bluuebunny/crossref_metadata_2025 huggingface dataset:
Plastic deformation and fracture resulting from stresses caused by differential thermal contraction in GaP/Si heterostructures
Authors: Tsui R. K. , Gershenzon M.
Published: February 2003

Cleavage cracks form in thick (≳5 μm) GaP layers deposited epitaxially on Si during the cooldown after growth. The distribution of stresses caused by differential thermal contraction in such heterostructures has been analyzed, and suggests that stress relief through plastic deformation explains why GaP layers thinner than 5 μm do not crack. Large-area, crack-free layers thicker than 5 μm have been grown on Si-on-sapphire substrates because the resultant stresses in the GaP layers are compressive rather than tensile.
On the comparison of transmission electron microscopy and channeled Rutherford backscattering techniques to evaluate the multilayer subsurface damage structures
Authors: Sadana D. K. , Strathman M. , Washburn J. , Booker G. R.
Published: February 2003

Cross-sectional transmission electron microscopy (TEM) and MeV He+ channeling methods have been used to examine different damage structures present under the color bands visible at the surface of a high-dose-rate P+-implanted (111) Si wafer implanted to a dose of 7.5×1015 ions/cm2. TEM and channeling results obtained from individual colored regions showed a good qualitative correlation in that discrete damage layers observed in the cross-sectional TEM micrographs appeared as discrete peaks in the channeled spectra. The mean depths of the damage layers obtained from these two methods were in agreement. However, the widths of the deeper-lying damage layers calculated from the channeling measurements were always greater than the widths observed by TEM. An empirical method based on subtraction of dechanneling background in the channeling spectra gave damage layer widths that were in close agreement with the TEM results.
Josephson junctions of small area formed on the edges of niobium films
Authors: Broom R. F. , Oosenbrug A. , Walter W.
Published: February 2003

Niobium-oxide-lead Josephson tunnel junctions formed on the edge of the Nb base electrode are found to have excellent tunnel characteristics up to Josephson current densities of at least 20 kA/cm2. They are made by growing an anodic oxide several hundred angstroms in thickness on the Nb followed by plasma etching of the sandwich using CF4+O2. Only the exposed edges of the Nb films are subsequently oxidized to form the tunnel barrier. Preliminary results show uniform and reproducible Josephson currents, with no evidence of leakage through the surface oxide. The structures combine small capacitance, a well-defined area, and the ability to pattern large arrays of junctions and interferometers, properties which make them attractive for cyrogenic computers and other high-frequency applications.
Resonances in symmetric Josephson interferometers
Authors: Tuckerman David B. , Magerlein J. H.
Published: February 2003

A simple analytical theory is presented which calculates the current due to self-induced resonances in symmetric two-junction Josephson interferometers as a function of voltage, control current, and damping. Experimental measurements of interferometer I-V curves near a resonance and of peak resonance amplitudes as a function of control current were carried out and found to agree with the theory. The existence of a negative-resistance region in the I-V curves of lightly damped, current-biased interferometers is predicted and experimentally verified. The theory allows accurate determination of the resonant voltage and the interferometer damping from experimental I-V curves.
A new mechanism for high-frequency rectification at low temperatures in point contacts between identical metals
Authors: van der Heijden R. W. , Jansen A. G. M. , Stoelinga J. H. M. , Swartjes H. M. , Wyder P.
Published: February 2003

Experimental results are reported of high-frequency (∼ THz) radiation detection by metal-metal point contacts at low temperatures as a function of bias voltage. The dominant detection mechanism can be attributed to rectification due to electron-phonon-scattering-induced nonlinearity of the I-V characteristics, a process not observed before.
High-power laser discharge stabilization with magnetic fields
Authors: Seguin H. J. J. , Capjack C. E. , Antoniuk D. , Nam K. A.
Published: February 2003

A new discharge stabilization technique for high-powered gas lasers is described. Profiled magnetic fields interacting with electron and ion sheaths at or near the electrode surfaces inhibit growth of electrothermal plasma instabilities and increase power loading by an order of magnitude. The technique appears to be scalable for very-large-volume devices.
Incoherent-light-flash annealing of phosphorus-implanted silicon
Authors: Correra L. , Pedulli L.
Published: February 2003

Incoherent light pulses emitted from a xenon flash lamp were used to anneal radiation damage in (100) silicon implanted with 2×1015 31P+/cm2 at 100 keV. Electrical carrier concentration has been determined by means of differential sheet resistivity and Hall effect together with the anodic oxidation stripping technique; the surface photovoltage technique has been used to evaluate bulk lifetime and Rutherford backscattering and transmission electron microscopy for analysis of radiation damage. Damage recovery appears to take place via a solid phase epitaxial process. Electrical activity and carrier mobility values of samples annealed by incoherent light are similar to those obtained by laser, electron beam, and furnace annealing. The bulk lifetime of minority carriers is not degraded.
Tuning fork resonator using modified PbTiO3 ceramics
Authors: Takeuchi Hiroshi , Jyomura Shigeru
Published: February 2003

Tuning fork resonators with very low temperature coefficients of resonance frequency were fabricated using modified PbTiO3 ceramics. The chemical formula of these ceramics is (Pb1−(3/2)x+(1/2)z Ndx) (Ti1−y−z) Mny Inz) 03. The temperature coefficient can be reduced to −2×10−6/°C at room temperature and zero at 0 °C with the composition x=0.11, y=0.02, and z=0.09. The resonance frequency of the resonators is about 30 kHz and the quality factor is 1100 at the composition. These resonators have potential for low-frequency applications such as oscillators for watches.
Epitaxial growth of Si deposited on (100) Si
Authors: Hung L. S. , Lau S. S. , von Allmen M. , Mayer J. W. , Ullrich B. M. , Baker J. E. , Williams P. , Tseng W. F.
Published: February 2003

