative slope can be observed, which is due to to the transition to the lower voltage levels.
Liquid phase epitaxial growth of cadmium-doped InGaAsP/InP double heterostructure lasers
Authors: Tamari N.
Published: February 2003

Cadmium-doped InGaAsP/InP double heterostructure lasers (λ∼1.3 μm) have been made for the first time with threshold current densities as low as 1 kA/cm2. The low diffusion rate and distribution coefficient of cadmium facilitate locating the p-n junction reproducibly at the active region. High yield from a given wafer and a very uniform performance in a wide range of dopant concentrations are observed. The high vapor pressure of the Cd which has deterred previous investigations of this dopant does not seem to be a problem under the conditions used.
Interferometric determination of the sound speed in magnetized plasma using time-delayed correlation techniques
Authors: Jacobson A. R.
Published: February 2003

Time-delayed correlation measurements with a CO2 laser, multichord plasma interferometer show density perturbations propagating along the local magnetic field in the edge region of the ZT-40M reversed field pinch. The observed speed is consistent with ion-acoustic propagation. Such measurements of field-parallel waves with long wavelength (λ∥ ≳several centimeters) may provide a quasilocal, quasi-cw diagnostic of the sound speed in many low β magnetically confined plasmas, useful in estimating plasma temperatures.
New type of pulsed ion source with cryogenic anode
Authors: Kasuya K. , Horioka K. , Takahashi T. , Urai A. , Hijikawa M.
Published: February 2003

A magnetically insulated diode with a cryogenically refrigerated anode is proposed and a prototype of such a diode is constructed. H2O ice is produced on an anode which is cooled with liquid nitrogen. A small machine, consisting of a marx generator and a blumlein line, is used to extract ion beams from the diode. Proton beams of about 50 A and 70 keV are obtained with good reproducibility. Diode electrical characteristics and the extracted beam performance are also examined.
A gallium phosphide high-temperature bipolar junction transistor
Authors: Zipperian T. E. , Dawson L. R.
Published: February 2003

Transistor action at temperatures from 20 to 450 °C has been demonstrated for p+n−pp+ bipolar structures fabricated in GaP. Improvements in the materials technology were essential to successful fabrication of these devices. The structural configuration chosen could also be used as a junction field-effect transistor although this mode of operation was limited by the initial design to lower operating temperatures. While present device characteristics are restricted by ohmic contact resistance, this does not appear to be a fundamental limitation. These results demonstrate that GaP is a good materials candidate in which to base a technology for active electronic components operated at high temperatures.
Carrier mobility in polycrystalline semiconductors
Authors: Ram Kumar K. , Satyam M.
Published: February 2003

This letter presents a modified version of the grain boundary barrier model for polycrystalline semiconductors which takes into account the carrier transport in the bulk of the grain and the dynamic process of capture and release of free carriers by the grain boundary traps.
Au on Si (111): A study of the interface under UHV conditions and its modifications in air by surface techniques and MeV ion scattering
Authors: Derrien J. , Cohen C. , Cros A. , Layet J. M. , Salvan F. , Abel F. , Boulliard J. C. , Domange J. L. , Sotto M.
Published: February 2003

Auger and electron loss spectroscopies, low energy electron diffraction (LEED) and depth profiling techniques have been applied to the study of the Au/Si (111) interface under UHV conditions. The results, obtained at room temperature, show the formation on top of the substrate of (i) a diffuse and alloyed interface of ∼15-Å thickness, (ii) a pure Au film, and (iii) a Si enriched surface monolayer. The modifications of the interface structure in air have been checked by MeV ion microanalysis and channeling, for various gold coverages ranging between ≃1 monolayer up to ?100 Å. In all cases, drastic changes occur. Results related to 18O tracing experiments confirm the presence, under UHV, of Si atoms on the topmost layer. But the main fact is that a very strong Si diffusion through the gold layer takes place in air at room temperature for all the samples studied, leading to the formation of a surface silicon oxide layer much thicker than observed on samples without gold coverage.
Microslip-induced degradation in a braided superconductor
Authors: Tsukamoto O. , Maeda H. , Iwasa Y.
Published: February 2003

Based on results of two quite different experiments, we report microslip-induced degraded performance of a braided superconductor. Microslips, or more formally, microscopic slips, are inherent in all sliding events and are quite different from the well-known stick slips that occur, on a macroscopic scale, for ’’unstable’’ sliding pairs. Microslips occur universally in all material pairs. Their effects are, in general, innocuous except in low-temperature situations such as those found in superconducting magnet windings. Because materials have extremely low-heat capacities at 4.2 K, the miniscule amount of energy released by a microslip can precipitate a quench in the superconducting magnets.
Amplified phase conjugate reflection of KrF laser radiation
Authors: Caro R. G. , Gower M. C.
Published: February 2003

We report amplified phase conjugate reflection of KrF laser radiation at 249 nm using degenerate four-wave mixing in a solution of rhodamine 6G in ethanol. Reflectivities of ∼300% have been measured. Saturation of the reflectivity at high probe intensities was observed and the temporal dependence of the reflectivity has been investigated. The importance of mutual coherence of the probe and pump for the thermally induced nonlinearity involved in the process has been demonstrated.
Native tellurium dioxide layer on cadmium telluride: A high-resolution electron microscopy study
Authors: Ponce F. A. , Sinclair R. , Bube R. H.
Published: February 2003

