bluuebunny/crossref_metadata_2025 huggingface dataset:
cw argon laser annealing of ion-implanted silicon
Authors: Auston D. H. , Golovchenko J. A. , Smith P. R. , Surko C. M. , Venkatesan T. N. C.
Published: February 2003

We report on the annealing behavior of ion-implanted silicon exposed to cw argon laser radiation. The quality of the annealing was studied using channeling, in situ reflectivity, phase-contrast microscopy, and electrical resistivity. Strong dependence of anneal quality on laser power, crystal orientation, and implant dose is reported. Reflectivity measurements with a focused probing laser show that the onset of annealing occurs just below the melting point, and the annealing extends into the region where a thin layer of liquid silicon is formed at the crystal surface. We conclude that the physical mechanism responsible for crystal recovery is similar to the solid-state epitaxial regrowth observed for over-annealed samples.
Plasma return current discharge
Authors: Mangano J. A. , Hsia J. , Jacob J. H. , Srivastava B. N.
Published: February 2003

A discharge technique based on the use of an electron-beam-induced plasma return current to produce and heat large-volume plasmas is described. The results of discharge studies using this technique in attachment-dominated mixtures are presented. The results are found to be adequately described by a simple theory. The electron attachment rate by F2 inferred from these measurements agrees well with those of other workers. KrF laser action at 248 nm is reported in return-current discharge-excited mixtures of F2/Kr/He.
Defect distribution near the surface of electron-irradiated silicon
Authors: Wang K. L. , Lee Y. H. , Corbett J. W.
Published: February 2003

The surface-defect distributions of electron-irradiated n-type silicon has been investigated using a transient capacitance technique. Schottky, p-n junction, and MOS structures were used in profiling the defect distributions. Surface depletions of defects observed were attributed to the vacancy distribution but not that of oxygen and other capture center’s distribution. The vacancy diffusion length at 300 °K was estimated to be about 3–6 μm.
Integrated multijunction GaAs photodetector with high output voltage
Authors: Ilegems M. , Schwartz B. , Koszi L. A. , Miller R. C.
Published: February 2003

Integrated structures consisting of two P-I-N double heterostructure GaAs photodetectors, series connected by means of a tunnel junction, have been fabricated by molecular beam epitaxy. Open-circuit output voltages, external power efficiencies, and fill factors were 1.777 V, 33.4%, and 0.83, respectively, for antireflection-coated cells excited by ∼5 mW optical power from a focused DH AlGaAs laser emitting at λ=0.815 μm.
A 15% efficient silicon MIS solar cell
Authors: Godfrey R. B. , Green M. A.
Published: February 2003

Substantial improvements in energy conversion efficiency are reported for silicon MIS solar cells fabricated on both single-crystalline and semicrystalline substrates. Based on active area, AM1 efficiencies of 15.1% and 12.6%, respectively, have been obtained for 3.1-cm2 cells at 26 °C.
Fabrication and characterization of indium tin oxide (ITO)/polycrystalline silicon solar cells
Authors: Cheek G. , Inoue N. , Goodnick S. , Genis A. , Wilmsen C. , DuBow J. B.
Published: February 2003

Efficient indium tin oxide (ITO)/polycrystalline silicon heterojunction solar cells have been fabricated utilizing neutralized ion-beam sputtering techniques. These cells were fabricated on single-pass float-zone-refined silicon. Conversion efficiencies of 6.25% under AM1 illumination have been observed. Cells were analyzed by I-V characteristics and a scanning laser photoresponse technique. Qualitative minority-carrier lifetime has been mapped using the EBIC mode of a SEM. This has revealed a reduced photoresponse at the grain boundaries independent of grain size, and also at defect clusters within individual grains. Surface blemishes and etch pits are not important in reducing the cell photoresponse. It appears that the low-temperature processing inherent in semiconductor-insulator-semiconductor solar cells is applicable to polycrystalline material.
Atomic calcium laser: Pumped via collision-induced absorption
Authors: Trainor Daniel W. , Mani Siva A.
Published: February 2003

Lasing action was observed on the 3d4p 1F30→4s3d 1D2 and 4p2 1D2→4s4p 1P10 atomic transitions in calcium at 535 and 586 nm, respectively, when mixtures of atomic calcium and an inert gas were irradiated by a focused KrF laser (249 nm). No lasing was observed when the inert-gas collision partner was absent. The upper laser levels in these systems are not optically connected to the 1S0 ground state and thereby may be accessed via transitions in the inert-gas/calcium quasimolecule by absorption of KrF laser light in the wings of the 4s2 1S0 to 4s6p 1P10 calcium 2398.56-Å resonance transition (collision-induced absorption). The pump laser was a modified Tachisto using unstable cavity optics which provided focused intensities of nearly 1 GW/cm2. The calcium was produced in a stainless-steel heat pipe oven at temperatures near 1200 °K. Buffer gases studied include He, Ar, and Kr.
Band gap versus composition and demonstration of Vegard’s law for In1−xGaxAsyP1−y lattice matched to InP
Authors: Nahory R. E. , Pollack M. A. , Johnston W. D. , Barns R. L.
Published: February 2003

Measurements of lattice parameters and compositions for In1−xGaxAsyP1−y lattice matched to InP demonstrate the validity of Vegard’s law for this quaternary. The measured compositional dependence of the band gap shows a bowing parameter smaller than predicted from the previously measured band gaps of the four constituent ternaries.
Proton-induced x-ray emission analysis of thick targets—A new approach
Authors: Rashiduzzaman Khan Md.
Published: February 2003

