bluuebunny/crossref_metadata_2025 huggingface dataset:
Superconductor-insulator-superconductor quasiparticle junctions as microwave photon detectors
Authors: Richards P. L. , Shen T. M. , Harris R. E. , Lloyd F. L.
Published: February 2003

The strong nonlinearity of the quasiparticle tunneling current in superconductor-insulator-superconductor junctions near the full-gap voltage 2Δ/e can be used for direct detection of microwave signals. Measurements at 36 GHz yielded a current responsivity of 3500 A/W, which is within a factor of 2 of the quantum-limited value e/∇ω. The measured NEP of 2.6±0.8×10−16 W/,Hz1/2 is the lowest value reported to date and can probably be improved significantly. The experimental results are compared with both the standard classical analysis and photon-assisted tunneling theory.
A magnetostatic wave signal-to-noise enhancer
Authors: Adam J. D. , Stitzer S. N.
Published: February 2003

A new type of frequency selective signal-to-noise enhancer is described, which shows instantaneous bandwidths of more than 800 MHz at frequencies up to 4.2 GHz. The device consists of an epitaxial YIG film in contact with a narrow microstrip transmission line. Magnetostatic surface waves in the YIG film act as saturable absorbers of power from the microstrip line. Using a 26.6-μm-thick YIG film on a 23-μm-wide microstrip line of 21 mm length, resulted in a small signal (<−6 dBm) attenuation of in excess of 25 dB. The attenuation was reduced by 15 dB when the input power was increased to +10 dBm.
High-resolution saturated absorption spectroscopy with coherent trains of short light pulses
Authors: Couillaud B. , Ducasse A. , Sarger L. , Boscher D.
Published: February 2003

The feasibility of saturated absorption with two counterpropagating trains of short light pulses from a frequency-locked, synchronously pumped, mode-locked, cw dye laser is demonstated. In contrast with the experiments using a single-frequency laser, several velocity classes contribute to the signal, thus increasing the signal-to-noise ratio. In addition, the advantages reported for two-photon spectroscopy (precise frequency scale, increase of the second harmonic, etc.) are available in this new technique.
Growth rates for Pt2Si and PtSi formation under UHV and controlled impurity atmospheres
Authors: Crider C. A. , Poate J. M.
Published: February 2003

Platinum silicides have been prepared by depositing Pt thin films under ultrahigh vacuum (UHV) and controlled impurity atmospheres including a range of O2 partial pressures. The substrates and silicide films were analyzed with Rutherford backscattering spectroscopy (RBS) and Auger electron spectroscopy (AES). Growth of the silicide films was observed under UHV in real time with RBS. Growth rates (i.e. diffusivities) for Pt2Si and PtSi formation were observed to be one to three orders of magnitude higher than previously reported. Increasing partial pressures of O2 during Pt depositions caused the growth rates to decrease by up to a factor of 20 and caused disruption of the normal phase growth sequence; partial pressures of N2 and Ar had no effect.
Deep levels in scanned electron-beam annealed silicon
Authors: Johnson N. M. , Regolini J. L. , Bartelink D. J. , Gibbons J. F. , Ratnakumar K. N.
Published: February 2003

Electronic defect levels in scanned electron-beam annealed (SEBA) silicon have been measured by deep-level transient spectroscopy. In As+-implanted p-n junctions, hole-trap densities in the 1013-cm−3 range have been achieved with the dominant levels energetically situated for inefficient charge generation and recombination. In Schottky diodes on unimplanted silicon, SEBA-induced electron traps have been detected with principal levels at Ec−0.19 eV and Ec−0.44 eV; the defect densities decrease exponentially with distance from the beam-annealed surface. Both levels are ascribed to vacancy-impurity complexes (e.g., the 0.44-eV level identifies the P-V center), and a simple vacancy-diffusion model is proposed to explain the defect distributions.
Acoustoelectric measurement of electron mobility and diffusion in ultrathin evaporated gold films
Authors: Sader E. , Harnik E. , Kovnovich S.
Published: February 2003

The electron mobility, diffusion constant, and their dependence on sheet conductivity were derived from simultaneous measurements of acoustoelectric current, attenuation, and phase velocity change induced by the interaction of acoustic surface waves with electrons in thin gold films. The mobility results are consistent with the discontinuous island structure of such films in the interaction region. The effective diffusion constant obtained bears no relation to the corresponding mobility data, and its physical meaning is not clear. It is suggested that the observed ’’diffusion effects’’ are not real, but are simulated by the varying influence of growth characteristics on attenuation and phase velocity in discontinuous metal films.
Remote sensing of CO using frequency-doubled CO2 laser radiation
Authors: Killinger D. K. , Menyuk N. , DeFeo W. E.
Published: February 2003

Single-ended remote sensing measurements of the atmospheric concentration of CO using differential absorption of line-tunable, frequency-doubled CO2 laser radiation near 4.6 μm are reported. The concentration of CO was deduced from laser backscatter returns from topographic targets at ranges up to 2.5 km with an overall uncertainty of approximately 10 ppb. The use of several targets at different ranges but along the same line of sight permitted pseudo-range-resolved measurements and clearly established the strong localization of CO concentration over traffic roadways.
Determination of recombination lifetime in MOSFET’s
Authors: Soutschek E. , Müller W. , Dorda G.
Published: February 2003

A technique is presented for measuring the surface and volume minority-carrier recombination lifetime in MOSFET’s. The method, based on the charge pumping effect, is particularly useful for measurements on MOS transistors which have passed the whole technological process. Room temperature and nitrogen temperature results are presented. A further advantage of this technique is the simplicity in equipment and analysis of the data.
Observation by Auger electron spectroscopy of the effect of hydrogen at a (111) Si-SiO2 interface
Authors: Jost Steven R. , Johnson Walter C.
Published: February 2003

