bluuebunny/crossref_metadata_2025 huggingface dataset:
X-ray photoelectron spectroscopy studies of Ag photodoping in Se-Ge amorphous films
Authors: Zembutsu S.
Published: February 2003

The Ag-deposited Se80Ge20 (at. %) amorphous films are found to show a large chemical shift (∼1.2 eV) in the Se 3d level toward lower binding energies and to form a Ag2Se phase on the surface region. The chemical shift of the Se 3d level by Ag photodoping becomes large with increasing UV exposure (15 mW/cm2) and is saturated at about 0.6 eV for UV exposure of more than 60 s. The chemical shift can be almost explained by the electronegativity scale. Pauling’s charge on the Se atom can be estimated as −0.04 in the Ag-photodoped state.
Origin of the defects observed after laser annealing of implanted silicon
Authors: Mesli A. , Muller J. C. , Salles D. , Siffert P.
Published: February 2003

Deep-level transient spectroscopy experiments, performed on 31P+-implanted and laser-annealed silicon, have shown that the defect concentration is considerably reduced when a conventional thermal annealing is performed before the laser treatment. A model is presented which explains the origin of the defects.
Improved figure of merit in obliquely cut pyroelectric crystals
Authors: Shaulov Avner
Published: February 2003

In pyroelectric crystals with high dielectric anisotropy, a significantly higher figure of merit can be obtained using cuts at oblique angles to the pyroelectric axis, rather than the conventional cuts lying perpendicular to it. For a particular material an appropriate cut can be selected to provide the maximum figure of merit attainable at the chosen temperature of operation. Experimental data obtained in deuterated triglycine fluoroberylate crystals show that optimum oblique cuts can yield an increase as great as a factor of 3 in the figure of merit of this material.
Pseudogap state density in sputtered a-Si:H from field effect and capacitance measurements
Authors: Weisfield Richard , Viktorovitch Pierre , Anderson David A. , Paul William
Published: February 2003

Changes in film deposition procedure have permitted us to measure, for the first time, field-effect-induced current multiplication up to 104 in sputtered a-Si:H. The deduced Fermi-level state density of the order of 1×1017 eV−1 cm−3 agrees within small errors with analysis of capacitance measurements on codeposited samples.
Silicide formation in Pd-a-Si:H Schottky barriers
Authors: Thompson M. J. , Johnson N. M. , Nemanich R. J. , Tsai C. C.
Published: February 2003

This letter gives the first report of a direct correlation of Schottky barrier characteristics to silicide growth on a-Si:H. Changes in diode ideality factor (from 1.2 to 1.05) produced by annealing can now be directly attributed to growth of Pd2Si as demonstrated by Raman spectroscopy. Unannealed samples show long-term changes in characteristics at room temperature due to slow silicide growth. However, Pd Schottky barriers possess ideal stable characteristics once silicide growth is complete.
Scattering loss reduction in ZnO optical waveguides by laser annealing
Authors: Dutta Subhadra , Jackson Howard E. , Boyd J. T. , Hickernell Fred S. , Davis R. L.
Published: February 2003

We report successful laser annealing of ZnO optical waveguides deposited on an amorphous SiO2 layer thermally grown on Si. A significant improvement in the optical attenuation of the fundamental mode from several dB/cm before laser annealing to as low as 0.01 dB/cm after laser annealing is observed. Scattering loss measurements for the m = 1 and m = 2 mode are also reported. We attribute the reduction in loss primarily to an improvement in the quality of the ZnO film in the region near the ZnO-SiO2 interface.
Continuous-wave mirrorless lasing in optically pumped atomic Cs and Rb vapors
Authors: Sharma A. , Bhaskar N. D. , Lu Y. Q. , Happer W.
Published: February 2003

Continuous-wave lasing in optically pumped atomic cesium and rubidium vapor is observed without the use of any feedback mirrors. The stimulated emission in a number of infrared wavelengths is restricted to a very narrow angle in both the forward and backward directions.
a-SiC:H/a-Si:H heterojunction solar cell having more than 7.1% conversion efficiency
Authors: Tawada Y. , Okamoto H. , Hamakawa Y.
Published: February 2003