A new procedure is proposed for the analysis of thick-target x-ray yield data from a proton-induced x-ray emission technique.
Ionic recombination of Kr+ and Kr+2 with F− in dense buffer rare gases
Authors: Flannery M. R. , Yang T. P.
Published: February 2003

Rates, α, for the recombination of Kr+ and Kr+2 with F− in various buffer rare gases (He, Ne, Ar, Kr, Xe) at 300 K are calculated for a wide range of gas pressures. For pressures 1–5 atm, the population of KrF* via recombination is greatest for Ne and Ar as third bodies, yielding α∼3×10−6 cm3 sec−1, while for pressures ≳10 atm, He is to be preferred as a buffer gas.
Far-infrared ring laser
Authors: Heppner J. , Weiss C. O.
Published: February 2003

The amplitude noise of optically pumped cw FIR lasers is drastically reduced by using a FIR ring resonator instead of a linear resonator. Laser emission switches from the clockwise mode to the counterclockwise mode at the FIR line center, a feature permitting precise frequency stabilization of FIR lasers. With an auxiliary retroreflector for one of the modes, unidirectional output occurs across the whole laser tuning width.
Generation of picosecond pulses of variable duration at 10.6 μm
Authors: Jamison S. A. , Nurmikko A. V.
Published: February 2003

Ultrashort transients of variable duration have been generated at 10.6 μm by operating a fast optical switch with picosecond pulses from a mode-locked Nd : glass laser. The switch, which takes advantage of the large free-carrier contribution to the infrared optical susceptibility in Ge, has been used to generate megawattt picosecond pulses at 10.6 μm by synchronous operation of a TEA CO2 laser with the 1.06 μm source.
cw laser oscillation on transitions of Cu+ in He-Cu halide gas discharges
Authors: Piper J. A. , Neely D. F.
Published: February 2003

We report cw oscillation on five transitions of Cu+ in the near infrared in hollow-cathode He-CuI, He-CuBr, and He-CuCl gas discharges. Excitation of the upper laser levels is attributed to thermal-energy charge-transfer reactions between ground-state He ions and neutral Cu atoms following discharge dissociation of the Cu halide molecules to generate free copper in the volume. Operating temperatures are in the range 400–550 °C and threshold currents for oscillation compare favorably with the lowest yet reported for sputtering Cu+ lasers.
A regenerative power amplifier operating on the blue-green line of the nitrogen ion laser
Authors: Collins C. B. , Carroll J. M. , Taylor K. N. , Lee F. W.
Published: February 2003

Operation of the nitrogen ion laser as an optical regenerative amplifier driven by a master oscillator allows the output to be effectively switched into the blue-green region of the spectrum. In this work an amplifier containing a dilute plasma of nitrogen ions was pumped by thermolecular charge transfer from He2+ produced by an intense e-beam propagating through several atmospheres pressure of gas mixture. The injection of relatively broadband output from a dye laser oscillator caused the output from the amplifier to switch entirely into the (0,2) vibrational component of the B→X electronic transition of N+2 at 470.9 nm. An output linewidth of 0.007 nm was achieved together with the early saturation of the laser transition needed for the extraction of power from the amplifier at optimal efficiency.
Dissociative attachment of electrons to F2
Authors: Schneider B. I. , Brau C. A.
Published: February 2003

The rate of dissociative attachment of electrons to F2 in mixtures with N2 and Ar has been measured over the electron mean energy range 0.9–4 eV. The results show that the rate is about 7×10−9 cm3/s at a mean energy of 1 eV, and decreases with increasing electron mean energy as (mean energy)−3/2.
’’Surface exchange’’ doping of MBE GaAs from S and Se ’’captive sources’’
Authors: Wood C. E. C.
Published: February 2003

Lead was not detectably incorporated in GaAs during MBE growth above 480 °C, and films grown under massive fluxes of lead show no degradation of material properties. This effect was utilized in the ’’surface exchange’’ n-type doping of GaAs with S and Se using PbS and PbSe as captive sources. The processes were shown to be efficient and able to produce relatively uncompensated material. 150-Å-wide spikes in doping could be easily produced, indicating a very low surface rate limitation to incorporation.
A semiempirical stopping-power formula for use in microprobe analysis
Authors: Shimizu Ryuichi , Everhart T. E.
Published: February 2003

A semiempirical method of determining the stopping power of valence electrons in metals and compounds is proposed, so that direct Monte Carlo calculations which take into account individual inelastic electron-electron collisions can be performed. The method is appliled to aluminum and poly(methylmethacrylate) as examples.
Electro-optic multimode waveguide switch
Authors: Campbell J. C. , Li Tingye
Published: February 2003

A new and simple electro-optic multimode waveguide modulator/switch that utilizes the concept of imaging in a multimode waveguide is described. Switching of a few low-order modes is obtained electro-optically by nonuniform modulation of the refractive-index profile of the active waveguide. The device can be realized in various sizes and configurations, thus enabling easy and efficient coupling to lasers, fibers, and other components. Extinction ratios of 13–20 dB with 20–80-V drive have been observed in several Ti-diffused LiNbO3 devices fabricated to date.
Transient reflectivity behavior of pure aluminum at 10.6 μm
Authors: Walters C. T. , Clauer A. H.
Published: February 2003

Time-resolved measurements of specular reflectivity of polished pure aluminum surfaces subjected to intense 10.6-μm pulsed-laser radiation in vacuum are reported. A sharp decrease in reflectivity to an anomalously low value (35%) was observed midway in the pulse followed by nearly complete recovery of full reflectivity near the end of the pulse. The peak-power-density threshold for this phenomenon was found to agree with the intrinsic surface melt threshold as determined from numerical heat-transfer calculations and microscopic examination of the samples.
A purely chemical HBr laser
Authors: Arnold S. J. , Foster K. D.
Published: February 2003