Recent studies have shown that the Si-SiO2 interface is the source of an Auger peak at approximately 81–83 eV. Here we present the observation that exposure of a thinly (∼10 Å) oxidized silicon surface to approximately 60 langmuirs of H2 caused the interface-related Auger peak to disappear. This result may be related to the previously demonstrated hydrogen annealing of both interface states and ESR Pb centers at the interface.
Room-temperature 4.6-μm light emitting diodes
Authors: Lo Wayne , Swets Don E.
Published: February 2003

Room-temperature long-wavelength (4.6-μm) light emitting diodes have been fabricated from high quality lead-sulfide-selenide single crystals. Spontaneous emission spectra were used to determine the temperature dependence of the band gap. The result (3.9×10−4 eV/K) is in good agreement with data obtained by others. The bandwidth of the emission is proportional to temperature. These results suggest that thermally broadened band-to-band recombination is the source of electroluminescence.
Effects of ambients on oxygen precipitation in silicon
Authors: Hu S. M.
Published: February 2003

We have discovered an ambient effect on the precipitation of oxygen in the bulk of silicon wafers. Oxidizing ambients were found to strongly retard the precipitation, in comparison with various inert ambients. The precipitation process was studied by the methods of infrared spectrophotometry, thermal conversion, and transmission electron microscopy. In oxidizing ambients, oxygen precipitates tended to cluster in colonies. A typical colony consisted of a few to tens of precipitates, webbed in a complex of dislocation loops. In contrast, precipitates formed in inert ambients were usually isolated. Two mechanisms are suggested to explain this effect, both involving oxidation-generated silicon self-interstitials.
Silicide formation using a scanning cw laser beam
Authors: Shibata T. , Gibbons J. F. , Sigmon T. W.
Published: February 2003

A scanning cw laser has been used to react e-beam-deposited Pd, Pt, and Nb thin films with single-crystal silicon substrates. A single laser scan is capable of reacting 1300 Å of Pd with Si to form either Pd2Si or PdSi, depending on the laser power. Multiple laser scans are necessary to completely react 1100 Å of Nb to form NbSi2. X-ray diffraction analysis shows that the Pd and Nb silicides formed are essentially single phase. The formation of Pd2Si and NbSi2 can be understood by a solid-phase diffusion mechanism. However, it is suggested that a nucleation-reaction-controlled process is occurring in the formation of the PdSi compound. The formation of a superconducting Pt2Si3 is also shown.
Effect of lattice misfit on p
n junction characteristics
Authors: Ito K.
Published: February 2003

Junction diodes of p+ Si1−xGex-n Si (0⩽x⩽0.2) were made by a liquid-phase epitaxial method. A lattice misfit larger than 0.3% present at the junction interface caused an increase of the current density at small forward bias and also a weak voltage dependence of the current at large forward bias. The forward I-V characteristics were explained in terms of carrier recombination generation in the space-charge region of an asymmetrical pn junction.
Proton injection phenomena in WO3-electrolyte electrochromic cells
Authors: Nishimura Tomonori , Taira Kozo , Kurita Shoichi
Published: February 2003

Incorporation of protons from an aqueous solution into WO3 films at the coloration of electrochromic cells has been demonstrated directly by two methods: first by observing coloration from an aqueous anode in planar geometric cells, and second by detecting infrared absorption due to O–D radicals in WO3 previously colored with heavy water.
400-Å linewidth e-beam lithography on thick silicon substrates
Authors: Howard R. E. , Hu E. L. , Jackel L. D. , Grabbe P. , Tennant D. M.
Published: February 2003

Resist features as small as 200 Å and gold lines as narrow as 400 Å separated by 800-Å center to center have been fabricated on thick silicon. substrates. A two-layer electron-sensitive resist structure is employed consisting of an upper layer of polymethyl-methacrylate and a lower layer of a copolymer of methacrylic acid and methyl methacrylate. Use of the more electron-sensitive lower layer results in an undercut which provides clean lift-off of the evaporated gold. Degradation in the pattern resolution by electrons backscattered from the substrate is minimized by the presence of the lower resist layer. This method provides the finest resolution lift-off patterns reported.
The formation of silicides from thin films of some rare-earth metals
Authors: Baglin J. E. , d’Heurle F. M. , Petersson C. S
Published: February 2003

The formation of silicides from thin films of the rare-earth (or related) elements Y, Tb, and Er, on both (100) and (111) Si substrates, has been investigated simultaneously with backscattering and x-ray diffraction. The silicon-rich compounds of the type R-ESi2−n form almost directly with no, or only poorly distinct formation of other silicides at temperatures from about 300 to 500 °C. For all three metals, the reactions with (111) Si require temperatures some 100 °C higher than the reactions with (100) Si, a difference in behavior which is quite important considering the relatively low reaction temperatures. The reactions of Er and Tb with (100) Si are quite sudden, indicating that nucleation is probably the controlling mechanism.
Nonalloyed ohmic contacts to electron-beam-annealed Se-ion-implanted GaAs
Authors: Pianetta P. A. , Stolte C. A. , Hansen J. L.
Published: February 2003

High donor concentrations (n=4×1019 cm−3) have been obtained by pulsed electron beam annealing of Se-ion-implanted GaAs. Nonalloyed ohmic contacts with rc⩽6×10−6 Ω cm2 were formed on these samples with no surface etching. Postanneal heating above 250 °C results in a two-stage loss of carriers.
Surface impurity gradients in epitaxial GaAs
Authors: Nichols K. H. , Goldwasser R. E. , Wolfe C. M.
Published: February 2003