An epitaxial tellurium dioxide layer has been observed on an oxidized {110} surface of a cadmium telluride single crystal. The structure of the oxide layer has been determined using high-resolution transmission electron microscopy (TEM) and identified as that of the mineral tellurite (TeO2). The interface is abrupt and coherent throughout the observed region. Crystallographic relationships at the interface suggest a model for oxidation.
Laser microreaction for deposition of doped silicon films
Authors: Ehrlich D. J. , Osgood R. M. , Deutsch T. F.
Published: February 2003

An Ar-ion laser has been used to activate surface pyrolytic deposition of polycrystalline Si in a several micrometer reaction zone. Controlled doping with boron during deposition allows one-step direct writing of highly conducting Si lines with linewidths as small as 1 μm. An unexpectedly fast deposition rate is associated with changes in the reaction kinetics as the dimensions of the reaction volume are reduced to microscopic lengths.
Room-temperature electron diffusion lengths in liquid phase epitaxial InGaAsP and InGaAs
Authors: Tashima M. M. , Cook L. W. , Stillman G. E.
Published: February 2003

Room-temperature electron diffusion lengths (Ln) were determined for lattice matched, p-type InGaAsP and InGaAs layers grown by liquid phase epitaxy on Sn-doped (100)-InP substrates by measuring the variation of the short-circuit photocurrent as a focused laser beam was scanned along a beveled (ϑ∼1 °) p-n junction. The hole concentrations, determined by capacitance-voltage (C-V) measurements, indicated an almost linear relationship between the hole concentrations in both the quaternary and ternary layers and the amount of Zn in the melt for the growth temperatures and substrate orientation used in this work. The electron diffusion lengths were longest at the lowest hole concentrations and decreased monotonically as the concentration increased. At the lowest doping levels, Ln was 3.5 μm at p = 3×1015 cm−3 for the quaternary and 2.5 μm at p = 1.4×1016 cm−3 for the ternary. At the highest hole concentration (p = 5×1018 cm−3) Ln was 0.13 and 0.83 μm for InGaAsP and InGaAs, respectively.
Electronic transport and microstructure in molybdenum silicide thin films
Authors: Weinmeister Roger E. , Mahan John E.
Published: February 2003

Electronic transport and microstructure were investigated in molybdenum silicide thin films prepared by ion beam sputtering from a MoSi2 powder source. Auger and x-ray analysis of the as-deposited films indicated a gross Mo/Si atomic ratio of ∼1/2, but a probable microstructure of strongly oriented Mo5Si3 crystallites in a Si-rich amorphous matrix. High-temperature annealing reduced the room-temperature resistivity by almost an order of magnitude, changed the sign of the temperature coefficient from negative to positive, and increased the Hall coefficient. The annealing also apparently increased the volume fraction of the film occupied by the oriented Mo5Si3 phase. It is shown that detailed transport data is needed for correctly evaluating the potential of refractory metal silicides as an improved gate electrode and interconnection material for integrated circuits.
Cyclotron resonance linewidth in selectively doped GaAs-AlxGa1−xAs heterojunctions
Authors: Voisin P. , Guldner Y. , Vieren J. P. , Voos M. , Delescluse P. , Linh Nguyen T.
Published: February 2003

Far-infrared cyclotron resonance (CR) experiments in a selectively doped AlxGa1−xAs -GaAs heterojunction are presented. Quantum oscillations appear in the CR line amplitude as theoretically predicted for a two-dimensional electron gas. The CR linewidth is found to depend on the infrared photon energy, and its correlation with the static mobility is interpreted in the framework of the Ando and Uemura’s model for a two-dimensional electron gas in a high magnetic field.
Infrared technique for study of thin-film interfaces
Authors: Gungor A. , Drew H. D. , Verdun H. R. , Jensen J. D.
Published: February 2003

Far-infrared studies have been made of n-type epitaxial PbTe films at high magnetic fields making use of the Nernst–Ettingshausen effect. The data are analyzed in terms of a parabolic band model of the conductivity tensor and a model for the heat flow in the sample. Comparison of measurements made with the radiation incident from the vacuum side with those with radiation incident from the substrate side of the sample gives information about the electronic structure at the two interfaces of the film.
Redissolution of precipitated oxygen in Czochralski-grown silicon wafers
Authors: Shimura Fumio
Published: February 2003

The redissolution behavior of precipitated oxygen in Czochralski-grown silicon wafers during high-temperature annealing (1230 °C) is investigated by means of infrared absorption and transmission electron microscopy. It is shown that the oxygen redissolution rate, which is 102∼103 larger than the precipitation rate, is highly dependent on the oxygen precipitation temperature which in turn determines the form of the precipitates. The dependence is described by the difference in the total surface area of precipitates and by the dislocation pinning effect.
p-n junction formation in n-AlGaAs by beryllium ion implantation
Authors: Comas J. , Bedair S. M.
Published: February 2003