A clear valency electron controllability with substitutional impurity doping in the hydrogenated amorphous silicon carbide has been found. The amorphous silicon carbide is produced by the plasma decomposition of [SiH4(1−X)+CH4(X)] with the dopant gas of a B2H6 or PH3 system. Electrical and optical properties of doped amorphous SiC films are briefly demonstrated. Utilizing this a-SiC:H as a wide-band-gap window material, we have developed a new type of a-SiC:H/a-Si:H heterojunction solar cell. A typical cell performance is Voc = 0.887 V, Jsc = 12.33 mA/cm2, fill factor = 0.653, and the conversion efficiency of 7.14% under AM-1 illumination.
High-field transport of holes in silicon
Authors: Smith Phillip M. , Frey Jeffrey , Chatterjee P.
Published: February 2003

The room-temperature drift velocity of holes in silicon has been measured for electric fields ranging from 9 to 234 kV/cm using a microwave time-of-flight technique. The measured velocity saturates at a value of 0.96±0.05×107 cm/sec at a field strength of 175 kV/cm.
Effect of ion-beam sputter damage on Schottky barrier formation in silicon
Authors: Fonash Stephen J. , Ashok S. , Singh Ranbir
Published: February 2003

Abnormal rectifying behavior has been observed in molybdenum/silicon Schottky barrier diodes produced by ion-beam sputter deposition of Mo on single-crystal Si. Rectifying, rather than ohmic contacts are obtained on p-type Si, while ohmic behavior is seen on n-type Si. These results are contrary to the usual results reported in the literature, and are shown to be caused by ion-beam surface damage of Si. The damage does not simply cause a surface layer of high-recombination velocity, but rather tends to bend the Si band edges downwards, irrespective of the Si conductivity type.
Molecular beam epitaxial growth of single-crystal Fe films on GaAs
Authors: Prinz G. A. , Krebs J. J.
Published: February 2003

Molecular beam epitaxy methods have been used to grow good quality magnetic single-crystal films of bcc Fe on fcc GaAs substrates. These films were characterized by Auger, reflection high energy electron diffraction (RHEED) and ferromagnetic resonance (FMR) techniques. Both RHEED and FMR indicate that the best crystal quality occurs for substrate temperatures in the 175–225 °C range. For 200-Å films the Fe surface lattice constant agrees with that of bulk α-Fe.
Hydrogen elimination during the glow-discharge deposition of a-Si:H alloys
Authors: Kampas F. J. , Griffith R. W.
Published: February 2003

A model of the deposition of a-Si:H films by silane glow discharge is presented. Three steps are involved: SiH2 addition, H2 elimination, and cross linking. The model is based upon SiH2 gas-phase chemistry and explains the dependence of hydrogen content of a-Si:H upon substrate temperature.
678-mV open-circuit voltage silicon solar cells
Authors: Blakers A. W. , Green M. A.
Published: February 2003

A new high-performance cell structure has been developed, combining the better features of metal insulator semiconductor and p-n junction technologies. The metal-insulator-NP junction (MINP) cell technology described has an inherently superior performance to either of its constituent technologies, producing open-circuit voltages up to 678 mV (AMO, 25 °C) for silicon cells. Analysis of the dark saturation current of MINP devices as a function of bulk resistivity indicates that both bulk and surface recombination contribute to this current, with the former dominating. Prospects for exceeding 700-mV open-circuit voltage with this approach are discussed. The structure is particularly well suited for fabrication using ion implantation.
Radiative cooling with selectively emitting ethylene gas
Authors: Hjortsberg A. , Granqvist C. G.
Published: February 2003

We discuss passive cooling of ethylene gas which radiates predominantly in the wavelength range for which the atmospheric counter radiation is low for dry air. The radiative properties of the gas were investigated by spectrophotometry, and the parameters relevant for efficient cooling were computed. Daytime cooling to a temperature ∼10 °C below that of the ambient was demonstrated with a simple device.
Real-time tritium imaging
Authors: Malinowski M. E.
Published: February 2003