Epitaxial growth of deposited amorphous Si on chemically cleaned (100) Si has been found and layer-by-layer growth occurred at rates comparable to those in self-ion-implanted-amorphous Si. There is no evidence for appreciable oxygen penetration into the deposited layer during storage in air. The critical factors in achieving epitaxial growth are fast (∼50 Å/sec) deposition of Si onto a surface cleaned with a HF dip as a last rinse before loading into the vacuum system. Channeling and transmission electron microscopy measurements indicated that the epitaxial layers are essentially defect free. Secondary-ion mass spectroscopic analysis showed about 1014 oxygen/cm2 at the amorphous/crystal interface. With either higher interfacial oxygen coverage or slow (∼2 Å/sec) deposition, epitaxial growth rates are significantly slower.
Ion-beam-induced modification of silicide formation in rare-earth metals: Er-Si and Tb-Si systems
Authors: Tsaur B. Y. , Hung L. S.
Published: February 2003

Interfacial reactions between thin rare-earth metal (Er and Tb) films and crystal Si substrates can be drastically modified by ion implantation. With a low-dose (∼1014 cm−2) Xe ion bombardment through the Er (Tb) film, a well-defined silicide phase grown in a layer-by-layer fasion is observed after postimplantation annealing at ∼300 °C. The rate of growth is parabolic in time with activation energies of 1.71 and 1.25 eV for the Er and Tb silicides, respectively. These results are distinctly different from those observed in unimplanted samples where silicide formation requires somewhat higher temperatures (∼350 °C) and exhibits no evidences of layer-by-layer growth. The effect of ion bombardment on the metal-Si interface and its influences on compound formation are discussed.
Raman scattering study of the thermal oxidation of InP
Authors: Schwartz G. P. , Sunder W. A. , Griffiths J. E.
Published: February 2003

Reflection Raman scattering has been used to study thermally grown air-oxidized films on InP. Elemental red phosphorus is detected in films grown between 350 and 550 °C. At oxidation temperatures exceeding 550 °C, InPO4 is observed with some In2O3 also present as a minor film constituent.
An atomic-fluorine laser pumped by charge transfer from He+2 at high pressures
Authors: Collins C. B. , Lee F. W. , Carroll J. M.
Published: February 2003

Scalable laser output at high powers has been obtained from the quartet system of atomic fluorine when excited by charge transfer from He+2 in a traveling-wave discharge.
Photosensitivity effect in optical fibers: A model for the growth of an interference filter
Authors: Bures J. , Lapierre J. , Pascale D.
Published: February 2003

A photosensitive property of short-length single-mode optical fibers has been shown to produce a periodical modification of the refractive index of the core when exposed to high-intensity laser light. Using a model derived from the coupled-mode theory, we calculate the space-time variation of the interaction between two waves traveling in opposing directions that are responsible for the formation of an interference filter along the axis of the fiber. Our proposed model for the formation and growth of the filter is in good agreement with experiments; a characteristic photosensitivity coefficient is deduced.
Improved excitation by triple discharge in a wire-triggered transverse electric atmospheric CO2 laser
Authors: Lee I. W. , Lee S. S.
Published: February 2003

The output performance of the wire-preionized transverse electric atmospheric CO2 laser is greatly enhanced when increased preionization is accomplished through a triple-discharge technique. Stable TEM00 mode oscillation of the laser is observed in the CO2:N2:He 1:1:1 mixture with input energy density of 240 J/l. The role of the second preionization becomes more significant for the higher charging voltages and for the gas mixtures containing less helium.
High-electric-field-generated electron traps in oxide grown from polycrystalline silicon
Authors: Lee Han-Sheng , Feng Chin-Hu
Published: February 2003

A thin oxide film thermally grown from polycrystalline silicon was studied under pulsed high electric fields. Since the oxide was grown on a bumpy surface, both oxide surfaces are not smooth. The field enhancement caused by the bumpy surfaces produces high local electric fields. Electron traps are found in the oxide, and the generation of these traps is experimentally correlated to these local high fields. Measured results show that under constant applied voltage, the higher the local electric fields in the oxide, the faster the decay in the measured oxide current.
Low-temperature crystallization of doped a-Si:H alloys
Authors: Hamasaki T. , Kurata H. , Hirose M. , Osaka Y.
Published: February 2003

Crystallization of phosphorus-doped a-Si:H has been initiated at a substrate temperature below 200 °C, under the deposition conditions of a low flow rate of silane and in the presence of an external magnetic field. Along with the crystallization, the doping efficiency of the resulting Si:H films has been remarkably improved. Room-temperature conductivity as high as 27 Ω−1 cm−1 has been achieved at a doping ratio of NPH3/NSiH4=5.6×10−3 for a specimen deposited at 30 C. Optical emission spectroscopy during the plasma deposition has revealed that a weak emission intensity of the SiH band with respect to hydrogen lines and the absence of emission from the doubly excited states of hydrogen molecules are necessary conditions for the crystallization of doped Si:H films.
Themoelectric power and conductivity of As-doped a-Si:H:F
Authors: Nielsen Paul , Dalal V. L.
Published: February 2003

Thermoelectric power and conductivity measurements on As-doped a-Si:H:F have been combined with exact computations of conductivity and thermopower to determine the midgap density of states (1016 eV−1 cm−3) and maximum mobility (11 cm2 V−1 sec−1). The mobility edge is found to lie significantly deeper in the gap than in a-Si:H.
Efficient HgBr (B→X) laser oscillation in electron-beam-controlled-discharge-excited Xe/HgBr2 mixtures
Authors: Brown Robert T. , Nighan William L.
Published: February 2003