Zero-bias Schottky barrier capacitance measurements indicate the presence of heavily-doped surface impurity gradients in n-type epitaxial layers of GaAs grown on n+ substrates. These impurity gradients are produced during epitaxial growth by the electric field due to 5×1011 cm−2 surface states in GaAs in 1000 K. For n-type layers grown on Cr-doped substrates, high-resistance regions are observed at the surface. These regions are probably caused by the buildup of positively charged chromium atoms in the electric field at the surface. The redistribution of chromium atoms in ion-implanted samples during annealing can also be explained by electric fields due to surface states and the implanted-ion profiles.
Enhanced conductivity in plasma-hydrogenated polysilicon films
Authors: Campbell D. R.
Published: February 2003

Boron-doped polysilicon films have been passivated in a hydrogen plasma. In the range of concentration where carrier transport proceeds by thermionic emission over grain boundary barriers, conductivity enhancements as large as 103 have been observed. The results are ascribed to the removal of dangling-bond carrier traps at grain boundaries by the formation of Si–H bonds.
Field-dependent quantum efficiency in hydrogenated amorphous silicon
Authors: Crandall Richard
Published: February 2003

A model calculation of the electric field dependence of the quantum efficiency for electron-hole pair production in hydrogenated amorphous silicon is presented and compared with recent measurements of the electric field dependence of the solar-cell collection efficiency. The theory, based on electric field reduction of geminate recombination of the excited electron-hole pair, agrees well with experiment.
InGaAsP double heterostructure lasers (λ=1.3 μm) with etched reflectors
Authors: Wright P. D. , Nelson R. J. , Cella T.
Published: February 2003

Discrete InGaAsP double heterostructure lasers (λ=1.3 μm) have been fabricated by a novel batch process which incorporates chemically etched end reflectors. The etched-mirror lasers have threshold current densities as low as 3.5 kA/cm2. The average threshold current density for the etched-mirror lasers is approxiamtely 40% higher than for standard cleaved-mirror devices fabricated from the same wafer. The laser fabrication process permits batch fabrication of a much wider variety of discrete laser geometries than conventional laser-cleaving techniques.
Grating-coupled optical imaging using an acoustoelectric memory correlator
Authors: Wang K. L. , Goll J. H. , Kino G. S.
Published: February 2003

A new method of acoustically scanned optical imaging using a gap-coupled Schottky-diode/LiNbO3 memory correlator is reported. A periodically modulated light intensity pattern is used to create a space-charge grating pattern in the diode array. Image scanning is accomplished by a surface acoustic wave (SAW) propagating on a LiNbO3 delay line. The evanescent rf field accompanying the SAW is coupled to the diode array through a narrow air gap (∼3000 Å). Nonlinear depletion-layer mixing of the electric fields associated with the charge grating and the SAW gives a line scan of the light intensity pattern. Linear imaging has been demonstrated at an optical wavelength of 6328 Å.
Laser photoelectron spectrometry measurement of characteristic electronic and vibrational temperatures of sputtered negative ions
Authors: Corderman Reed R. , Engelking P. C. , Lineberger W. C.
Published: February 2003

The techniques of laser photoelectron spectrometry are used to characterize directly the internal energy distribution of sputtered negative ions. Effective temperatures of Telec≈1500±500 K and Tvib ≈5000±1000 K are determined. The excited electronic and vibrational state populations are not in equilibrium, in contrast to predictions of the local thermodynamic equilibrium model of sputtering.
Liquid-crystal orientational bistability and nematic storage effects
Authors: Boyd G. D. , Cheng Julian , Ngo P. D. T.
Published: February 2003

A new class of nematic liquid-crystal storage effects with potential display applications is described. We have developed structures, produced by special surface alignment patterns, exhibiting bistable configurations. Switching between states has been demonstrated with both electric and magnetic fields. The movement of disclinations and the topological distinction between states play essential roles in bistable switching. The properties of the bistable states and a proposed switching mechanism are described.
A planar electro-optic prism array beam splitter
Authors: Huang J. Y. , Lee C. L.
Published: February 2003

A new type of planar electro-optic prism array is presented. The array is composed of an individual pair of prisms that gives a sawtooth phase shift to the wave front of the transmitted optical beam; thus the array acts as a triangular phase grating. Theoretical analysis as well as experimental work show that the array behaves as a beam splitter. The splitting of the beam is voltage controllable.
Optically pumped superfluorescence S2 molecular laser
Authors: Girardeau-Montaut J. P. , Moreau G.
Published: February 2003

Superfluorescent laser emission has been achieved on the B3Σ−u(v′=2) −X3Σ−g(v″=7–18) transitions of the S2 molecule by resonant optical pumping at 337.1 nm with a nitrogen laser. It was observed on a series of ten near-ultraviolet and visible lines from 370 to 490 nm with a mean induced gas near 0.05 cm−1. Discussion of pulsed laser operation including data on spectroscopic and dynamical processes is reported.
Efficient waveguide electro-optic TE⇄TM mode converter/wavelength filter
Authors: Alferness R. C.
Published: February 2003

We report the first demonstration of efficient phase-matched waveguide electro-optic polarization conversion. Using a strip Ti-diffused lithium niobate waveguide and periodic electrodes, we have achieved TE⇄TM conversion efficiency in excess of 99% with an applied voltage of 13 V. The conversion efficiency is strongly wavelength selective; filter bandwidths between 4.5 and 15 Å have been obtained.
Blazed dielectric gratings with high beam-coupling efficiencies
Authors: Gruss A. , Tam K. T. , Tamir T.
Published: February 2003