Beryllium-implanted liquid phase epitaxy n-AlGaAs layers have exhibited p-n junction behavior after annealing. Graded or abrupt junction behavior was found to be implant fluence dependent. Secondary ion mass spectrometry Be concentration profiles indicate that the graded junctions observed for the higher fluence implants were due to in-depth migration of Be. Mesa diodes have shown ideality factors of about 2 and avalanche breakdown in reverse bias.
Tunable oscillator using pulsons on large-area lossy Josephson junctions
Authors: Christiansen Peter L. , Lomdahl Peter S. , Zabusky Norman J.
Published: February 2003

A tunable resonator in the gigahertz-range using circular sine-Gordon fluxons or pulsons on a lossy large-area Josephson junction with a circular impurity in the Josephson current density is proposed. To obtain steady tunable oscillations in a lossy medium, one must supply energy (’’negative’’ resistance). We propose to control the constant bias current with an autonomous pulson velocity-sensitive switch. One possibility for fine tuning the oscillations is to vary the strength of the Josephson impurity current.
Reaction of Nb alloys with Al2O3 to form high T
c Nb3Al
Authors: Schmidt P. H. , Rowell J. M. , Feldmann W. L.
Published: February 2003

We report that the reaction of Nb with sapphire substrates at moderately high temperatures (≲1100 °C) is enhanced by mixing with Nb, a metal which has a higher oxygen affinity than Al. For example, the reaction of NbZr with Al2O3 at 950 °C results in the formation of zirconium oxide and Nb3Al with a superconducting Tc ≳17 K.
A direct nuclear-pumped 3He-CO laser
Authors: Jalufka N. W. , Hohl F.
Published: February 2003

Direct nuclear pumping of a low-temperature (≊150 K) 3He-CO laser has been achieved using the volumetric 3He(n,p) 3H nuclear reaction. Lasing occurred on the vibrational bands of CO at ≊5 μ. Effects of N2 on the system were investigated, as well as scaling of laser output with CO concentration, thermal neutron flux, and total pressure. This is the first volume-pumped, nuclear powered CO laser.
Effect of rare-gas diluents on the performance of an XeCl laser pumped by a high-intensity electron beam
Authors: Tisone Gary C. , Hoffman James M.
Published: February 2003

The effect of various rare-gas diluents on the operating parameters of the XeCl laser has been investigated. The laser was electron-beam pumped at an excitation rate of ≊3 MW/cm3 and a pulse duration of 50 nsec. Contrary to previous results we found that the intrinsic efficiency, small-signal gain, and absorption were independent of the rare-gas diluent. The intrinsic efficiency was ≊ 4%, the small-signal gain was 0.18 cm−1, and the absorption coefficient was between 0.04 and 0.05 cm−1. A saturation intensity of 3 MW/cm2 was obtained from a modified Rigrod analysis of the data.
The effect of laser annealing on the critical-current density in Nb3Ge
Authors: Braginski A. I. , Gavaler J. R. , Kuznicki R. C. , Appleton B. R. , White C. W.
Published: February 2003

Pulse laser annealing of Nb-Ge superconducting films grown by chemical vapor deposition produces an increase in critical-current density, Jc, if the atomic ratio Nb/Ge is less than three. This Jc increase is caused by flux pinning on the nucleated Nb5Ge3(σ) second-phase particles rather than on grain boundaries in the melted and resolidified surface layer. This resolidified layer is amorphous or highly disordered.
A magnetically stabilized radial discharge for a high-powered laser
Authors: Seguin H. J. J. , Capjack C. E. , Antoniuk D. , Seguin V. A.
Published: February 2003

Details of a new ’’magnetically stabilized’’ coaxial electrode system supporting a radial discharge geometry is presented. Performance was found to be largely independent of gas mixture and pressure such that high-power cw discharges were easily obtained in all the gases tested, including SF6. The technique is exceedingly simple and appears scalable to provide a very large active volume in an unusually small physical package. A cw power loading in excess of 40 kW/l has already been attained without experiencing any glow-to-arc transitions.
Acoustic detection of electron spin resonance
Authors: Coufal H.
Published: February 2003

The electron spin resonance (ESR) signal of diphenylpicrylhydrazyl was recorded by detecting the modulation of the absorbed microwave power with a gas-coupled microphone. This photoacoustic detection scheme is compared with conventional ESR detection. Applications of the acoustical detection method to other modulation spectroscopic techniques, particularly nuclear magnetic resonance, are discussed.
Study of a gas-solid dielectric interface by means of surface depolarization thermocurrents
Authors: Despax B. , Ai Bui , Abdullah M. , Huraux C.
Published: February 2003

The method of thermally stimulated currents (TSC), with a special configuration of electrodes, was used to study interfacial reactions on a soda glass surface exposed to a highly polarizable gas such as carbon dioxide. Two well-developed peaks were observed at −100 and −120 °C, which were completely absent from the volume response of the same material. The peaks disappeared on prolonged heat treatment of the specimen in vacuum. The results were interpreted in terms of polarization phenomena introduced near the surface of the glass by the presence of highly polarizable molecules.
X-radiographic studies of ablatively driven relativistic electron beam targets
Authors: Chang J. , Fehl D. L. , Widner M. M. , Bieg K. W. , Palmer M. A.
Published: February 2003