This letter reports the results of an investigation of HgBr(B2𝒥+→X2𝒥+) laser oscillation at 502 nm in Xe-HgBr2 mixtures excited using an electron-beam-controlled discharge. Measured values of instantaneous electrical-optical energy conversion efficiency were 2%, a level substantially higher than that typical of N2-HgBr2 mixtures. Calculations show that efficiencies of 5–10% may be possible under optimized conditions.
Acoustic wave properties and device characterization of 55°-rotated y-cut quartz
Authors: Josse F. , Vetelino J. F.
Published: February 2003

The properties of the acoustic wave propagation on or near the surface on the 55°-rotated y-cut in quartz are experimentally studied to determine the suitability of this cut in device applications. The wave is shown to be a combination of a surface-skimming bulk wave (SSBW) and a Bleustein-Guylaev wave. The velocity, temperature coefficient of delay, and attenuation associated with the wave have been measured. The measured attenuation was found to be significantly lower than previously investigated pure SSBW orientations. Using this wave, various bandpass filters were designed, fabricated, and tested. An aluminum layer deposited between the input and output electrodes was found to lower the insertion loss. The results are described and compared to the more commonly used SSBW orientations in quartz.
Room-temperature photoluminescence in spray-pyrolyzed CdS
Authors: Feldman Bernard J. , Duisman Jack A.
Published: February 2003

Very intense room-temperature photoluminescence has been observed near 1000 nm in CdS films prepared by spray pyrolysis. Since this material can be easily fabricated into p-n devices, this suggests the possibility of inexpensive electro-optical devices. Also, the photoluminescence spectra of CdS and amorphous Si:H are very similar.
lithium doping of polycrystalline silicon
Authors: Miller G. L. , Orr W. A.
Published: February 2003

Electrolytic lithium doping of high-purity polycrystalline silicon samples has been shown to increase not only the material conductivity but also the minority-carrier lifetime.
A boundary-layer treatment for turbulent detonation waves
Authors: Johnson Joseph A.
Published: February 2003

The profile of turbulent intensity versus Reynolds number from bursts found in an ignition front agrees with the Orr-Sommerfeld solutions for unstable boundary-layer flow. This result provides the first evidence of a formal connection between bursting transition to turbulence in flows which share the boundary-layer approximation but which are otherwise unrelated.
Three-prism loss measurements of optical waveguides
Authors: Won Y. H. , Jaussaud P. C. , Chartier G. H.
Published: February 2003

A new nondestructive method for measuring losses of an optical waveguide is presented. It uses three prisms, which enables the results to be independent of coupling efficiencies in and out of the guide. It requires only small strains on the guide and may be useful for fragile materials.
First results of material charging in the space environment
Authors: Mizera P. F. , Koons H. C. , Schnauss E. R. , Croley D. R. , Kan H. K. Alan , Leung M. S. , Stevens N. John , Berkopec F. , Staskus J. , Lehn William L. , Nanewicz J. E.
Published: February 2003

A satellite experiment, designed to measure potential charging of typical thermal-control materials at near-geosynchronous altitude, was flown as part of the SCATHA program. Direct observations of charging of typical satellite materials in a natural charging event (⩾ 5 keV) are presented. The results show some features which differ significantly from previous laboratory simulations of the environment.
Ionic species in a silane plasma
Authors: Haller Ivan
Published: February 2003

The abundances Aj of groups of higher silane ions SijH+k were measured mass spectrometrically in an rf glow discharge in SiH4 under conditions used for preparation of hydrogenated amorphous silicon. The ratio Aj/Aj−1 is about 0.3 nearly independently of j, of pressure, of degree of ionization, and of rf power. The mean hydrogen to silicon ratio for j⩾3 is 1.5±0.1 and pressure independent in the 0.017–0.100-Torr range. A mechanism postulating charge or hydride ion transfer and the addition of SiH4 as the most rapid reactions of silane ions is consistent with the observations.
Studies of steam-oxidized WSi2 by Auger sputter profiling
Authors: Rouse J. , Mohammadi F. , Helms C. R. , Saraswat K. C.
Published: February 2003

We have studied steam-oxidized WSi2 films sputter deposited upon Si and SiO2 substrates using Auger sputter profiling. As previously reported, steam oxidation produces an SiO2 surface layer. Silicon is supplied to the growing SiO2 layer by the conversion of the WSi2 to W5Si3, and additional Si is supplied by diffusion through the WSi2 layer only for the case of a Si substrate. The W5Si3 is distributed throughout the silicide layer, but with slightly higher concentration at the SiO2-silicide interface. This interface also contains an oxidized tungsten phase possibily is the form of a WxSiyOz compound.
Anodic etching of p-type silicon as a method for discriminating electrically active and inactive defects
Authors: Föll H.
Published: February 2003

Anodic etching of defects in p-type Si can be achieved at small applied voltages with dilute HF as electrolyte. The etching behavior of defects is strongly voltage dependent. At very small voltages only electrically active defects are etched; this is shown by comparison to EBIC. At higher voltages all defects are etched. The method provides a unique tool for investigating geometrical, structural, and electronic properties of defects in a simple way and offers considerable advantages over conventional techniques.
1.33-μm HgCdTe/CdTe photodiodes
Authors: Chu M. , Shin S. H. , Law H. D. , Cheung D. T.
Published: February 2003