By using microwave models of optical gratings, we have realized dielectric gratings with asymmetric triangular or trapezoidal profiles that exhibit beam-coupling efficiencies in excess of 90% over wide ranges of frequencies and grating parameters. These desirable properties are consistent with the behavior predicted by a Bragg scattering analysis of the grating operation, as well as with numerical data provided by an exact solution.
Multistate amorphous-semiconductor switch
Authors: Coldren L. A. , Bösch M. A. , Rentschler J. A.
Published: February 2003

A chalcogenide threshold switching device with three stable states that can be influenced by a third electrode or light is described. The threshold voltage as well as the conductance of one of the on-states can be varied significantly in this way. Although the actual device was fabricated on crystalline Si, the results suggest that an analogous all thin-film structure should be possible.
Origin of reverse annealing in radiation-damaged silicon solar cells
Authors: Weinberg I. , Swartz C. K.
Published: February 2003

Relative defect concentrations, energy levels, capture cross sections, and minority carrier diffusion lengths are used to identify the defect responsible for the reverse annealing observed in a radiation-damaged n+/p silicon solar cell. The responsible defect, with energy level at Ev+0.30 eV, has been tentatively identified as a boron-oxygen-vacancy complex. It is shown tht removal of this defect could result in significant cell recovery when annealing at temperatures well below the currently required 400 °C.
Electron drift mobility in hydrogenated a-Si
Authors: Tiedje T. , Abeles B. , Morel D. L. , Moustakas T. D. , Wronski C. R.
Published: February 2003

The electron drift mobility μd was measured in hydrogenated a-Si films prepared by rf and dc glow discharge in silane and by reactive sputtering in an Ar-H2 gas mixture. The electron transport in the glow-discharge material was found to be nondispersive. The highest observed room-temperature drift mobility, 0.8 cm2/V  s, is a factor of 8 higher than previously reported. An electron drift mobility of 0.05 cm2/V s was observed in the sputtered material.
Critical currents in A-15 structure Nb3Al converted from cold-worked bcc structure
Authors: Woollam John A. , Alterovitz Samuel A. , Haugland Edward , Webb George W.
Published: February 2003

Nb3Al prepared in the ductile bcc phase by quenching, followed by mechanical working, followed by conversion to the A-15 structure is found to carry currents above 109 A/m2 in fields near 20 T. These critical currents are comparable to those found in Nb3Ge and V3Ga, the closest competing materials for use in high fields. Further enhancement of Jc is possible if thermal treatments are optimized.
Enrichment of deuterium using vibrationally sensitized reaction of methane
Authors: Hsu D. S. Y. , Manuccia T. J.
Published: February 2003

V V energy transfer from cw-CO2-laser-pumped CO2 molecules preferentially excites deuterated methane (CH2D2 or CH3D) in mixtures with CH4. This isotopically selective energy transfer in combination with competing deactivation processes results in a steady state in which the deuterated species remain more highly excited than the nondeuterated species. Subsequent endothermic reactions of the methanes with bromine atoms preferentially form the deuterium-containing stable products, various methyl bromides, and hydrogen bromide. For the CH2D2 mixture, deuterium enrichment of up to 300% (i.e., an enrichment factor of 4.0) has been obtained, whereas for the CH3D-CH4 mixture, under less favorable conditions, an 83% enrichment has been observed. The advantages of the selective energy transfer technique and the endothermic reaction system will be discussed.
UV picosecond pulse amplification by a XeCl laser
Authors: Maeda Mitsuo , Mizunami Toru , Sato Akio , Uchino Osamu , Miyazoe Yasushi
Published: February 2003

A UV-preionized discharge-pumped XeCl excimer laser effectively amplified the frequency-doubled picosecond (3–4 ps) pulses generated by a passively mode-locked flashlamp-pumped rhodamine 6G dye laser tuned to the 308-nm band. The peak power of the amplified pulse is 710 MW, and the net power gain is 151. The proposed scheme is promising for the construction of a scalable high-power ultrashort-pulse generator in the UV region.
High-power ion beam generation with an inverse reflex tetrode
Authors: Pasour J. A. , Mahaffey R. A. , Golden J. , Kapetanakos C. A.
Published: February 2003

A new reflexing-electron ion source is described. The device produces a unidirectional ion beam with relatively high efficiency even when the applied magnetic field exceeds the self-field. This new source operates at a low, constant impedance during much of the applied voltage pulse and is better matched to available high-power, low-impedance generators than previous reflexing-electron devices. Proton pulses with peak current ∼500 kA have been produced with the inverse reflex tetrode coupled to the Gamble II generator.
Effects of the beamfront velocity on collective acceleration with relativistic electron beams
Authors: Spector D. N. , Gerber K. A. , Mahaffey R. A. , Meger R. A. , Sethian J. D.
Published: February 2003

Observations of accelerated protons during the injection of rotating relativistic electron beams into neutral hydrogen (50–400 mTorr) indicate that ions from the beam-formed plasma are trapped and accelerated by a potential well at the beamfront. Measurements show that the number of accelerated protons decreases as the beamfront velocity is increased. Moreover, at a given velocity, the number accelerated is relatively insensitive to the neutral gas pressure.
Reduction of saucer pit microdefects in epitaxial silicon wafer by intrinsic gettering
Authors: Tsuya Hideki , Tanno Kohetsu , Shimura Fumio
Published: February 2003