A real-time image of a tritium-containing titanium film has been made by detecting the secondary electrons produced by tritium β decay with a simple two-element electrostatic lens and microchannel plate image intensifier. The obtained image indicates that a resolution of better than 100 μm is currently obtainable and suggests that image magnification to enhance resolution should be possible.
New model of electron free path in multiple layers for Monte Carlo simulation
Authors: Horiguchi Seiji , Suzuki Masanori , Kobayashi Toshio , Yoshino Hideo , Sakakibara Yutaka
Published: February 2003

A new model of an electron free path in multiple layers is proposed for Monte Carlo simulation of electron trajectories. In this model, the free path is calculated taking into account not only the scattering probability in the layer involving the initial scattering point but also that in the layers along the scattering direction. The result, simulated with the new model, agrees with the experimental result much better than results obtained with conventional models for backscattered electron intensity. It is also suggested that the simulation accuracy for the electron beam lithography is improved using the new model.
Plasma annealing of ion implanted semiconductors
Authors: Ianno N. J. , Verdeyen J. T. , Chan S. S , Streetman B. G.
Published: February 2003

An electron beam generated by a gas discharge is used to anneal ion implanted silicon. The discharge operating parameters as well as the electron beam energy are measured. Finally, plasma annealing of BF+2 implanted n-type silicon is examined by observing the sheet resistivity of the implanted layers and the resulting diode characteristics.
Detection of 1.5-μm wavelength laser light emission by infrared-excitable phosphors
Authors: Mita Yoh
Published: February 2003

Laser emission from a 1.5-μm wavelength InGaAsP/InP diode was shown to be efficiently converted to visible or to near-infrared light by Er-containing infrared-excitable phosphors. The visible emission has been markedly enhanced in Yb-sensitized phosphors under 0.97-μm wavelength auxiliary light irradiation especially under weak 1.5-μm wavelength excitation. The enhancement mechanism has proved to be Yb-sensitized quantum counter action.
Measurement of the velocity distribution of sputtered Na atoms from NaCl by Doppler shift laser fluorescence
Authors: Yu Ming L. , Grischkowsky D. , Balant A. C.
Published: February 2003

The velocity distribution of sputtered Na atoms from NaCl during 15 keV, Ar+ bombardment was measured by a Doppler shift laser fluorescence technique. Contrary to other measurements, the sputtered Na atoms were found to have a velocity distribution identical to that of a three-dimensional Maxwell–Boltzmann gas.
Three-dimensional nonlinear theory of the free electron laser
Authors: Sprangle P. , Tang Cha-Mei
Published: February 2003

This letter presents a self-consistent nonlinear treatment of three-dimensional effects associated with the wiggler field, the electron beam, and the radiation beam in a steady-state free electron laser (FEL) amplifying configuration. Our formulation also incorporates various efficiency enhancement schemes. We find that the 3-D effects can lead to substantial differences in the results compared to the 1-D theory. Finally a 3-D numerical illustration of a 10.6-μm FEL is given.
Optical heterodyne saturation spectroscopy
Authors: Hall J. L. , Hollberg L. , Baer T. , Robinson H. G.
Published: February 2003

We discuss a refined, hybrid rf/optical technique for studying sub-Doppler saturated absorption/dispersion resonances with excellent precision and symmetry. Sensitivity is limited mainly by fundamental noise in the signal. Resonance profiles obtained in I2 are in remarkable agreement with theory. The method promises a new level of accuracy for laser locking to an optical resonance.
Substitutional solid solubility limits during solid phase epitaxy of ion implanted (100) silicon
Authors: Williams J. S. , Elliman R. G.
Published: February 2003