Hg1−xCdxTe epilayers with a wavelength of ∼1.33 μm have been successfully grown by liquid phase epitaxy. Photodiodes were fabricated and measured. Analysis of the heterojunctions indicates that at room temperature the junction current at forward bias is dominated by a generation-recombination mechanism. The generation-recombination effective lifetime was estimated to be 2×10−7 s. A leakage current density of 9×10−6 A/cm−2 was observed at a reverse bias of 30 V, and the diode breakdown voltage was 70 V.
Cd2SnO4, CdIn2O4, and Cd2GeO4 as anodes for the photoelectrolysis of water
Authors: Koffyberg F. P. , Benko F. A.
Published: February 2003

From their photoelectrolysis spectra we have determined the lowest band gaps of Cd2SnO4, CdIn2O4, and Cd2GeO4 to be 2.12 (indirect), 2.23 (forbidden), and 3.15 eV (indirect), respectively; their flat-band potentials are +0.18, +0.25, and −0.82 V (SCE), respectively. This combination of band gaps and flat-band potentials, and the observed long-term instability of Cd2SnO4, makes these materials unsuitable as electrodes in solar photoelectrolysis cells.
Electrical behavior of polyvinylchloride thin films
Authors: Bahri R. , Singh H. P.
Published: February 2003

While investigating the metal–polyvinylchloride (<1500 Å)–metal sandwich structure using Al, Ag, Cu, and In electrodes, two kinds of switching properties were found. The symmetric sandwiches with aluminum electrodes exhibited voltage-controlled negative resistance (VCNR) with memory, while asymmetric structures displayed current-controlled negative resistance (CCNR) with memory. It was not possible to observe both kinds of switching phenomena in a single sample. The VCNR mechanism may be explained on the basis of high-field domains (or an accumulation layer) and the CCNR phenomenon may be explained on the basis of a filamentary model.
Plasma separation of InGaAsP/InP light-emitting diodes
Authors: Burton Randolph H. , Temkin H. , Keramidas V. G.
Published: February 2003

The application of plasma etching to the separation of InP/InGaAsP light-emitting diodes (LED’s) is reported. Device wafers (75 μm thick) were separated by fast (0.6 μm/min) anisotropic (2:1) etching in a CCl4/O2 plasma at 300 °C. The LED’s showed significant improvements in their reverse leakage currents over similar devices separated by conventional mechanical means. We find the separation-induced mechanical damage to be significant for conventional techniques causing both performance and yield loss. In contrast, the etched surfaces were free of mechanical damage resulting in a 100% yield of separated devices.
Determination of the free energy level of deep centers, with application to GaAs
Authors: Pons D.
Published: February 2003

A method is presented which allows the determination of the free energy level of deep centers by transient capacitance techniques. Preliminary results concerning deep centers in GaAs (E3, EL2, and chromium) are given.
Increased charge capacity in breakdown-limited metal-insulated semiconductor Hg1−xCdxTe devices using a ramped gate voltage
Authors: Chapman R. A. , Beck J. D. , Kinch M. A.
Published: February 2003

The useful charge capacity of a metal-insulated semiconductor (MIS) device can be increased by utilizing a ramped-gate-voltage mode of operation. The ramping technique is demonstrated on 4.5 and 9.4-μm long-wavelength cutoff HgCdTe MIS devices measured at 80 K with a 300-K background through ≃20° field of view and ?25% quantum efficiency. The gate voltage is ramped to increase the MIS well capacity at a rate slightly faster than the rate of photogenerated charge buildup in the inversion layer. The 4.5-μm device achieved a storage capacity of greater than 3.7×10−7 C/cm2 (≳45 ms storage time), while the 9.4-μm device achieved a storage capacity of 1.7×10−7 C/cm2 (300 μs integration time). The respective storage capacities demonstrated for these two wavelength bands are 3.5 and 17 times larger than obtained by the conventional pulsed-gate technique.
GaInAsP/InP stripe lasers with etched mirrors fabricated by a wet chemical etch
Authors: Miller B. I. , Iga K.
Published: February 2003

Monolithically etched-facet-mirror GaInAsP/InP stripe lasers (1.3 μm) were made using a wet chemical etching technique. Lasers with 20 μm stripes have current thresholds of 300 mA (room temperature, pulsed) about 50% higher than comparable cleaved-mirror lasers. Nearly single-mode operation up to 1.51th has been achieved with a cavity length of ∼180 μm.
Effect of growth terraces on threshold current density of (GaAl)As double-heterostructure laser
Authors: Shima K. , Segi K. , Imai H. , Fujiwara T. , Takusagawa M.
Published: February 2003

The variation of threshold current density Jth caused by the optical scattering loss due to growth terraces is experimentally and theoretically examined. It is found that Jth of the lasers in which growth terraces are parallel to the cavity direction is about 20% smaller than that of the lasers in which growth terraces are perpendicular to the cavity direction when the active-layer thickness d is 0.1 μm. The optical scattering loss due to growth terraces was estimated to be 50 cm−1 at d=0.1 μm when the cavity contains 10–15 terraces whose height and length are about 100 Å and 1μm, respectively.
Observations of gain and laser oscillation in the blue-green during direct pumping of XeF by microsecond electron beam pulses
Authors: Campbell J. D. , Fisher C. H. , Center R. E.
Published: February 2003

Laser oscillation on the C-A transition of XeF has been observed during direct excitation of Ar/Xe/F2 and Kr/Xe/F2 mixtures by microsecond electron beam pulses. The measured output energy was of the order of 1 mJ, and the laser performance was limited by the small magnitude of the net gain. Measured net gains in Ar/Xe/F2 and Ne/Xe/NF3 mixtures were ≲5×10−4 cm−1 . Fluorescence and laser spectra of Ar/Xe/F2 mixtures exhibited numerous absorption features. The laser emission intensity was maximum at ∼485 nm with an approximate 12-nm (FWHM) bandwidth. Substitution of Kr for Ar diluent dramatically improved laser performance.
High-efficiency flip-chip coupling between single-mode fibers and LiNbO3 channel waveguides
Authors: Bulmer C. H. , Sheem S. K. , Moeller R. P. , Burns W. K.
Published: February 2003