The reduction of microdefects in epitaxial silicon wafers is achieved by a two-step annealing consisting of dry O2 and wet O2 heat treatments based on intrinsic gettering. The gettering mechanism is investigated by means of infrared absorption, an etching procedure, and transmission electron microscopy. It has been found that inner defects which are correlated with the gettering action after the second annealing are classified into three groups depending on the first annealing temperatures from 700 to 1050 °C, that is, small stacking faults, cristobalites, and climbing dislocations are dominant in samples annealed at ≲800, 800∼900, and ≳900 °C, respectively. The depth of the denuded zone is also discussed.
Simple metal-vapor recombination lasers using segmented plasma excitation
Authors: Silfvast W. T. , Szeto L. H. , Wood O. R.
Published: February 2003

A new type of electrically excited laser device has been developed using a new pumping scheme which involves segmented plasma excitation and recombination (SPER). SPER laser action is produced in a metal species when a series of small vaporized plasmas, formed in the gaps between a row of metal electrodes subjected to a high-voltage pulse, is allowed to expand and recombine. To date, laser action at 17 wavelengths between 0.94 and 1.84 μm in 8 metal vapors has been observed. This device is simple to construct, has a long operating life, and has the potential for high efficiency.
60-ns E-beam excitation of rare-gas halide lasers
Authors: Edwards C. B. , O’Neill F. , Shaw M. J.
Published: February 2003

We have measured the intrinsic efficiency of ArF, KrF, XeCl, and XeF lasers using 60-ns e-beam pumping at an excitation rate of 1.5 MW/cm3. Efficiencies between 3 and 11% have been obtained. These values are shown to be limited by the time required to build up oscillation in the laser cavity, and we have demonstrated a technique which can be used to overcome this problem. Peak power efficiencies of these lasers are calculated to be in the range 5–15%.
A picosecond jitter streak camera
Authors: Mourou G. , Knox W.
Published: February 2003

A light-activated silicon switch is used to sweep a picosecond-resolution streak camera with less than 2 ps of shot-to-shot zero-time fluctuation. This temporal accuracy allows shot accumulation leading to increased signal-to-noise ratio and further increase in timing accuracy. Subpicosecond accuracy is demonstrated and is used to time picosecond transients.
Whispering gallery lasers on semi-insulating GaAs substrates
Authors: Ury I. , Margalit S. , Bar-Chaim N. , Yust M. , Wilt D. , Yariv A.
Published: February 2003

Double heterostructure lasers are described in which light is guided by total internal reflection along a dielectric interface formed by the perimeter of an etched mesa. By means of the crowding effect, injection current is restricted to a narrow strip adjacent to the edge of the mesa. This results in the preferential excitation of optical modes which are localized in the vicinity of the dielectric interface. Both half-ring lasers formed at a single cleaved facet and quarter-ring lasers formed at a cleaved corner were fabricated.
Growth of thin silicon films on sapphire and spinel by molecular beam epitaxy
Authors: Bean J. C.
Published: February 2003

Epitaxial silicon films have been grown by molecular beam epitaxy (MBE) on (1̄012) sapphire and (100) spinel substrates. Film morphology and electrical quality are strong functions of substrate preparation and vacuum purity. Under optimized conditions, single-crystal growth occurs at 650–800 °C and 700–900 °C on sapphire and spinel substrates, respectively. Films initially grow in islands which coalesce and gradually form smooth continuous layers. On sapphire, coalescence occurs at ∼500 Å and films grow smoothly above ∼2000 Å. On spinel coalescence occurs at ∼0.5 μm and smooth growth above ∼1 μm. Thick films on either substrate have mobilities close to bulk. As thickness decreases, mobilities fall gradually and values cannot be measured in films less than twice the coalescence thickness. At thicknesses of 0.5 and 1.0 μm, MBE SOS films have mobilities in excess of those reported for comparably doped CVD layers.
Steady-state thermally annealed GaAs with room-temperature-implanted Si
Authors: Masuyama A. , Nicolet M.-A. , Golecki I. , Tandon J. L. , Sadana D. K. , Washburn J.
Published: February 2003

Semi-insulating Cr-doped single-crystal GaAs samples were implanted at room temperature with 300-keV Si ions in the dose range of (0.17–2.0)×1015 cm−2 and were subsequently steady-state annealed at 900 and 950 °C for 30 min in a H2 ambient with a Si3N4 coating. Differential Hall measurements showed that an upper threshold of about 2×1018/cm3 exists for the free-electron concentration. The as-implanted atomic-Si profile measured by SIMS follows the theoretical prediction, but is altered during annealing. The Cr distribution also changes, and a band of dislocation loops ∼2–3 kÅ wide is revealed by cross-sectional TEM at a mean depth of Rp∼3 kÅ. Incomplete electrical activation of the Si is shown to be the primary cause for the effect.
Electron dynamics in nearly pinched-off GaAs field effect transistor operation
Authors: Deblock M. , Fauquembergue R. , Constant E. , Boittiaux B.
Published: February 2003

Using a simplified Monte Carlo simulation of a transverse section of a GaAs field effect transistor, it is shown that for nearly pinched-off operation, electron dynamics strongly depends on the transverse electric field acting on the electrons and also that the classical theoretical treatment based on the electron velocity equations cannot be used to take this effect into account.
Determination of substitutional dopant and hole concentrations in Zn-diffused single-crystal InP
Authors: Williams R. S. , Barnes P. A. , Feldman L. C.
Published: February 2003

Proton-induced x-ray emission combined with channeling techniques has been used to evaluate Zn-diffused InP crystals. The measurements showed that the total Zn concentration was (1.00.3)×1019/cm3 with 505% of the dopant residing on lattice sites for samples prepared by sealed-ampoule diffusion at 700 °C with a P overpressure. Hall measurements yielded a hole concentration of (5.00.5)×1018/cm3, indicating that most of the substitutional Zn in InP is electrically active and not associated in neutral substitutional complexes as previously suggested. Fine precipitates observed by transmission electron microscopy are assumed to contain the nonsubstitutional Zn.
Backside-illuminated InAsSb/GaSb broadband detectors
Authors: Bubulac L. O. , Andrews A. M. , Gertner E. R. , Cheung D. T.
Published: February 2003