Purely chemical laser action in HBr has been achieved. Chlorine atoms which had been produced by the reaction of NO with ClO2 were reacted with molecular bromine to form bromine atoms which, in turn, reacted with HI to form vibrationally excited HBr. Multiline HBr output power of 0.58 W was obtained with lasing occurring on three lines from the v=1→0 vibrational band, P1−0(4), P1−0(5), and P1−0(6).
A high-efficiency GaAlAs double-heterostructure photovoltaic detector
Authors: Miller R. C. , Schwartz B. , Koszi L. A. , Wagner W. R.
Published: February 2003

An antireflection-coated GaAlAs double-heterostructure photovoltaic detector is described whose extrinsic power conversion efficiency is 56% when used with a focused 8075-μm wavelength laser beam. This, to our knowledge, is the highest photovoltaic efficiency yet reported. A partially reflective rear contact provides extrinsic quantum efficiencies exceeding 0.90 with a relatively thin active region. By restricting the diameter of this contact to 50 μm and using high dopings to reduce series resistance, open-circuit voltages of 1.15 V and fill factors up to 0.84 are obtained. The series resistance was 3.0 Ω, with 1.0 Ω being attributable to the contacts.
Water dielectric Blumlein-driven fast-electric-discharge KrF laser
Authors: Levatter Jeffrey I. , Bradford R. S.
Published: February 2003

A low-impedance water dielectric Blumlein pulse forming network (PFN) with an integral multi-arc-channel initiation switch has been developed as a fast-discharge laser pulser. Preionization of the laser medium is obtained by the use of behind-the-cathode uv arcs driven by an integral low-inductance water capacitor used in conjunction with the main PFN. With KrF, the laser has developed 180 mJ per pulse using a PFN impedance of 1.3 Ω at a laser efficiency of 1.2% from a 70-cm3 extracted volume. In preliminary experiments with a 0.6-Ω PFN, 250 mJ was obtained under similar conditions. The resulting discharge in both cases was extremely homogeneous due to the uniform preionization.
Characterization of electron and ion current flow in very large aspect-ratio terawatt diodes employing heated and unheated anodes
Authors: Genuario R. D. , Bailey V. L.
Published: February 2003

Electron-beam-focusing experiments using tapered hollow cathodes have been performed at power levels exceeding 1012 W and with diode aspect ratios (radius/anode-cathode spacing) of 24 and 45 (uncorrected for plasma motion). The spatial distributions of both the electron (using collimated p-i-n diodes) and ion currents (using quartz pressure gauges and Faraday cups) were measured simultaneously. Efficient electron-beam pinches were produced at large R/d (≈24) using a diode configuration that employed a small-diameter cathode and heated anode.
Linear polarization in birefringent single-mode fibers
Authors: Stolen R. H. , Ramaswamy V. , Kaiser P. , Pleibel W.
Published: February 2003

Single-mode fibers which maintain linear polarization are described. The fibers are birefringent and linear polarization is maintained along either of the two principal axes. The birefringence arises from the deliberate enhancement of anisotropic strains.
Tunable blue picosecond pulses from a flashlamp-pumped dye laser
Authors: Mialocq J. C. , Goujon P.
Published: February 2003

A flashlamp-pumped coumarin dye laser mode locked passively with a saturable absorber 3,3′-dihexyloxacarbocyanine iodide (DOCI) has produced tunable picosecond pulses shorter than 10 ps in the blue region of the spectrum between 475 and 490 nm. A single pulse switched from the train was used for fluorescence lifetime measurements. The excited-state lifetime τ of DOCI in pure ethyleneglycol was 505±10 ps.
Anisotropic melting and epitaxial regrowth of laser-irradiated silicon
Authors: von Allmen M. , Lüthy W. , Affolter K.
Published: February 2003

Using Nd-YAG laser pulses in the 100-μs regime, melting and regrowth of monocrystalline silicon is studied. It is shown that surface melting proceeds preferentially along the crystallographic axes. This leads to a characteristic surface pattern if uniform irradiation slightly above melting threshold is applied. Regrowth under these circumstances is epitaxial.
Single grain junction studies of ZnO varistors—Theory and experiment
Authors: Mahan G. D. , Levinson L. M. , Philipp H. R.
Published: February 2003

Single grain-grain junction measurements of the current-voltage characteristic of ZnO ceramic varistors are interpreted in terms of electron transmission through depletion layer barriers at the ZnO grain interface. The highly nonlinear varistor conduction process is associated with an abrupt thinning of the ZnO depletion layer due to valence-band hole injection when the bottom of the ZnO conduction band in the grain interior drops below the top of the valence band at the grain surface.
Mechanism of the SIMS matrix effect
Authors: Deline V. R. , Katz William , Evans C. A. , Williams Peter
Published: February 2003

Quantization of ion microprobe mass spectrometric analyses has been complicated by the variation in the ion yield of an element contained in different matrices. This work demonstrates that, for O− and Cs+ bombardment, these ion-yield variations are solely attributable to variations in the matrix sputtering yield. It is argued that the matrix sputtering yield determines the near-surface concentration of the ion-yield-enhancing species O and Cs.
An experimental display structure based on reversible electrodeposition
Authors: Camlibel I. , Singh S. , Stocker H. J. , VanUitert L. G. , Zydzik G. J.
Published: February 2003