Coupling efficiencies of ≳70% have been consistently measured between single-mode fibers and LiNbO3 channel waveguides for TE and TM polarizations, using a Si V-groove/flip-chip arrangement. Tapered fibers in deep transverse grooves provide precise altitudinal alignment of the coupling fibers. These efficiencies are as high as those measured with a micropositioner and compare well with theoretical estimates of maximum coupling limited only by mode field distribution mismatch. Fiber/channel/fiber throughput losses of ∼3 dB and a polarization-independent interferometric waveguide modulator with fiber input and output are reported.
Picosecond optoelectronic detection, sampling, and correlation measurements in amorphous semiconductors
Authors: Auston D. H. , Johnson A. M. , Smith P. R. , Bean J. C.
Published: February 2003

The rapid relaxation of the photoresponse of high-defect-density amorphous semiconductors such as evaporated a-Si has been utilized to develop an electronic measurement capability which can generate and sample electronic transients with speeds ≲10 ps.
Effective elastic parameters of random composites
Authors: Devaney A. J. , Levine H.
Published: February 2003

Expressions for the effective bulk and shear moduli of a random distribution of elastic spheres embedded in an elastic matrix are derived using a self-consistent formulation of multiple-scattering theory. The expressions derived are found to agree with those obtained by previous workers in the weak-scattering limit but differ markedly from these earlier results when multiple-scattering effects are important. The influence of these multiple-scattering effects on the effective elastic constants is discussed and certain features thought to be caused by these effects are qualitatively studied.
Effect of accelerated growth rate (1–5 μm/h) on molecular beam epitaxial GaAs using Si as a dopant
Authors: Chai Young G.
Published: February 2003

The slow growth rate of molecular beam epitaxy (MBE) allows close to monolayer control of the film thickness. However, if the growth rate can be increased without significant loss of material quality or control, MBE may also become an economical way to grow epitaxial layers for optoelectronic and microwave devices. In this work, Si was studied as an n-type dopant at various growth rates. Hall mobilities of 60 036 cm2/V sec at 77 K and 8839 cm2/V sec at room temperature were achieved using a 1-μm/h growth rate. Higher mobilities were obtained at higher growth rates. Photoluminescence spectra of Si-doped films were dominated by near-band-edge emission. The growth rate of MBE GaAs can be increased at least up to 5 μ/h without change in electrical and optical characteristics of films.
Laser irradiation of nickel single crystals
Authors: Buene L. , Poate J. M. , Jacobson D. C. , Draper C. W. , Hirvonen J. K.
Published: February 2003

The effect of Q-switched Nd:YAG laser beam irradiation on virgin and ion-implanted Ni 〈110〉 single crystals has been studied. Rutherford backscattering and channeling have been used to establish crystal quality and to determine depth distributions and lattice locations of the implanted species (Au, Ag, and Ta) before and after laser treatment. Chanelling and Nomarski optical microscopy show that the Ni surface melts during the irradiation, followed by an epitaxial lattice regrowth resulting in (i) a formation of defects even in samples, (ii) a redistribution of the implanted atoms, and (iii) implanted atoms residing on substitutional lattice sites to form metastable solid solutions.
High-efficiency InP homojunction solar cells
Authors: Turner G. W. , Fan John C. C. , Hsieh J. J.
Published: February 2003

Conversion efficiencies up to 15% (AM1) have been obtained for antireflection-coated InP homojunction solar cells, the highest efficiency values reported for InP cells of any type. The cells were fabricated on n+ p p+ structures formed by liquid phase epitaxy on single-crystal InP substrates. The cell photovoltaic characteristics are not very sensitive to n+-layer thickness, indicating that the surface recombination velocity is not as high as in homojunction GaAs solar cells. The performance of various antireflection coatings has been investigated.
HgCdTe photodiodes formed by double-layer liquid phase epitaxial growth
Authors: Shin S. H. , Vanderwyck A. H. B. , Kim J. C. , Cheung D. T.
Published: February 2003

High-performance HgCdTe photodiodes have been formed by successive growth of p- and n-type epitaxial layers on CdTe substrates via the liquid phase epitaxy technique. These diodes exhibit high resistance-area (R0 A) products at high temperatures: R0 A products of 1 and 30 Ω cm2 have been observed at 283 and 200 K, respectively, for Hg0.68Cd0.32Te (λco=4.0 μm at 200 K). The saturation current density for the grown junction photodiode at 300 K is 0.12 A/cm2.
Highly oriented zinc oxide films grown by the oxidation of diethylzinc
Authors: Ghandhi Sorab K. , Field Robert J. , Shealy James R.
Published: February 2003

Zinc oxide films, with a high degree of c-axis orientation, have been grown on glass substrates by a chemical vapor deposition process involving the oxidation of diethylzinc. Film growth was carried out over the 200–500 °C temperature range; however, the maximum crystal orientation was found to occur with substrate temperatures between 325 and 400 °C. The effect of different substrate materials on crystallographic orientation is also described in this letter.
Observation of surface evaporation of Hg from HgTe crystals by means of energetic oxygen ion backscattering
Authors: Takita K. , Masuda K. , Kudo H. , Seki S.
Published: February 2003