Studies of ablatively driven, relativistic electron beam target implosions have been made with a two-frame, 3-ns exposure flash, x-radiography system. The spherical targets were filled with 200 atm of deuterium gas and had a copper shell thickness greater than the electron range. In addition, the copper shell was lined with a thin gold layer which permitted direct radiographic observations of the Au liner, achieving thereby direct observation of the pusher fuel boundary. The gold liner was observed to implode at a radial velocity of 2×105 cm/s, while maintaining better than a±7% variation in radial position. From the measured convergence ratio we have inferred a maximum fuel density, in the compressed state, of greater than several times solid density.
Effect of substrate surface treatment in molecular beam epitaxy on the vertical electronic transport through the film-substrate interface
Authors: Chang Chin-An , Heiblum M. , Ludeke R. , Nathan M. I.
Published: February 2003

We have grown n+ -GaAs films using Sn or Ge doping on n+ -GaAs substrates by molecular beam epitaxy and studied the vertical electronic transport through the film-substrate interface. An interfacial layer with high resistance and a nonlinear I-V characteristic is observed whenever the substrates have been sputter-cleaned and annealed prior to the growth. Similar results are observed for the nonsputtered substrates with a high surface coverage of carbon. Such an interfacial layer can be eliminated in both cases by a predeposition of a Sn monolayer prior to the growth of the n+ -GaAs layers.
Epitaxial Ge/GaAs heterostructures by scanned cw laser annealing of a-Ge layers on GaAs
Authors: Greene J. E. , Cadien K. C. , Lubben D. , Hawkins G. A. , Erikson G. R. , Clarke J. R.
Published: February 2003

Expitaxial Ge/GaAs heterostructures have been produced by scanned cw argon laser annealing of 440-nm-thick amorphous Ge films on (100) semi-insulating GaAs substrates. Depending on the incident laser power and scan rate, two modes of film regrowth were observed. At low powers (between ∼1.6 and 4.0 W for a beam diameter of ∼40μm) and scan rates between 1 and 400 cm/sec, polycrystalline Ge with a (100) preferred orientation was formed by an ’’explosive’’ crystallization mechanism. At higher powers, and over a scan rate range of 20–400 cm/sec, single-crystal films containing some dissolved GaAs in solution were obtained by liquid phase regrowth. Typical film resistivities ρ were as follows: as-deposited, ρ = 180 Ω cm; polycrystalline films, ρ = 3×10−2 cm; single-crystal films, ρ = 9×10−4Ω cm.
High concentration antimony diffusion into silicon using auxiliary wafers
Authors: Nanba M. , Kozuka H. , Usami K.
Published: February 2003

The behavior of auxiliary wafers used for Sb diffusion has been studied, with the auxiliary wafers set face to face with diffusion wafers. A high Sb concentration, as high as the solid solubility of Sb into silicon, was attained by auxiliary wafers lapped with alumina powder but not attained by those lapped with carborundum powder. Sapphire substrates, chemical vapor deposition-Al2O3 film deposited on silicon wafers, and Al+ -implanted silicon wafers were used for the auxiliary wafers, and they brought desirable results. Chemical analysis showed that the glass layer grown on the diffusion wafer contained aluminum oxide, which was estimated to give a high Sb concentration in the diffusion wafer.
Direct nuclear excitation of a 3He-CO2 gas mixture
Authors: Jalufka N. W.
Published: February 2003

Probe measurements using a continuous wave CO2 laser have been carried out on a 3He-CO2 gas mixture directly excited by the 3He(n,p)3H reaction. At a gas pressure of 1 atm and thermal neutron flux up to 1×1017 n/cm2 sec, total extinction of the probe beam was observed. Addition of N2 to the gas mixture (up to 20%) produced a media such as is used in electric discharge CO2 lasers. However, this mixture produced the same results as the 3He-CO2 mixture. Absorption of the laser beam indicates that with direct nuclear excitation, it is the lower laser level which is excited. Therefore direct nuclear pumping of a CO2 laser does not appear feasible.
A visible (AlGa)As heterostructure laser grown by molecular beam epitaxy
Authors: Tsang W. T. , Ditzenberger J. A.
Published: February 2003

Visible (AlGa)As double-heterostructure lasers with a 200-Å Al0.17Ga0.83As active layer have been prepared by molecular beam epitaxy. The diodes lase at ∼7520 Å and have an average pulsed threshold current density Jth of 810A/cm2, which agrees for the first time with the value calculated from first principles without adjustable parameters by Casey, Jr., in the very thin active-layer regime. The far-field half-power full-width ϑd in the direction perpendicular to the junction plane is as narrow as 11 °. The temperature coefficient T0 of the temperature dependence of threshold is 110 K.
Anisotropic suspension display
Authors: Beni G. , Craighead H. G. , Hackwood S.
Published: February 2003