Films of halide complexes of silver can be electrodeposited onto, or removed from, transparent indium tin oxide contacts in less than 10 msec using a clear liquid mixture of dimethyl sulfoxide (DMSO), silver halide, alkali metal halide, and bromine or iodine. The solutions do not attack the contacts, even at high voltages, as long as adequate silver remains in solution. Variations include a mulled mixture of an opacifier and superionic conductor particles in a variety of organic solvents. The electro-optic properties of experimental display structures are discussed.
The force of adhesion between solid surfaces in contact
Authors: Pollock H. M. , Maugis D. , Barquins M.
Published: February 2003

When two elastic solids of known interfacial and surface energies are placed in contact, various types of force are involved. It is shown that both the adhesive force and the peripheral attractive force are equal to one-half the difference between the apparent Hertz load and the applied load. A simple formula enables values of these forces to be derived.
Performance of a new high-intensity silicon solar cell
Authors: Frank Robert I. , Kaplow Roy
Published: February 2003

A new silicon solar cell, designed to have improved electrical, optical, and thermal transfer characteristics at very high incident light intensities, has been fabricated and provides experimental verification of the basic design concepts. The AM1 efficiency for nonoptimized cells is 12.8% at 25 °C. At 300 suns the efficiency increases to 19%. It is shown that efficiencies of over 25% are possible for this type of cell in a more-optimized form at intensities of ∼500–1000 suns.
Dynamics of laser-induced formation of palladium silicide
Authors: von Allmen M. , Wittmer M.
Published: February 2003

The formation of palladium silicide by laser irradiation of a thin Pd film evaporated on single-crystal silicon has been studied. We used 18-ns pulses from a Q-switched Nd : YAG laser to induce the reaction. The process of laser-induced silicide formation takes place through interdiffusion of the molten elements, followed by thermal quenching. A diffusion constant of 4×10−4 cm2/s was estimated. The reacted layer was found to consist of a mixture of different metal-silicon compounds.
Defect states associated with dislocations in silicon
Authors: Kimerling L. C. , Patel J. R.
Published: February 2003

The introduction and annealing of defect states in silicon stressed at 770 °C in compression have been studied by capacitance transient spectroscopy on Schottky-barrier structures. High-resistivity n-type samples are converted to p type. Low resistivity n-type samples are compensated but recover upon annealing. A large variety of defect states are observed with prominent features at E (0.68) after deformation. The spectra simplify upon annealing at 900 °C to two dominant states, E (0.38) and H (0.35).
Low-temperature field ionization of localized impurity levels in semiconductors
Authors: Banavar Jayanth R. , Coon Darryl D. , Derkits Gustav E.
Published: February 2003

The dynamics of field ionization from localized impurity levels in a semiconductor at low temperatures in an externally applied electric field are studied. The theory predicts a pronounced peak, characteristic of the impurities present and their state of ionization in the I-V curves of devices containing a uniform lightly doped region sandwiched between surface electrodes, provided that the applied voltage is swept sufficiently rapidly. The results of the theory are found to be in good agreement with experiments using silicon pin diodes.
Thermocurrent spectra of γ-phase-containing PVF2 films
Authors: Abkowitz M. , Prest W. M. , Luca D. J. , Pfister G.
Published: February 2003

A comparison of ac and dc thermocurrents in γ-phase-containing PVF2 films prepared by different techniques isolates spectral features unique to γ-phase crystallites. The spectral changes that result from the in situ thermal conversion of γ- and α-phase-containing films provides a self-consistent verification of assignments.
Instantaneous two-dimensional concentration measurements in a jet flow by Mie scattering
Authors: Long Marshall B. , Webber Bruce F. , Chang Richard K.
Published: February 2003

The instantaneous (9 μsec) two-dimensional concentration in a turbulent jet has been measured by imaging the Mie-scattered light from a seeded flow onto a low-light-level TV camera and processing the data in a computer. The average concentration and rms concentration fluctation profile, as well as the spatial concentration fluctuation correlations, have been obtained.
Experiments on optically pumped three-level dimer lasers
Authors: Wellegehausen B. , Heitmann H. H.
Published: February 2003

Stable unidirectional ring laser oscillation of optically pumped dimer molecules is reported. In the case of Na2, single-frequency output powers up to 200 mW tunable over a range of 4 GHz were obtained. By means of oscillator amplifier systems the forward-backward amplification profiles and the level splitting due to the dynamic Stark effect were measured.
Explanation for low-efficiency Cu2O Schottky-barrier solar cells
Authors: Olsen L. C. , Bohara R. C. , Urie M. W.
Published: February 2003

Surface analyses combined with barrier-height studies indicate that Cu2O Schottky barriers made with low-work-function metals (Yb, Mg, and Mn) are essentially Cu/Cu2O cells due to reduction of the Cu2O surface and subsequent interdiffusion phenomena. The copper-rich region essentially determines the barrier height. As a result, efficiencies of Cu2O Schottky-barrier solar cells are usually less than 1%. It is concluded that to achieve significant increases in Cu2O cell efficiencies, MIS or heterojunction device structures must be utilized.
Electron-microscope observation of structure domains in the ferroelastic phase of lead phosphate, Pb3(PO4)2
Authors: Ayroles R. , Torres J. , Aubree J. , Roucau C. , Tanaka M.
Published: February 2003