Dissociation of Hg from the near-surface region of HgTe crystals was observed, up to 10 μm, by means of 42-MeV O5+ backscattering. Samples were annealed in vacuum at various temperatures up to 280 °C. The change of the backscattering spectra with annealing time and temperature indicated that the Hg atoms evaporated almost completely from the near-surface region to a depth d(t,T) and that only Te atoms remained there. The interface between the Te region and the HgTe crystal migrated at a velocity u(T) which was determined as u(T)=1.2×105 exp(−1.2 eV/kT) cm/sec. This is accounted for by a simple phenomenological model which suggests that the migration of the Hg atoms across the interface is the rate controlling process for the whole boundary migration process.
Laser noise in fiber-optic interferometer systems
Authors: Dandridge A. , Tveten A. B. , Miles R. O. , Giallorenzi T. G.
Published: February 2003

The amplitude stability of single-mode channeled-substrate planar diode lasers has been measured as a function of frequency (100 Hz–1 MHz) and driving current. The relative noise spectrum showed a decrease with increasing frequency and an overall reduction at all frequencies as the output power of the laser was increased. These results are compared with similar measurements of the most stable commercial single-mode HeNe lasers. The problems of laser amplitude noise in fiber-optic sensor systems is briefly discussed.
Studies of an unneutral electron cloud confined in a multiple-mirrored toroidal magnetic fielda)
Authors: Fisher A. , Gilad P. , Goldin F. , Rostoker N.
Published: February 2003

An unneutral electron cloud of 3×1013 electrons with a number density of 1011 cm−3 was compressed and confined by a multiple-mirrored toroidal magnetic field. The radial electric field associated with this electron cloud was about 105 V/cm. The electrons, having a large magnetic moment, were confined by the magnetic mirrors. An upper limit of 1 A was set on the induced current when a toroidal electric field of 10 V/cm was applied. This puts a limit n<4×108 cm−1 on the line density of electrons with perpendicular energy lower than 300 eV.
High-temperature contact structures for silicon semiconductor devices
Authors: Wittmer Marc
Published: February 2003

While thin films of TiN and TaN are good diffusion barriers in contact structures which use nickel or gold as a top layer, they show poor barrier properties if aluminum is used as a top layer. It is shown in this letter that stable high-temperature contacts on silicon semiconductor devices can be produced by using intermetallic compounds of aluminum in combination with TiN and TaN as barrier materials instead of pure aluminum.
Interaction of a pulsed XeF laser with an aluminum surface
Authors: Duzy C. , Woodroffe J. A. , Hsia J. C. , Ballantyne A.
Published: February 2003

The interaction of XeF laser radiation at 353 nm with an aluminum target in air at reduced (0.1 Torr) and ambient pressures has been studied. The thermal coupling at moderate fluxes (106–108 W/cm2) and long pulse length at 0.1 Torr was found to be ∼20%. Impulse coupling was also determined.
Shallow silicide contacts formed by using codeposited Pt2Si and Pt1.2Si films
Authors: Eizenberg M. , Föll H. , Tu K. N.
Published: February 2003

We have succeeded in making shallow silicide contacts on Si by using codeposited Pt2Si and Pt1.2Si alloyed films. Cross-sectional transmission electron microscopy showed that a uniform contact 10 nm deep was achieved by both films. Current-voltage measurements showed that the Schottky barrier height of these shallow contacts was as good as that of PtSi made by reacting pure Pt with n-Si.
Schottky barrier Ga1−xAlxAs1−ySby alloy avalanche photodetectors
Authors: Chin R. , Law H. D. , Nakano K. , Milano R. A.
Published: February 2003

Schottky barrier avalanche photodiodes have been fabricated in Ga1−xAlxAs1−ySby. The devices are planar and have semitransparent Au barriers. In addition, these detectors exhibit uniform photoresponse and dark current densities of ∼2.7×10−3 A/cm3 at the voltages where avalanche gains of 2 to 4 have been measured. This is the first report of avalanche gain in such a structure in the Ga1−xAlxAs1−ySby alloy system.
Improvement of GaAs-GaAlAs double-heterostructure laser wafer by Ga1−xAlxAs buffer layer
Authors: Shima K. , Morimoto M. , Imai H. , Fujiwara T. , Takusagawa M.
Published: February 2003

The optically induced degradation in GaAs-GaAlAs double-heterostructure (DH) laser wafers is examined at elevated temperatures. The degradation of the photoluminescence properties by optical pumping is considered to originate at the interface between an n-GaAlAs clad layer and a p-GaAs active layer, as it is greatly reduced by the insertion of a thin Ga1−xAlxAs buffer layer (x∼0.05, ∼0.05 μm thick) between these two layers. The degradation rate during optical pumping is correlated to laser life. The lasers fabricated from the DH wafers with the Ga1−xAlxAs buffer layer are still operating after 2000 h at 70 °C, whereas lasers without the buffer layer are inoperative after a few hundred hours.
Thermal diffusivity measurements using a pulsed dual-beam thermal lens technique
Authors: Gupta Mool C. , Hong Su-Don , Gupta Amitava , Moacanin Jovan
Published: February 2003

A novel pulsed dual-beam thermal lens technique for the determination of thermal diffusivity of liquids and solids was developed. In this technique a transient thermal lens is formed in the test specimen by using a dye laser pulse as a heating source and the thermal lens decay is monitored by means of a cw He-Ne laser. The technique is fast and contactless and avoids some of the major difficulties of conventional methods. Thermal diffusivities for water and a polycarbonate plastic were measured and found to be in agreement with literature values. Considerable simplification and minimization of certain errors was achieved by use of a reference material.
Visual observations of macroscopic inhomogeneous broadening of the R1 line in ruby
Authors: Jessop P. E. , Szabo A.
Published: February 2003