This letter reports the achievement of a high-performance, broad-spectral-band infrared detector with the InAs1−xSbx alloy system using a backside-illuminated heterostructure approach. The basic structure of the detector is obtained with InAs1−xSbx grown by a liquid phase epitaxy technique on a GaSb substrate under lattice-matched or nearly lattice-matched conditions. The measured photoresponse covers the spectral range 1.7–4.2 μm with an external quantum efficiency of 65% without antireflective coating. The typical zero-bias resistance area product is in excess of 109 Ω cm2. The typical leakage current desity is less than 10−9 A/cm2 for 100 mV reverse bias. All parameters were measured at 77 K.
Selective etching of Si relative to SiO2 without undercutting by CBrF3 plasma
Authors: Matsuo Seitaro
Published: February 2003

Etching characteristics with selectivity similar to conventional CF4 plasma etching but without undercutting are realized by plasma-reactive sputter etching, based on the reactivity of the incident ions combining fluorocarbons with low reactive halogens. In particular, the method with CBrF3 is practically useful for selective etching of Si, poly-Si, and Mo relative to SiO2 in high-accuracy pattern transfer.
Josephson behavior in granular NbN weak links
Authors: Claassen J. H.
Published: February 2003

A substrate step technique has been used to fabricate superconducting NbN weak links of length ∼750 Å, width ∼1.5 μm. The film in the weak-link region is less than 100 Å thick, and shows evidence of being granular. These devices have very high resistance (as much as 30 Ω), are quite rugged, and show almost ideal Josephson response to microwave radiation at 70 GHz. A vortex flow model is expected to apply because of the small coherence length in the weak-link material. However, the well-known resistively shunted junction model is found to be a significantly better predictor of device behavior.
Photoacoustic microscopy of an integrated circuit
Authors: Favro L. D. , Kuo P. K. , Pouch J. J. , Thomas R. L.
Published: February 2003

The in-phase and quadrature components of a photoacoustic signal have been used to form images of an integrated circuit with ∼6 μm resolution. These photoacoustic images contain information about subsurface properties of the sample.
Generation and measurement of ultrashort current pulses with Josephson devices
Authors: Faris Sadeg M.
Published: February 2003

Experimental demonstration of an ultrashort-pulse generator and a novel sampling technique to measure its pulse shape is reported. The pulse generator, which uses Josephson interferometers, is designed to be dc powered and self-resetting. Its pulses are measured to be 26 ps in duration at a simulated maximum frequency of 2.5 GHz. The sampling technique is useful for measuring general fast waveforms with unprecented sensitivity and resolution extendable to subpicosecond time scale.
Multiple-pulse thermal coupling at 3.8-μm wavelength
Authors: Maher W. E. , Nichols D. B. , Hall R. B.
Published: February 2003

Pulsed DF laser irradiation of 2024-T3 aluminum in normal air produced increases in air-plasma-enhanced energy absorption after repeated exposures of the same target. For a sequence of pulses, the absorbed fluence per pulse increased on each shot until it reached a value more than twice that seen on the first pulse. The effect is believed to be due to surface roughening caused by melting and vaporization.
High-temperature cw operation of GaInAsP/InP lasers emitting at 1.5 μm
Authors: Hsieh J. J.
Published: February 2003

cw operation at temperatures up to 55 °C has been achieved for GaInAsP/InP double-heterostructure lasers emitting at 1.5 μm which were grown without a GaInAsP buffer layer.
A new plasma source, the plasma emitter
Authors: Saeki K. , Iizuka S. , Sato N. , Hatta Y.
Published: February 2003

A new plasma source, the ’’plasma emitter,’’ was successfully developed by using thermionic plasma emission from a mixture of aluminosilicate and barium oxide. At an operating temperature around 1300 K, we have a plasma of density 1×107–2×108 cm−3 and temperature ≃0.16 eV. The plasma emitter, being quite simple in its construction and especially cheap, is very useful for various kinds of plasma experiments and applications.
Kirkendall void formation in thin-film diffusion couples
Authors: Nakahara S. , McCoy R. J.
Published: February 2003

Transmission electron microscope studies of Sn/Au thin-film couples reveal complexities associated with the Kirkendall effect in thin films. The use of an offset film fabrication technique permitted the identification of two room-temperature interdiffusion mechanisms in Sn/Au: grain-boundary diffusion of Sn into Au, which causes film thinning, and bulk diffusion of Au into Sn, which results in the formation of microscopic Kirkendall voids. The ranges of importance of the two mechanisms were explored by varying the Sn and Au film thicknesses and the grain size. It is pointed out that interdiffusion studies in thin films required careful attention to relative film thicknesses, film geometry, and grain sizes in order to determine the fast-diffusing species and the operative diffusion mechanisms.
Bandwidth-limited picosecond pulse generation in an actively mode-locked GaAlAs diode laser
Authors: Holbrook M. B. , Sleat W. E. , Bradley D. J.
Published: February 2003

Bandwidth-limited pulses of 16 ps duration, 1W peak power, and a time-bandwidth product value of ΔνΔt=0.36 are obtained from an actively mode-locked, angled-stripe GaAlAs cw diode laser. A synchronized streak camera measures the pulse durations and allows continuous monitoring and optimization of the mode locking process.
Anodic oxidation of InGaAsP
Authors: Law H. D.
Published: February 2003