We have used for the first time the electron-microscopy technique to reveal the pure ferroelastic phase domain structure of lead phosphate, Pb3(PO4)2. The domain configuration confirms previous identifications of the symmetry elements lost at the transition. The domains are found separated by thin walls whose thicknesses are less than 50 Å. This and other recent studies suggest narrower walls in ferroelectrics and in ferroelectric ferroelastics than were envisaged from earlier theoretical models. The very high values reported by different authors are believed to be due to the resolution limitations of the experimental setup used. Fruitful consequences are expected from a thorough understanding of the stresses and lattice distortions associated with the ferroelastic domain structure.
The role of the C state in the XeF laser
Authors: Finn T. G. , Palumbo L. J. , Champagne L. F.
Published: February 2003

Ne/Xe/NF3 mixtures were irradiated by a cold-cathode e-beam, and the fluorescence yields of the B and C states of XeF were measured as a function of neon pressure from 200 to 5300 Torr. At low neon pressures, the fluorescence yield of the B state corresponds to one photon emitted for each neon ion formed. As the neon pressure is increased the fluorescence yield of the B state decreases, but the ratio of the C emission to B emission approaches unity. If the C is formed through a channel which is independent of the B state, then the ultimate efficiency of the XeF laser is severely limited. However, analysis of the data with a XeF kinetics model indicates that the enhanced C emission results from two-body quenching of the B state by neon. We conclude that the XeF laser performance has been limited by other processes, namely, incomplete vibrational relaxation and ground-state bottlenecking.
Laser irradiation of silicon containing misfit dislocations
Authors: Hofker W. K. , Oosthoek D. P. , Eggermont G. E. J. , Tamminga Y. , Stacy W. T.
Published: February 2003

Silicon containing misfit dislocations caused by ion implantation and thermal annealing were irradiated with a scanning Q-switched Nd-YAG laser. It was found that misfit dislocations can be removed completely. It was established that this removal is thermally stable. Evidence for a melting-resolidification mechanism was observed. The thermally stable removal of misfit dislocations is discussed in terms of this mechanism.
Diffusion of Cd acceptors in InP and a diffusion theory for III-V semiconductors
Authors: Tien P. K. , Miller B. I.
Published: February 2003

In the interest of developing InP technology for optoelectronic devices, we report a method of diffusing Cd into InP using CdP2 and P as the source. The method provides an acceptor concentration p=1018–1019 cm−3, a diffusion depth controllable by the amount of P used in the source, and a steep diffusion front suitable to the formation of abrupt p-n junctions. We have also analyzed kinetics of diffusion and present a theory which explains the anomalous behavior of diffusion profiles observed in the experiments.
Electronic defect levels in self-implanted cw laser-annealed silicon
Authors: Johnson N. M. , Gold R. B. , Gibbons J. F.
Published: February 2003

Electronic defect levels in self-implanted cw Ar-laser-annealed silicon have been measured by deep-level transient spectroscopy. The electron emission spectrum is dominated by two levels near the middle of the silicon forbidden energy band with activation energies of ∼0.49 and 0.56 eV. These levels can be spatially resolved in the depletion layer of Schottky diodes due to a more rapid decrease with distance in the density of the shallower level. In samples receiving a 450 °C furnace anneal (after laser irradiation) an additional level appears at 0.28 eV; the defect density is shown to decrease monotonically with depth into the silicon substrate.
Cross-shaped proximity-effect bridge
Authors: Kobayashi Tadayuki , Nakajima Koji , Yamashita Tsutomu , Onodera Yutaka
Published: February 2003

A superconducting bridge, based on the proximity effect, consisting of four superconductors coupled together through a weakly superconducting cross-shaped region is fabricated in a Nb/Ta thin film by means of photolithographic and anodization techniques. The experimental results of the bridge are interpreted in a simple equivalent circuit model.
The mechanism of optically induced degradation in InP/In1−xGaxAsyP1−y heterostructures
Authors: Mahajan S. , Johnston W. D. , Pollack M. A. , Nahory R. E.
Published: February 2003

Optically degraded regions in In1−xGaxAsyP1−y layers, grown on (001) InP substrates by liquid phase epitaxy, have been examined in detail by transmission electron microscopy. It is shown that these areas are associated with dislocation clusters or bundles which are aligned parallel to the 〈100〉 directions. We conclude that the observed features develop by nonradiative-recombination-enhanced glide of threading and inclusion-generated dislocations present in the layers.
Near-infrared noncritically phase-matched second-harmonic generation in KNbO3
Authors: Günter P.
Published: February 2003

Noncritical type-I phase matching at room temperature has been observed in KNbO3 for λpm=860 nm using the nonlinear optical coefficient d32=−40‖d11 (SiO2) ‖. By increasing the crystal temperature up to 180 °C the phase-matching wavelength is increased to λpm=950 nm. At room temperature the efficiency for second-harmonic generation was 15% for a power density Iω =0.5 MW/cm2 of the fundamental and for a crystal length l=5.74 mm.
Low-current-threshold strip-buried-heterostructure lasers with self-aligned current injection stripes
Authors: Tsang W. T. , Logan R. A. , van der Ziel J. P.
Published: February 2003

A modified strip-buried-heterostructure (SBH) laser is described where the LPE growth process self-aligns the current-confining stripes with the active GaAs strips. With these lasers current thresholds have been reduced from ∼180 mA in previous SBH laser to ∼70 mA for active GaAs strips of 380×10×0.2 μm. Excellent linearity in light-current characteristics and symmetry in laser output from both mirrors were obtained under both pulsed and cw operations. cw operation has been achieved at heat-sink temperature as high as 115 °C. The current thresholds Ith have an exponential variation with temperature of the form Ith∝exp(T/T0) where T0 was 110 °K. Relaxation oscillation and self-pulsation was not observed for lasers with clean transverse modes in pulsed response up to current injection levels as high as 4Ith.
The electronic structure of HgCl and HgBr
Authors: Wadt W. R.
Published: February 2003