Observation of sharp spatial variations of the R1 fluorescence of ruby at 5 K resonantly excited by a 1-MHz-linewidth scanning cw dye laser indicates the presence of gross macroscopic strain broadening in Czochralski and Verneuil crystals. The implications of these results in several current studies are discussed.
A new intrinsic gettering technique using microdefects in Czochralski silicon crystal: A new double preannealing technique
Authors: Nagasawa K. , Matsushita Y. , Kishino S.
Published: February 2003

A new intrinsic gettering technique using microdefects in Czochralski-grown silicon wafers is proposed where a new double preannealing technique is applied to the wafer before the conventional silicon process. In the first step, high temperature (∼1000 °C), nonoxygen ambient annealing is carried out in order to diffuse dissolved oxygen from near the wafer surface. In the second step, extremely low-temperature (∼650 °C) annealing is added to introduce a high density of microdefects in the inner part of the wafer. This produces a wafer having both a nearly perfect denuded zone near the surface and a gettering site region in its bulk, regardless of the original quality of the wafer. This technique has proved to be effective in eliminating ion-implanation oxidation-induced stacking faults.
High rate deposition of thick piezoelectric ZnO films using a new magnetron sputtering technique
Authors: Hata Tomonobu , Noda Etsuji , Morimoto Osamu , Hada Toshio
Published: February 2003

ZnO films were prepared on glass substrates with a new reactive magnetron sputtering technique using a zinc target. A solenoid coil around a bell jar was used to cause an increase in the parallel component of the leakage lines to the target surface. Highly oriented ZnO films (c-axis orientation) were fabricated on the glass substrates. The deposition rate increases with increasing discharge current, and it attains 15 μm/h for (O2 50%:Ar50%), 11 μm/h for (81.5%:18.5%), and 9 μm/h for 100% oxygen. These films were obtained at a 500-mA discharge current and a 0.2-Torr total gas pressure. Resistivities of the films were 106–109 Ω cm. A piezoelectric coupling constant of thick ZnO films (∼30 μm) was obtained by measuring a frequency response of transducer impedance near the fundamental resonance frequency of the interdigital electrode. Experimental results were about 80% of the theoretical values.
Silane dissociation mechanisms and thin film formation in a low pressure multipole dc discharge
Authors: Drevillon B. , Huc J. , Lloret A. , Perrin J. , de Rosny G. , Schmitt J. P. M.
Published: February 2003

A silane plasma is generated by a hot cathode dc discharge in a partially confining multipolar magnetic structure yielding hydrogenated amorphous silicon thin films on the walls. The low-pressure range (0.1–5 mTorr) allows the analysis of the elementary processes for SiH4 dissociation. At low silane partial pressure the deposition rate remains in the range of 1–10 Å/sec, but the contribution of ions to deposition can reach up to 80% in contrast with standard glow discharges.
Optically pumped NSF molecular laser
Authors: Fischer T. A. , Tiee J. J. , Wittig C.
Published: February 2003

An optically pumped NSF laser, with tunable output in the region 618–658 cm−1, and pumped with a tunable transversely excited atmosphere (TEA) CO2 laser, is described. This laser promises to be an attractive source for laser isotope separation.
Hall mobility for electrons in undoped a-Si:H
Authors: Dresner J.
Published: February 2003

The Hall mobility μH of electrons in undoped a-Si:H has been measured between 200 and 550 K under illumination and in the dark. There are two distinct regimes: below Tt =360 K is independent of temperature, with a value μH ∼0.1 cm2 V−1 sec−1; above Tt, μH = 7.9 exp (−0.13 eV/kT) cm2 V−1 sec−1. The data can be fitted by a model where there is one set of conducting states for electrons and two possible modes of transport. Above Tt conduction is by thermally activated hopping; below Tt it takes place either by tunneling or by a temperature-independent jumping process. Conduction does not take place through extended states in the temperature range 200 – 550 K.
Anomalous low-frequency grain-boundary capacitance in silicon
Authors: Seager C. H. , Pike G. E.
Published: February 2003

The admittance of silicon bicrystals has been measured as a function of temperature, frequency, and dc voltage. In some cases the low-frequency capacitance is anomalously large. The ac response of a simple double depletion layer structure is calculated. The anomalous capacitive currents are due to an out-of-phase modulation of the barrier height caused by charge injected into grain-boundary traps.
Electrical power extraction from standing shock waves
Authors: Pearson J. B. , Kwan J. , Ahlborn B. A.
Published: February 2003

We have generated potentials of typically 1 V and extracted currents of several hundred millilamps from standing shock waves generated by imbedding wedge-shaped obstacles in supersonic flow.
Niobium nanobridge dc SQUID
Authors: Voss Richard F. , Laibowitz Robert B. , Broers Alec N.
Published: February 2003

For the first time high-resolution electron beam contamination lithography has been used to produce active sensing devices. dc SQUID’s (Superconducting quantum interference devices) with linewidths as small as 30 nm have demonstrated a minimum intrinsic energy resolution of 3h. This is the best value for any SQUID to date and approaches the limit ≈ h set by the uncertainty principle. The dependence of voltage noise on SQUID parameters is in agreement with a new small-signal model of SQUID noise.
Magnetostriction and magnetization of iron-based amorphous alloys
Authors: Ito Shigeyasu , Aso Koichi , Makino Yoshimi , Uedaira Satoru
Published: February 2003

The magnetostriction constant and saturation magnetization at room temperature are measured for iron-based amorphous alloys containing various kinds of metalloid and metal atoms, except Co and Ni. The data show that the magnetostriction constant is proportional to the square of the saturation magnetization for these alloys.
Electron quenching of KrF* and ArF*
Authors: Trainor Daniel W. , Jacob J. H.
Published: February 2003