We show that an anisotropic suspension can be rapidly (∼1 msec) switched between two states of different refractive index by applying a low voltage (∼1 V). We propose a display design that utilizes this refractive index change to produce transmittance modulations from ≳95% to <10% in single pass.
Wavelength-multiplexed A
N
D gate: A building block for monolithic optically coupled circuits
Authors: Copeland J. A. , Campbell J. C. , Dentai A. G. , Miller S. E.
Published: February 2003

A device which performs the binary logic and function has been demonstrated, which uses optical signals with different wavelengths as inputs and provides an electrical output capable of triggering a trap-doped laser. Wavelength multiplexing of inputs makes possible a compact structure, which may be a basic building-block device in monolithic optically coupled circuits.
Generation-recombination centers in p-type Hg1−xCdxTe
Authors: Jones Colin E. , Nair Vijayan , Polla Dennis L.
Published: February 2003

Hg1−xCdxTe photodiodes have long been thought to be limited by recombination-generation centers. The minority carrier lifetime τe in many samples of p-type Hg1−xCdxTe has been explained assuming a midgap Shockley–Read center. This modeling is not unique and does not fully characterize the center. This letter reports deep level transient spectroscopy (DLTS) data on a series of x = 0.2–0.4 p-type Hg1−xCdxTe samples. The DLTS data confirms the Shockley–Read model in that there is a commonly observed recombination center just below midgap. Another center near 3/4 Eg is also observed. Both of these centers can be important in controlling lifetime and detector performance.
Pyrometric measurement of temperature during cw argon-ion laser annealing and the solid-state regrowth rate of amorphous Si
Authors: Sedgwick T. O.
Published: February 2003

A standard pyrometer is modified with a long working distance magnifier and used to measure temperature in situ during cw argon laser annealing of ion-implanted Si. The measured temperatures of 1020 and 1077 °C and observed regrowth rates for 900 Å of amorphous Si in 2×10−4 and 4×10−4 sec respectively agree reasonably well with the solid-state Si regrowth rate previously determined by others from furnace annealing experiments in the minutes to hours time regime.
Measurement of HCl electron attachment in relation to XeCl laser kinetics
Authors: Kligler D. , Rozenberg Z. , Rokni M.
Published: February 2003

The electron attachment rate constant of HCl is measured in e-beam-excited mixtures of N2/HCl and Ar/H2/HCl, by observing the electron current decay after termination of an e-beam pulse. The possible enhancement of attachment due to vibrational excitation of HCl under e-beam pumping is studied, by performing measurements with e-beam currents differing by a factor of 30. The consequences of the results for XeCl laser kinetics are discussed.
Improved oxide of metal-oxide-silicon capacitors resulting from backsurface argon implantation
Authors: Yun B. H.
Published: February 2003

Argon ions were implanted at the backsurface of silicon wafers prior to the formation of the oxide of the metal-oxide-silicon capacitors. The implantation resulted in improved oxide. The improvement is speculated to be a consequence of the gettering of the metallic impurities by the dislocations caused by the ion implantation gettering which occurs during oxidation and prevents the impurities from being absorbed into the oxide of the subsequent capacitors.
Thin-film waveguiding evanescent dye laser with a corner reflecting resonator
Authors: Sasaki K. , Saito T. , Serizawa M. , Furukawa S. , Hamano O.
Published: February 2003

A thin-film optical waveguiding evanescent dye laser was realized by an activated square-shape Rh6 G top layer on a thin-film glass waveguide. When a N2 UV laser was focused on a diagonal line of the square dye film by a cylindrical lens, a pair of corners played a role as a corner reflecting resonator. A distinct resonance and transverse modes were observed.
Multi-Joule pulses from a sequence band transversely excited atmospheric CO2 laser
Authors: Brimacombe R. K. , Reid J. , Znotins T. A.
Published: February 2003

We have used an in-cavity hot CO2 cell to convert a conventional transversely excited atmospheric (TEA) CO2 laser to operation on the 00 °2 sequence transitions. Careful cavity design enables us to attain efficient energy extraction. Output energies of 6 J per pulse have been obtained from a nonselective cavity, while a grating-tuned cavity produces numerous sequence lines having output energies in excess of 2 J per pulse.
Mechanically scanned B-scan system for acoustic microscopy of solids
Authors: Wickramasinghe H. K.
Published: February 2003

We propose a novel mechanically scanned B-scan system for imaging the interior of solids with diffraction-limited resolution. By utilizing an additional spherical surface in conjunction with a conventional acoustic lens, it is possible to reduce spherical aberration, (which would otherwise seriously degrade the imaging performance), to a negligible value. In typical situations, it is possible to scan the focus through a depth of several hundred wavelengths.
Influences of gas flow on chemical vapor deposition of superconducting Nb-Ge films
Authors: Suzuki Mitsumasa , Onodera Hiroshi , Anayama Takeshi , Oya Gin-ichiro , Onodera Yutaka
Published: February 2003

Nb-Ge films, which have been prepared by chemical vapor deposition, have been studied for superconducting transition temperatures, crystal structures, and growth morphology. In the films a relationship was obtained among positions at which the highest Tc films are deposited, the degree of orientation for A15 crystallites is lowered, and the microstructures for film surface change has been found. This can be explained in terms of a higher deposition rate of Ge than that of Nb.
Observation of large room-temperature coercivity in melt-spun Nd0.4Fe0.6
Authors: Croat John J.
Published: February 2003