A b initio configuration interaction calculations using effective core potentials are presented for the low-lying electronic states of HgCl and HgBr. The B→X laser wavelengths and vibrational constants for the B and X states are in very good agreement with experiment. The equilibrium separations (Re) for the B and X states in HgCl (HgBr) are found to be 2.42 (2.61 Å) and 2.93 Å (3.04 Å), respectively. The purely electronic radiative lifetime for the B state in HgCl (HgBr) is calculated to be 27.5 ns (27.6 ns). The mixing of ionic and covalent character in the X and B states and its effect on the R dependence of the transition moment is discussed briefly. Finally, the possibility of self-absorption is considered.
Measurements of refractive-index dispersion by optical waveguiding
Authors: Tanaka Keiji
Published: February 2003

A technique for measuring the refractive-index dispersion in light-guiding thin films by means of the prism-coupling method is reported. A collimated polychromatic light beam is employed, and the wavelength dependence of synchronous angles is determined spectroscopically. A representative experiment performed on an amorphous specimen reveals its usefulness for investigating the detailed dispersion characteristics of thin films with accuracies better than 0.001.
Optical properties of ultrathin PbO layers grown on Pb films
Authors: Harris E. P. , Hauge P. S. , Kircher C. J.
Published: February 2003

The optical properties of ultrathin (2–7 nm) oxide layers grown on Pb films have been measured by spectroscopic ellipsometry over the 1.4–5.4-eV photon energy range. The shape of the dielectric function resembles published measurements made on much thicker evaporated layers of orthorhombic PbO, but with the absorption edge shifted downward in energy by about 0.6 eV. The band gap in our case is estimated to be 2.8 eV from the theory of direct allowed transitions.
Direct observation of the vacancy structure of depleted zones in tungsten ion irradiated at 10 K
Authors: Wei Ching-Yeu , Seidman David N.
Published: February 2003

The structure of depleted zones (DZ’s) created by the in situ irradiation of tungsten specimens, at 10 K, with 30-keV W+, Mo+, or Cr+ ions has been studied by field-ion microscopy. As the mass of the 30-keV ion was decreased the following observations were made: (1) the spatial extent of the DZ’s increased; (2) the vacancy concentration within the DZ’s decreased; (3) the fraction of isolated monovacancies increased; and (4) subcascades formed within the DZ’s.
Effect of nitrogen-ion implantation on the unlubricated sliding wear of steel
Authors: Lo Russo S. , Mazzoldi P. , Scotoni I. , Tosello C. , Tosto S.
Published: February 2003

The effect of 30-keV nitrogen-ion implantation on the unlubricated sliding wear of type-38 NCD4 steel has been investigated. The effect of implants is seen to reduce the amount of wear for nitrogen doses above 1017 ions/cm2. The reduction in the wear persists also after removal of a material thickness greater than the penetration depth of the implanted nitrogen ions.
LaF3 insulators for MIS structures
Authors: Sher A. , Miller W. E. , Tsuo Y. H. , Moriarty John A. , Crouch R. K. , Seiber B. A.
Published: February 2003

Thin films of Laf3 deposited on Si or GaAs substrates have been observed to form blocking contacts with very high capacitances. This results in comparatively-hysteresis-free and sharp C-V (capacitance-voltage) characteristics for MIS structures. Such structures have been used to study the interface states of GaAs with increased resolution and to construct improved photocapacitive infrared detectors.
Direct observation of voltage barriers in ZnO varistors
Authors: Krivanek O. L. , Williams P. , Lin Yi-Ching
Published: February 2003

Voltage barriers in a ZnO varistor have been imaged by voltage-contrast scanning electron microscopy. They are due to grain boundaries and are capable of supporting voltage differences of up to about 4 V.
Brillouin backscatter dependence upon pulse amplitudes, timing, target material, and geometry
Authors: Ripin B. H. , McLean E.A.
Published: February 2003

The dependence of stimulated Brillouin backscatter upon pulse amplitudes, timing, target material, and geometry from a prepulse-formed plasma is found. The applicability of these results to backscatter from a structured continuous pulse is discussed.
Unidentified acceptors in silicon and germanium
Authors: Ohmer M. C. , Lang J. E.
Published: February 2003

An empirical rule for calculating the ionization energy and the infrared absorption spectra of five unidentified acceptor levels in silicon and germanium is presented. The success of this rule may imply that these levels result from interactions between unlike substitutional group-III impurities.
Polarization-sensitive coherent anti-Stokes Raman spectroscopy
Authors: Oudar Jean-Louis , Smith Robert W. , Shen Y. R.
Published: February 2003

We show that by using polarization coherent anti-Stokes Raman spectroscopy, the detection sensitivity of weak Raman modes is greatly enhanced. The spectra of the real part, the imaginary part, and the absolute magnitude of the resonant nonlinear susceptibility can be separately measured. Raman modes with cross sections as low as 2×10−4 times that of the 992-cm−1 mode of benzene are detectable with less than 10-kW-peak-power lasers.
Dynamics of Q-switched laser annealing
Authors: Auston D. H. , Golovchenko J. A. , Simons A. L. , Surko C. M. , Venkatesan T. N. C.
Published: February 2003