Anodic oxides were successfully grown on n-InGaAsP liquid phase epitaxial layers by 0.1-M ammonium phosphate dibasic solution at current density of 0.2 mA/cm2. The as-grown oxide was extremely uniform. The refractive indices of the grown quaternary oxide were found to be in the range of 1.6–1.75. The relationship of the oxide thickness to the cell voltage was linear with the slope of approximately 22 Å/V, not counting the initial cell voltage. The breakdown field of the oxide was around 3×106 V/cm. The anodization process on an epitaxial layer can be used to evaluate epitaxial layer quality. The process can also be used to ’’patch’’ up all the leaky spots of a diode.
Metastable phases in laser-irradiated Pt-Si and Pd-Si thin films
Authors: von Allmen M. , Lau S. S. , Mäenpää M. , Tsaur B. Y.
Published: February 2003

Amorphous phases of Pt-Si and Pd-Si covering a wide range of compositions are produced by laser-induced melting and quenching of vapor-deposited thin films. It is concluded that with the present cooling rates all compositions except those close to the congruently melting phases and the pure elements lead to amorphous films. Thermal decomposition of the Si-rich amorphous films reveals the formations of at least two metastable crystalline phases in the case of Pt-Si, and a low-temperature nucleation of the equilibrium PdSi phase in the case of Pd-Si.
Internal photoemission in hydrogenated amorphous-Si films
Authors: Wronski C. R. , Abeles B. , Cody G. D. , Tiedje T.
Published: February 2003

Measurements of internal photoemission from metal contacts into amorphous SiHx are reported. The height of the barriers at Cr, Pd, and Pt contacts were found to be 0.83, 0.98, and 1.12 eV, respectively, from the photoemission threshold.
Optoacoustic determination of photocarrier generation efficiencies of dye films
Authors: Tam A. C.
Published: February 2003

An optoacoustic method is used for the first time to study photoconductive efficiencies of thin dye films coated on a substrate. A piezoelectric transducer is attached to the substrate, and the dye film is excited by a modulated cw laser beam, of intensity less than 0.1 mW/cm2. Strong signal enhancement occurs when the laser modulation frequency is equal to a fundamental mechanical resonance frequency of the sample-transducer assembly (about 40 kHz in our experiment). The quantum efficiency for photocarrier generation is derived by measuring the decrease in optoacoustic signal when an electric field is applied to the sample.
Diffraction-grating-enhanced light emission from tunnel junctions
Authors: Kirtley J. R. , Theis T. N. , Tsang J. C.
Published: February 2003

We report the observation of highly polarized, angle-tunable visible light emission from Al-AlOx-Ag tunnel junctions fabricated on holographic gratings. From the angular dependence of the emission frequency we identify the electromagnetic mode responsible for the emission. The mode is surface plasmonlike with a dispersion that closely follows the light line. This is in contrast to the much lower phase velocity ’’junction’’ mode believed responsible for the light emission on surface-roughened tunnel junctions. We argue that both modes should be considered in describing the emission from these devices.
Pulsed laser irradiation of lead-implanted single-crystal copper films
Authors: Rimini E. , Baglin J. E. E.
Published: February 2003

We have studied the effect of pulsed laser annealing on single-crystal copper films implanted with lead to a concentration far in excess of equilibrium solid solubility. A Nd:YAG frequency-doubled 50-ns-pulsed laser was used, with power density up to 2.4 J/cm2. Channeling of 2-MeV helium ions was used to determine the concentration profile and degree of substitutionality of the lead both before and after laser irradiation. The near-surface region is melted if irradiated with a laser pulse of adequate energy density. The Pb atoms are redistributed and some accumulate near the sample surface. The fraction of Pb atoms which remain substitutional is nearly the same for as-implanted and laser-irradiated samples. This indicates that the rapid quenching following laser annealing (∼1011 K/sec) is almost as effective in retaining Pb atoms in metastable solution in Cu as the original effective quenching (∼1014 K/sec) following Pb implantation. Furnace annealing at 250 °C for 30 min greatly reduces the substitutional fraction of Pb atoms, as expected.
High-performance backside-illuminated Hg0.78Cd0.22Te/CdTe (λCO=10 μm) planar diodes
Authors: Chu M. , Vanderwyck A. H. B. , Cheung D. T.
Published: February 2003

Planar infrared photodiodes have been fabricated on Hg1−xCdxTe (x=0.22) epitaxial layers which were grown on CdTe substrates by the liquid phase epitaxy technique. The n+-p junctions were formed by ion implantation. The R0A products of the diodes have been measured to be ∼105 Ω cm2 at 40 K and ∼107 Ω cm2 at 20 K. These R0A values are believed to be the highest ever reported for HgCdTe photodiodes with comparable cutoff wavelengths. It was found that between 77 and 40 K the diode R0A was limited by generation-recombination current. Effects of field plate bias on diode properties were also analyzed.
Single-growth embedded epitaxy AlGaAs injection lasers with extremely low threshold currents
Authors: Katz J. , Margalit S. , Wilt D. , Chen P. C. , Yariv A.
Published: February 2003

A new type of strip-geometry AlGaAs double-heterostructure laser with an embedded optical waveguide has been developed. The new structure is fabricated using a single step of epitaxial growth. Lasers with threshold currents as low as 9.5 mA (150 μm long) were obtained. These lasers exhibit operation in a single spatial and longitudinal mode, have differential quantum efficiencies exceeding 45%, and a characteristic temperature of 175° C. They emit more than 12 mW/facet of optical power without any kinks.
Direct observation of laser-induced solid-phase epitaxial crystallization by time-resolved optical reflectivity
Authors: Olson G. L. , Kokorowski S. A. , McFarlane R. A. , Hess L. D.
Published: February 2003