An intrinsic room-temperature coercivity of 7.45 kOe has been found in melt-spun Nd0.4Fe0.6; this value is the largest ever reported for a rare-earth–iron alloy. A significant correlation was found between quench rate and coercivitiy, suggesting that the quenched alloys consist of fine crystallites or clusters, whose average particle size can be matched to the single-domain optimum by the appropriate quench rate.
A Josephson vortex-flow device
Authors: Rajeevakumar T. V.
Published: February 2003

An inverting, nonlatching switching device capable of analog as well as digital signal amplification is investigated experimentally and theoretically (numerical simulations). The device reported is based on the dynamic properties of long Josephson junctions. It is shown that current gain of the order of 5 can be achieved in a 2.5-μm technology, for small resistive loads of the order of 0.5 Ω.
Theory of subharmonically pumped mixing with gain using superconductor-insulator-superconductor junctions
Authors: Slusky S. E. G. , Trambarulo R.
Published: February 2003

We show in principle that a hysteretic superconductor-insulator-superconductor junction can function as a subharmonically pumped mixer with gain. The mixer can be operated either as a nearly linear downconverter or as a highly nonlinear threshold detector. The gain in the linear mode is an inverse function of the pump power. We present the results of computer analysis of both mixing modes.
Formation of WxSi1−x by plasma chemical vapor deposition
Authors: Akimoto K. , Watanabe K.
Published: February 2003

Smooth films of W-Si compounds (WxSi1−x) were successfully formed by plasma chemical vapor deposition using WF6 and SiH4. The atomic ratio of W/Si in the film depended on the flow rate of WF6/SiH4. The WxSi1−x obtained when x was less than 0.45 was amorphous even after the film was annealed at 1100 °C for 60 min in N2 ambient. The crystalline phase of W was observed when x is 0.99 in an as-deposited film. Distribution of W atoms in the film was found to be uniform. Resistivities of as-deposited films varied from ∼3×10−2 to ∼4×10−5 Ω cm, corresponding to x of from 0.04 to 0.99. For smaller x, the decrease in resistivity on annealing was marked.
Bistability and pulsations in cw semiconductor lasers with a controlled amount of saturable absorption
Authors: Harder Ch. , Lau K. Y. , Yariv A.
Published: February 2003

Experimental results of a buried heterostructure cw laser with a controllable amount of saturable absorption introduced by a segmented contact are presented. With no absorption the laser is stable and has a linear output characteristic. Increasing of the saturable absorption by changing the pump current through the control segment causes the light output of the device to pulsate and to show bistable and hysteretical behavior. The introduction of a controllable amount of saturable absorption suggest the usefulness of this device in generating extremely short pulses, for example, by passive mode locking and as a bistable optical device.
Plasma-enhanced metalorganic chemical vapor deposition of c-axis oriented and epitaxial films of ZnO at low substrate temperatures
Authors: Shiosaki Tadashi , Yamamoto Takashi , Yagi Mitsuo , Kawabata Akira
Published: February 2003

Thin-film zinc oxide with a high degree of c-axis orientation normal to the substrate surface has been grown on a glass substrate by plasma-enhanced metalorganic chemical vapor deposition of diethylzinc at a substrate temperature of 200 °C and rf input powers higher than 220 W in carbon dioxide and oxygen atmospheres. An epitaxial (112̄0) ZnO film has been also grown on a (011̄2) sapphire substrate at an rf input power of 80 W and a substrate temperature of 200 °C.
Oxygen-related donor states in silicon
Authors: Kimerling L. C. , Benton J. L.
Published: February 2003

Junction spectroscopy techniques have been applied to the study of defect states introduced by heat treatment of silicon containing ∼1018[O]/cm3. Two shallow electron traps are observed, whose concentrations increase with the electron concentration added during a 450 °C anneal. The zero field defect-state activation energies are E(0.07 eV) and E(0.15 eV). Both states display a Poole-Frenkel field emission process as expected for donors.
Polysilicon recrystallization by CO2 laser heating of SiO2
Authors: Weinberg Z. A.
Published: February 2003

CO2 laser emission matches the absorption of optical phonons in SiO2. This fact was used to couple the laser energy into a layer of SiO2 (510 nm) deposited over polysilicon (225 nm), which was deposited on thermally grown SiO2 (860 nm). In this manner, recrystallization of the polysilicon was achieved with a mosaic pattern of grains having sizes in the 1–30-μm range.
Annular grain structures in pulsed laser recrystallized Si on amorphous insulators
Authors: Celler G. K. , Leamy H. J. , Trimble L. E. , Sheng T. T.
Published: February 2003

Polycrystalline silicon films on SiO2 and Si3N4 may be processed by tightly focused, overlapping laser pulses to yield large-grained (1–5μm) material. In individual nonoverlapping spots the large grains are arranged in concentric rings whose origin is clarified in this letter.
Emission properties in electrolytically prepared CdTe p-n junctions
Authors: Saldaña Xochitl I. , Vázquez-López C. , Zehe A. , Navarro H. , Triboulet Robert
Published: February 2003