Using time-resolved optical-reflectivity measurements, the duration of the thin liquid layer accompanying Q-switched laser annealing in Si, Ge, and GaAs has been determined. The duration of this melted layer has been studied as a function of laser energy at 1.06- and 0.53-μm wavelength for both implanted and unimplanted samples. Thresholds for initiation of melting and damaging the surface are obtained directly. With the aid of channeling–Rutherford-backscattering measurements, the duration of melt necessary for annealing implanted samples is determined. Results for unimplanted silicon at 530 nm are compared with recent numerical calculations. In addition, measuremnts of the fall time of the reflectivity as the liquid-solid interface approaches the surface enables us to estimate regrowth velocities. A simple scheme is also discussed for efficient annealing with dual wavelengths.
Ion-implanted laser-annealed GaAs solar cells
Authors: Fan John C. C. , Chapman Ralph L. , Donnelly Joseph P. , Turner George W. , Bozler Carl O.
Published: February 2003

Conversion efficiencies up to 12% at AM1 have been obtained for ion-implanted laser-annealed (IILA) GaAs solar cells utilizing a shallow-homojunction n+/p/p+ structure without a GaAlAs window. The n+ layer was formed by Se+-ion implantation into the p layer, which was grown epitaxially by chemical vapor deposition on a single-crystal p+ substrate. The implanted layer was annealed, without encapsulation, by scanning with a cw Nd : YAG laser. Cell metallization was performed by electroplating, and an antireflection coating was formed by anodic oxidation of the n+ layer.
High-current-density relativistic electron beams in conical diodes
Authors: Gilad P. , Nardi E. , Zinamon Z.
Published: February 2003

Current densities of 20 MA/cm2 are obtained in the focus of a modest (450 kV, 60 kA) beam in a conical ’’parapotential’’ diode. The electron flow in the diode is studied using pinhole photography and bremsstrahlung angular distribution measurements.
High-field dark currents in thin CVD silicon nitride with graded interfacial composition
Authors: Andrews J. M. , Jackson B. G. , Polito W. J.
Published: February 2003

Ellipsometric measurements of thin CVD Si3N4 films deposited on Si reveal a graded composition of silicon oxynitride with increasing oxygen content as the Si-Si3N4 interface is approached. Measurements of steady-state dark currents, injected into Si3N4 from negatively biased Al contacts at constant average field, Eav=Vτ−1=6 MV/cm, have been fitted to an empirical relation, J=J0 exp(τ0/τ), where τ is the film thickness and τ0=1039 Å. Increased film conductivity with decreasing thickness τ is attributed to diminished electron trapping as τ approaches the centroid of trapped charge, δ∼100 Å.
High-density optical recording with (Ga,Al)As DH lasers
Authors: Asbeck P. M. , Cammack D. A. , Daniele J. J. , Lou D. , Heemskerk J. P. J. , Kleuters W. J. , Ophey W. H.
Published: February 2003

(Ga,Al)As lasers were employed to optically machine a series of 1-μm-diam holes in 200–300-Å-thick films of tellurium on polymethylmethacrylate substrates at repetition rates as high as 10 MHz. By modulating the hole repetition frequency, limited bandwidth video signals were successfully recorded. The hole machining was accomplished with lasers which operated in fundamental transverse and lateral mode at high pulsed power (typically greater than 150 mW), in conjunction with a high-collection-efficiency focusing system. The lasers were operated at low (⩽20%) duty cycle in order to minimize internal heating. The hole sizes obtained and the repetition rates achieved are appropriate for a high-density optical recording system.
A nickel-ion laser
Authors: Jain Kanti
Published: February 2003

Laser oscillation has been achieved in singly ionized nickel at 796.24 and 797.54 nm in a hollow-cathode discharge. This, to our knowledge, is the first report of inversion in Ni II.
Effect of pressure and pulse length on the isotopically selective photodissociation of freon CF2Cl2 under CO2 laser pulses
Authors: Neve de Mevergnies M.
Published: February 2003

When the 13C species of CF2Cl2 is excited by short TEA-CO2 laser pulses, the isotopic enrichment of the resultant photodissociation remains constant between 0.25 and 2 Torr CF2Cl2 pressure, whereas excitation of the 12C species yields a monotonous decrease of the enrichment with pressure in the same range. These results are compared to those obtained with longer pulses and with the 32S and 34S species of SF6.
High-efficiency AlGaAs/GaAs concentrator solar cells
Authors: Sahai R. , Edwall D. D. , Harris J. S.
Published: February 2003

Efficiencies of 25% have been obtained with 1-cm-diam AlGaAs/GaAs heteroface concentrator solar cells utilizing an ultrathin AlGaAs window layer design. A low specific resistance (<0.005 Ω cm2) Ohmic contact is achieved by direct contact to the p-GaAs active layer. Liquid phase epitaxy has been developed to grow <500-Å thick window layers on large-area (3.3×3.3 cm) GaAs substrates. Four 1-cm-diam cells are produced from each wafer and demonstrate the potential for larger-scale production.
Electrical conductivity of Ge films during laser-induced crystallization
Authors: Lovato M. , Wautelet M. , Laude L. D.
Published: February 2003

The electrical conductivity of Ge films is traced during and after pulsed medium power laser irradiation (≲1 kW/pulse, 10−6-sec pulse duration). A model is given which allows one to understand the physical processes involved in laser-induced crystallization, namely, the influence of the film-substrate interface on nucleation, crystal size, and crystal growth.
Silicon implantation in GaAs
Authors: Tandon J. L. , Nicolet M-A. , Eisen F. H.
Published: February 2003