Direct measurement of solid phase epitaxial crystallization during cw laser annealing of ion-implanted silicon is reported. The measurement technique utilizes optical interference effects between reflected light from the sample surface and from the epitaxial growth plane to time-resolve the growth process with high spatial resolution. Laser-induced solid phase epitaxial growth was monitored for two values of incident laser power; corresponding epitaxial growth rates and calculated surface temperatures are given.
Reactive-ion etching of GaAs and InP using CCl2F2/Ar/O2
Authors: Hu E. L. , Howard R. E.
Published: February 2003

We describe the reactive ion etching of GaAs, InP, and their derivative compounds using an etch gas composed of CCl2F2, O2, and argon. Etching was generally carried out at pressures between 1 and 10 μ, and power densities below 0.8 W/cm2. Clean etch profiles were obtained with etch rates as high as 0.25 μm/min. A strong dependence of etch rate on pressure was observed with a maximum at 5 μ total pressure. The etch profiles exhibited a ’’negative undercut’’ character which was also dependent upon the total pressure.
Scanned electron beam annealing of arsenic-implanted silicon
Authors: Smith H. J. , Ligeon E. , Bontemps A.
Published: February 2003

A scanning electron beam system for the annealing of ion-implanted solids is described. Annealing of 〈100〉 silicon implanted with arsenic (120 keV, 3×1015 As/cm2) was investigated. Analysis by 1.2-MeV 4He channeling allowed the detailed monitoring of the recrystallization process, which occurs by means of a solid-phase mechanism. The role of the various parameters such as electron beam power and application time has been explored.
Direct solid-state precipitation-processed A15 (Nb3A1) superconducting material
Authors: Hong M. , Morris J. W.
Published: February 2003

A ’’solid-state precipitation’’ process was used to prepare superconducting tapes containing Nb3Al in a niobium matrix. Small ingots of Nb–(17–19 at . %)Al were prepared by arc melting, homogenizing, quenching, warm rolling into tape, and aging at 750–900°C to precipitate the A15 phase. Transmission electron microscopy studies revealed Nb3Al precipitation in fine particles which formed a semicontinuous network over subgrain boundaries fromed by the recovery of deformation-induced dislocations. Promising high-field critical currents were obtained (Jc∼104 A/cm2 in a field of 14 T at 4.2 K).
High-speed laser modulation with integrated optical injection
Authors: Fekete D. , Streifer W. , Scifres D. R. , Burnham R. D.
Published: February 2003

We report operation of an integrated diode laser device, which utilizes light injected from a pump curved waveguide branch terminated by a reflecting facet to provide feedback. This waveguide geometry eliminates relaxation oscillations while simultaneously decreasing the response time of the laser to pulsed current modulation. Randomly timed pulses as short as 250 psec duration are observed and this value results from limitations of the electronics and not the laser. An analysis indicates the roles of the various parameters.
Ionic conductivity of single-crystal Na5YSi4O12
Authors: Beyeler H. U. , Shannon R. D. , Chen H. Y.
Published: February 2003

We have investigated the single-crystal ionic conductivity of Na5YSi4O12. The conductivity is found to exhibit a thermally activated temperature dependence between 200 and 500 K with activation energies of 0.221 and 0.203 eV parallel and perpendicular to the hexagonal c axis. Room-temperature conductivities were determined to be 0.0032 and 0.008 (Ω cm)−1.
Symmetry of the Au (110) surface reconstruction studied by spin-polarized low-energy electron diffraction
Authors: Reihl B. , Dunlap B. I.
Published: February 2003

Spin-polarized low-energy electron diffraction measurements of the analyzing power of two specular beams and the (0, 1/2 ) beam are presented. A theoretial argument relates the analyzing power S and polarizing power P of these beams for an unreconstructed Au (110) surface. This is used to deduce the symmetry of the reconstructed surface. In particualr, these results are inconsistent with the missing- and pairing-row models, suggesting rotation within the reconstructed unit cell.
High-frequency noise in weakly inverted metal-oxide-semiconductor transistors
Authors: Liu S. T. , van der Ziel A.
Published: February 2003

The high-frequency noise in weakly inverted metal-oxide-semiconductor field-effect transistors is identified experimentally as the thermal noise associated with the diffusion current flowing from source to drain. In terms of the saturated diode current, the equivalent noise current Ieq is shown to be proportional to the drain current. In some cases the proportionality constant to unity and the thermal noise behavior resembles shot noise behavior.
Multiline (480–496 nm) discharge-pumped iodine monofluoride laser
Authors: Dlabal M. L. , Hutchinson S. B. , Eden J. G. , Verdeyen J. T.
Published: February 2003

Lasing at 478.7, 484.7, 490.7, and 496.5 nm has been observed on the E→A3Π (bound→bound) band of the IF (iodine monofluoride) molecule in discharge-pumped He, Ar, CF3I, and NF3 gas mixtures. Oscillation was obtained using a stable optical cavity with output coupling mirror transmissions of 0.2 and 92%. For a 99.7%-He, 0.2%-NF3, and 0.1%-CF3I (ptotal≈1540 Torr) gas mixture and T∼92% (quartz flat), output pulse energies of ∼0.35 mJ in a ∼15-ns FWHM pulse (peak output power ≳24 kW) were measured. Optimization of the cavity output coupling and increased Ar pressures in conjunction with the use of an attaching gas (to raise the discharge E/N) are expected to improve the output energy and, consequently, the overall efficiency of this blue-green laser.