In this work p-n CdTe junctions have been prepared by the outdiffusion of Cd assisted by light using nCdTe electrodes in an electrolytic cell configuration. After removing the semiconductor from the electrolyte, electroluminescence experiments were performed in order to study the radiative processes that take place in these photoelectrolytically prepared devices. The observed electroluminescent lines could be explained by supposing two radiative transitions: from Cl impurity level (which is the dopant of the nCdTe) into a VCd-Sn complex, and from the conduction band into a level corresponding to the Cd vacancy. Their TO phonon replicas were also observed.
Picosecond photoconductivity in germanium films
Authors: DeFonzo A. P.
Published: February 2003

A picosecond photoconductive detector based on a new photoconductive material, ρ-Ge, is described. Photoconductivity measurements show relaxation times less than 50 ps and sensitivities greater than 0.1 mA/mW with 25-μm electrode spacings. A comparison is made with similar devices through the introduction of a merit-figure Fi, which we propose as being particularly suited to evaluating picosecond photodetectors. The device is capable of operation to wavelengths of 1.7 μm.
A comparison between selenium mass-transported and selenium-diffused silicon
Authors: Skarstam B. , Lennart Lindström J.
Published: February 2003

The appearance of the same excited-state ladder for the shallow center in selenium-doped and selenium mass-transported silicon is confirmed for the first time. The lifting of the effective-mass degenerate state in the two systems is seen in infrared absorption spectra as a peak at 2196 cm−1. The strength of this line is of the same order as that for the 2p0 line. The 3p± and higher excited states, in the mass-transported sample are obscured by line broadening mechanisms. This is believed to be due to the incorporation mechanism of the selenium atoms during crystal growth and their concentration. In both systems an additional line is resolved at Ec −9.3 meV, which is close to the theoretical value for the 2s excited states for group V donors. As for the strength of the 1s(A1)–1s(T2) line (at 2196 cm−1), the strength of this line is believed to reflect the chemical nature of the selenium-related optical defect center investigated.
The use of beam shaping to achieve large-grain cw laser-recrystallized polysilicon on amorphous substrates
Authors: Stultz T. J. , Gibbons J. F.
Published: February 2003

Laser beam shaping has been used to increase the grain size of laser-recrystallized polycrystalline silicon on amorphous substrates. Using a slanted liquid-solid interface, rectangular grains as large as 45×50 μm have been grown in 0.5-μm-thick chemical vapor deposited polysilicon on quartz substrates. Improved surface smoothness of recrystallized material has also been achieved using this procedure.
Subpicosecond pulse generation in a traveling-wave ring laser using a synchronous double-modulation scheme
Authors: Halbout J.-M. , Olsson A. , Tang C. L.
Published: February 2003

A new scheme for achieving traveling-wave operation in synchronously mode-locked ring lasers is demonstrated. The use of a very low dispersion electro-optic modulator yielded subpicosecond optical pulses with autocorrelation full-width at half-maximum (FWHM) as short as 0.7 ps and with wide tunability.
2nd–5th electron cyclotron harmonic emission from thermal plasmas in Alcator A
Authors: Woskoboinikow P. , Praddaude H. C. , Falconer I. S. , Mulligan W. J.
Published: February 2003

A sensitive submillimeter heterodyne receiver has been used to measure electron cyclotron emission at the 2nd through the 5th harmonics from thermal plasmas in Alcator A. A sensitive diagnostic of the electron energy distribution function is obtained from intensity ratios of the optically thin harmonics, in particular the small runaway fraction (∼10−6) that exists even in well thermalized Alcator A plasmas. Also the 4th and 5th harmonics are a sensitive measure of impending plasma disruption due to vessel air leaks.
Optical gain obtained by rapidly mixing cold CO2 and hot N2 gases within a gas throat
Authors: Kitagawa K.
Published: February 2003

A population inversion of the (001)–(100) transition in CO2 gas has been observed when the cold CO2 or CO2, and He gases were vertically injected into a high-temperature, thermally equilibrated, low-subsonic N2 flow in a duct having a constant area. Simultaneously, the formation of a gas throat was observed. A small signal gain of 0.95/m was measured at 2 mm downstream from a gas injecting point.
Nuclear-pumped lasing of 3He-Xe at 2.63 μm
Authors: Jalufka N. W.
Published: February 2003

Direct nuclear pumping of a 3He-Xe laser, lasing at 2.63 μm, has been achieved. Scaling of the laser output with xenon concentration, total pressure, and thermal neutron flux has been investigated. A peak power in excess of 200 W was obtained at a total pressure of 3 atm, a gas mixture consisting of 5 % xenon and 95% 3He, and a peak thermal flux of 6×1016 n/cm2 s.
A novel current injection Josephson logic gate with high gain
Authors: Hohkawa Kohji , Okada Masaru , Ishida Akira
Published: February 2003