The electrical properties of room-temperature Si implants in GaAs have been studied. The implantations were done at 300 keV with doses ranging from 1.7×1013 to 1.7×1015 cm−2. The implanted samples were annealed with silicon nitride encapsulants in H2 atmosphere for 30 min at temperatures ranging from 800 to 900°C to electrically activate the implanted ions. Results show that the implanted layers are n type, which implies that the Si ions preferentially go into Ga sites substitutionally. For low-dose implants, high (∼90%) electrical activation of the implanted ions is achieved and the depth distribution of the free-electron concentration in the implanted layer roughly follows a Gaussian. However, for high-dose implants, the activation is poor (<15% for a 900 °C anneal) and the electron concentration profile is flat and deeper than the expected range.
Real-time spectral analysis of far-infrared laser pulses using an SAW dispersive delay line
Authors: Fetterman H. R. , Tannenwald P. E. , Parker C. D. , Melngailis J. , Williamson R. C. , Woskoboinikow P. , Praddaude H. C. , Mulligan W. J.
Published: February 2003

Spectral analysis of high-power pulsed D2O lasers has been accomplished using SAW dispersive delay lines. Both the contributions of longitudinal modes and the tuning of the stimulated Raman line at 385 μm have been observed.
An elastic-wave ellipsometer for measurement of material property variations
Authors: Thompson R. B. , Vasile C. F.
Published: February 2003

Electromagnetic-acoustic transducers (EMAT’s) can excite and detect elastic shear waves with electronically controlled elliptical polarizations. These can be used to construct an ellipsometer for precise measurement of mechanical properties of solids, in analogy to devices presently used in optical studies. The elastic-wave case differs from the optical case in two important ways. Longitudinal as well as transverse waves will, in general, exist, and the propagation medium, as well as the surfaces, play an important role in determining the system response. A device is described which is designed to avoid the former mode conversion effects on thin plates. The results of two simple experiments to demonstrate its performance are then reported. In one, measurement of the texture of a metal plate demonstrates the ability to sense bulk property changes which alter the relative velocities of the two-wave components. In the second, measurements of the effect of a fluid on one side of the plate demonstrates the ability to sense surface changes which alter the relative attenuation of the two-wave components. The technique appears likely to find future application in the high-precision measurement of a number of elastic properties, particularly in view of the fact that it requires no couplant and hence can perform well under various adverse conditions.
Raman scattering from anodic oxide-GaAs interfaces
Authors: Schwartz G. P. , Schwartz B. , DiStefano D. , Gualtieri G. J. , Griffiths J. E.
Published: February 2003

The nature of the interface between anodically grown oxide films and gallium arsenide substrates was studied using Raman backscattering. Room-temperature spectra of GaAs covered with as-grown anodic films as well as anodized samples dried under nitrogen at 250°C showed only the first-order longitudinal (LO) and transverse (TO) optical modes and the less-intense two-phonon features of the GaAs substrate. Heating the films at 450°C and above results in the appearance of intense LO (257 cm−1) and TO (198 cm−1) bands due to crystalline arsenic and the structureless Raman scattering near 200–250 cm−1 due to amorphous arsenic. Polarized Raman spectra indicate that elemental arsenic is not an intrinsic oxidation product of the room-temperature anodization. We suggest that the thermally induced solid-state interfacial reaction, As2O3+2GaAs→Ga2O3+4As, is responsible for the presence of arsenic at the oxide-semiconductor interface following annealing.
Smooth multilayer films suitable for x-ray mirrors
Authors: Haelbich Rolf-Peter , Segmüller Armin , Spiller Eberhard
Published: February 2003

Multilayer coatings consisting of very smooth ReW and carbon films used as near-normal-incidence reflectors show theoretical performance in the 150–200-Å wavelength region and should allow the fabrication of useful normal-incidence mirrors for wavelengths as short as 50 Å.
Triode plasma etching
Authors: Minkiewicz V. J. , Chapman B. N.
Published: February 2003

Reactive-plasma etching is conventionally carried out using one power supply to both generate the glow discharge and to control the flux and energy of ion bombardment on the substrate. A three-electrode, or triode, configuration is described in which these two functions are controlled quasi-independently; results obtained with this arrangement are described. These results are somewhat similar to those obtained with a diode RIE system, except that control of the substrate voltage allows another degree of freedom over etch rates, etch selectivity, and wall profiles.
Continuous 300 °K laser operation of single-quantum-well AlxGa1−xAs-GaAs heterostructure diodes grown by metalorganic chemical vapor deposition
Authors: Dupuis R. D. , Dapkus P. D. , Chin R. , Holonyak N. , Kirchoefer S. W.
Published: February 2003

Stripe-geometry single-quantum-well AlxGa1−xAs-GaAs double-heterostructure laser diodes (Lz∼200 Å) grown by metalorganic chemical vapor deposition are shown to operate continuously at 300 °K on the first (n=1) electron–to–heavy–hole (e→hh) or first (n′=1′) electron–to–light–hole (e→lh) confined-particle transitions (h/ω−Eg∼11 meV). These laser diodes exhibit an external differential quantum efficiency as high as ηext∼80% (output power 5.4 mW at 65 mA drive current).
A new technique for the determination of isotopic species using Zeeman scanning of an atomic line
Authors: Koizumi Hideaki , Hadeishi Tetsuo , McLaughlin Ralph D.
Published: February 2003

We measured the vibrational-rotational line profiles of 14N 16O and 15N 16O in the electronic transition spectrum by using the magnetically scanned ion line of 114Cd(II) at 2165.017 Å. The observed separation between the line of 14N 16O, Q[10(1/2)] and the line of 15N 16O, Q2[11(1/2)] was 49.6 GHz, and the half-width of these lines was 4.4 GHz. We could observe the line profile of 15N 16O in naturally occurring NO, even though its abundance is 0.37%. Also, the ratio 15N/14N in nitric acid was determined with this technique. The lower detection limit was about 50 ppb.