The collisional deactivation by electrons of the upper laser levels of KrF* and ArF* has been measured. The rare-gas/fluorine binary mixtures were excited by a beam of fast electrons. These electron beam pulses were long enough to allow the use of a steady-state analysis of the fluorescence. Quenching rate constants near 2×10−7 cm3/sec have been obtained.
Fission-fragment nuclear lasing of Ar(He)-Xe
Authors: De Young R. J. , Shiu Y. J. , Williams M. D.
Published: February 2003

Nuclear-pumped lasing of Ar-Xe and He-Xe has been demonstrated using 235UF6 fission-fragment excitation. Fission fragments were created by absorption of thermal neutrons in a combination of gaseous 235UF6 and laser-tube wall coatings formed from UF6 chemical reaction products. At a pressure of 600 Torr Ar–(3%) Xe, lasing occurred at 2.65 μm in Xe. Up to 3 Torr of gaseous 235UF6 was added to 600 Torr Ar-Xe before serious laser quenching occurred. With 3 Torr of 235UF6 added, 38% of the energy deposition came from gaseous UF6 and the remainder from the uranium wall coating. The neutron flux at lasing threshold was found to be 4×1015 n/cm2 sec.
Light-induced radiative recombination centers in hydrogenated amorphous silicon
Authors: Pankove J. I. , Berkeyheiser J. E.
Published: February 2003

Laser irradiation of hydrogenated amorphous silicon produces recombination centers which shorten the lifetime of carriers. Some of the light-induced centers are radiative. The generation of the new radiative recombination centers increases with increasing temperature. All the light-induced centers disappear upon thermal anneal at about 210 °C.
Thermally stimulated depolarization of polyethylene between 5 and 190 K
Authors: Ronarc’h D.
Published: February 2003

The thermally stimulated depolarization spectrum of low-density polyethylene has been recorded in the temperature range 5–190 K. The γ relaxation of this polymer appeared to be composed of two principal processes. Using the thermal sampling technique, it was shown that the relaxation times in these processes were distributed in activation energy.
Reversible phase transformation in the Pd2Si-PdSi thin-film system
Authors: Tsaur B. Y. , Nicolet M-A.
Published: February 2003

The thermal stability of thin PdSi films has been studied at temperatures ranging between 300 and 700 °C. The PdSi, when in contact with crystalline Si, transforms into Pd2Si and Si at temperatures of 500–700 °C, a process contrary to the equilibrium-phase diagram. The rate of transformation was found to depend on the structure and orientation of the Si. Upon heating above 750 °C, Pd2Si transforms back to PdSi. However, PdSi is stable against annealing when in contact with Pd2Si or an inert substrate SiO2. We propose that the decomposition of PdSi into Pd2Si and Si in the presence of crystalline Si is due to a lower interface energy of the Pd2Si-Si interface compared to that of the PdSi-Si interface.
Work function of In2O3 film as determined from internal photoemission
Authors: Pan C. A. , Ma T. P.
Published: February 2003

The interface barrier heights of an In2O3-SiO2-Si structure have been studied in an internal pjotoemission experiment. A barrier height of 4.05 eV has been found for the In2O3(thermally evaporated)-SiO2 inrerface, Using the published electron affinity of SiO2, 0.95 eV, the work function of the thermally evaporated In2O3 film is determined to be 5.0 eV. This result is in excellent agreement with the value deduced from the C-V measurements performed on In2O3-Sio2-Si and Al-SiO2-Si metal-oxide-semiconductor (MOS) capacitors fabricated on the same wafer.
Zn-diffused back-illuminated p-i-n photodiodes in InGaAs/InP grown by molecular-beam epitaxy
Authors: Lee T. P. , Burrus C. A. , Cho A. Y. , Cheng K. Y. , Manchon D. D.
Published: February 2003

Epitaxial films of In0.53Ga0.47As lattice-matched to InP substrates have been grown by molecular beam epitaxy (MBE). The carrier concentrations were as low as 3×1015 cm−3. High-speed back-illuminated PIN photodiodes for use at 0.95–1.6 μm wavelength were made from the resulting layers.
Refractory-superconductor S-N-S microbridges
Authors: van Dover R. B. , de Lozanne A. , Howard R. E. , McLean W. L. , Beasley M. R.
Published: February 2003

We have successfully fabricated Nb-Au-Nb planar proximity-effect microbridges and increased our understanding of their behavior through the use of simple models. The magnitude and temperature dependence of the critical current are explained in terms of soft boundary conditions by combining Ginzburg-Landau analysis near Tc with the Likharev-Usadel approach at low temperatures. The low-voltage behavior near Tc is in good qualitative agreement with numerical calculations of the traditional TDGL model.
Relative responses of CsI and Au photocathodes to 70-psec, 500-eV x-ray pulses
Authors: Stradling G. L. , Medecki H. , Kauffman R. L. , Attwood D. T. , Henke B. L.
Published: February 2003

We present results of a laser Doppler-shift technique which gives the velocity profiles of ablatively accelerated targets. Measurements of the effects of laser beam nonuniformity on the target acceleration are presented and interpreted in the context of laser pellet fusion.
Electron velocity in Si and GaAs at very high electric fields
Authors: Smith P. M. , Inoue M. , Frey Jeffrey
Published: February 2003

A microwave time-of-flight technique was used to measure the drift velocity of electrons in thin Si and GaAs epitaxial layers at very high electric fields. The room-temperature velocity-field characteristic is reported for silicon at fields up to 130 kV/cm, and for GaAs at fields up to 215 kV/cm.