A novel Josephson logic gate achieving high gain, employing current injection, and having a noninterferometer configuration has been proposed and studied. The gate includes three small junctions for input sensing, output driving, and I-O isolation. The junctions are appropriately biased by source resistors to obtain high current gain. Computer simulation and preliminary experiment have demonstrated that a current gain higher than 2 can easily be obtained through the proposed configuration.
Characterization of wet (D2O) thermal oxidation of silicon by secondary ion mass spectrometry
Authors: Mikkelsen J. C.
Published: February 2003

Secondary ion mass spectrometry was used to profile deuterium concentrations [D] in 100-200-nm-thick SiO2 films, which were grown by thermal oxidation of silicon in D2O steam pressures of 0.05-8 atm and at temperatures of 550-1000 °C. Deuterium was used to simulate hydrogen chemistry in steam oxidations and is readily detected in the presence of high background concentrations of hydrogen in the sputtering ambient. Structure observed here in D profiles, and previously in H profiles, near the SiO2-Si interface are due predominantly to abrupt changes in ion yields as the surface charging conditions change. The 1-atm profiles generally exhibit an increase in [D] in the SiO2 toward the Si interface; the average [D] is nearly constant at 0.6-1.0×1020 cm−3 for oxidations at 800-1000 °C and rises to 6×1020 cm−3 at 600 °C. It is argued that the D is predominantly in the form of Si-OD. At 800 °C and 0.05-8 atm, the average OD concentration in the oxide film is approximately proportional to (steam pressure)1/2. This is the first demonstration of the simple equilibrium reaction between ambient water and the as-grown oxide layer.
Molecular-beam epitaxial growth of uniform Ga0.47In0.53As with a rotating sample holder
Authors: Cheng K. Y. , Cho A. Y. , Wagner W. R.
Published: February 2003

Ga0.47In0.53As and Al0.48In0.52As were grown lattice matched to InP substrates with a rotating substrate holder. The Ga, In, and Al beams were supplied by separate effusion cells and the uniformity of the resulting layers was evaluated with x-ray rocking curves for different rotation speeds. Lateral variation of the lattice constant as small as 10−5 per cm may be achieved with a rotation speed of 3 rpm. The full width at half-maximum of the x-ray spectrum from the epitaxial layer is comparable to that of the substrate indicating that there is practically no compositional grading.
Modification of grain boundaries in polycrystalline silicon with fluorine and oxygen
Authors: Ginley David S.
Published: February 2003

Hydrogen plasmas have been shown to significantly reduce barrier heights and recombination center densities in the grain boundaries in polycrystalline silicon. These results have stimulated interest in the use of other modifying agents. We demonstrate here that the exposure of n-type polycrystalline silicon to fluorine and oxygen in molecular and atomic forms can result in increased potential barrier heights. This has implications for the development of silicon varistors and capacitors for use in integrated circuits.
Location of impurities in compounds by asymmetry of channeling dips
Authors: Andersen J. U. , Chechenin N. G. , Hua Zhang Zu
Published: February 2003

The location of substitutional impurities in GaP (Sb and In) has been investigated by channeling. The sites may be determined from the width of 〈110〉 backscattering dips, but a new technique based on asymmetry of the channeling dips is developed, which appears to be more powerful for compounds with ZnS structure. It requires smaller ion doses and may be applied also to compounds such as GaAs with nearly equal atomic number of the compound constituents. The technique may also be applied to determine the stacking order in a 〈111〉 direction of such compounds.
Laser heating of thermoluminescent dielectric layers
Authors: Bräunlich P. , Gasiot J. , Fillard J. P. , Castagné M.
Published: February 2003

Heating with pulsed or continuous CO2-laser beams is shown to be an attractive means for rapid evaluation of discrete or continuous two-dimensional arrays of small or thin thermoluminescent samples. Applications of the novel laser heating techniques to thermoluminescence imaging of spatial dose distributions of ionizing radiation and to the measurement of two-dimensional temperature distributions in high-laser power dielectric coating are discussed.
Variable axis lens for electron beams
Authors: Pfeiffer H. C. , Langner G. O. , Sturans M.
Published: February 2003

An electron optical focusing and deflection system for electron beam lithography has been developed which eliminates off-axis aberrations up to the third order including transverse chromatic errors by means of a variable axis lens (VAL). Feasibility of the VAL concept has been established experimentally.
Electrical properties of single-crystal silicon layers formed from polycrystalline silicon by solid phase epitaxy
Authors: Wang K. L. , Li G. P. , Sigmon T. W.
Published: February 2003

The electrical evaluation of metal-oxide-semiconductor (MOS) capacitors fabricated on thin films formed by low-temperature epitaxial crystallization of amorphized polysilicon layers on single-crystal Si substrates is presented. Shallow dopant and deep-level defect distributions are obtained using fast C(V) and deep-level transient spectroscopy, respectively. The dominant deep-level defects are observed to be at Ec −0.074 eV, Ec −0.15 eV, and Ec −0.46 eV. Both the shallow dopant and deep-level defect distributions exhibit peak concentrations near the original poly/single-crystal interface. These defects and impurities are attributed to gettering by oxygen of contaminant impurities. It is concluded from the data that these films are of suitable quality for MOS device fabrication, and techniques are suggested to further decrease the observed defect concentrations.