High resolution channeling techniques have been used to investigate the maximum nonequilibrium solid solubility which can be achieved during low-temperature (⩽600 °C) epitaxial regrowth of high-dose antimony and indium implanted (100) silicon. The substitutional impurity concentration is observed to increase with implant dose and saturate at a limiting concentration well above the maximum equilibrium solid solubility for antimony or indium in silicon. Observed correlations between the measured solubility limits, epitaxial regrowth rates, and intriguing impurity redistribution effects suggest that impurity size and attendant lattice strain at the crystal-amorphous interface may determine the substitutional solubility limit for low-temperature annealing, where impurity diffusion lengths are negligible during the time of epitaxial recrystallization.
New display based on electrically induced index-matching in an inhomogeneous medium
Authors: Craighead H. G. , Cheng Julian , Hackwood S.
Published: February 2003

The operation of a new light modulation device that employs electric field controlled light scattering in an inhomogeneous medium is described. The orientation of a nematic liquid crystal, contained in micrometer sized inclusions in a nonabsorbing solid, is changed to produce a varying refractive index. When the refractive index of the liquid crystal matches that of the solid, the composite medium is nonscattering and transparent. If the refractive indices do not match, the medium is scattering and opaque. High contrast ratios have been measured for transmitted light with a response time of a ∼1 ms. The application of this technique to passive display devices is discussed.
Imaging performance of a normal incidence soft x-ray telescope
Authors: Henry J. Patrick , Spiller Eberhard , Weisskopf Martin
Published: February 2003

We have made the first measurements of the imaging performance of a normal incidence soft x-ray telescope at BKα (0.183 keV, 67.6 Å). The performance is quite good; at 1.5° off axis the resolution is about 1 arcsec full width at half-maximum and 50% of the reflected power within 512 arcsec is contained within a diameter of 5 arcsec.
Electrowetting optical switch
Authors: Jackel J. L. , Hackwood S. , Beni G.
Published: February 2003

Continuous electrowetting (CEW) and refractive index matching have been used as the physical basis of an optical switch for multimode fibers. This switch has low cross talk (∼−30 dB), fast response times (∼20 ms), low operating voltage (∼1 V), and low power consumption (∼1 μW).
Deuterium passivation of grain-boundary dangling bonds in silicon thin films
Authors: Johnson N. M. , Biegelsen D. K. , Moyer M. D.
Published: February 2003

Hydrogen passivation of silicon grain boundaries has been investigated by using deuterium as a readily identifiable isotope which duplicates hydrogen chemistry. Deuterium detection with high sensitivity was achieved with secondary-ion mass spectrometry. Diffusion of deuterium in single- crystal silicon and polycrystalline silicon thin films at low temperatures (e.g., 350 °C) clearly demonstrates enhanced diffusion along grain boundaries. Defects at grain boundaries were detected by electron-spin resonance and identified as silicon-dangling bonds. Deuterium passivation of grain boundaries is revealed by correlated deuterium diffusion and dangling-bond annihilation in polycrystalline silicon films.
Multiline injection mode locking of a transversely excited atmosphere CO2 laser
Authors: Giles R. , Offenberger A. A.
Published: February 2003

A multiline injection mode locked transversely excited atmosphere CO2 laser has been operated for use in high intensity laser-plasma interaction experiments. Laser pulses of 390 MW and 2-ns duration with up to three equal power lines were produced by installing intracavity SF6 cells in both the injection and slave oscillators to tune them to the desired laser transition. A simple model defines the laser system requirements to achieve simultaneous oscillation on several lines.
Composition modulation in liquid phase epitaxial InxGa1−xAsyP1−y layers lattice matched to InP substrates
Authors: Henoc Pierre , Izrael Alice , Quillec Maurice , Launois Huguette
Published: February 2003

Liquid phase epitaxial layers of InxGa1−xAsyP1−y grown lattice matched to InP〈001〉 substrates, in the concentration range 0.53⩽x⩽0.88, have been studied by transmission electron microscopy. For the usual growth temperatures, solid instability was predicted for compositions in the range 0.55≲x≲0.75. Indeed a quasiperiodic variation of a strain contrast, though very light in some cases, is always observed in the 〈100〉 and 〈010〉 directions in that composition range, and never outside. The pseudoperiodicity is of the order of 1000 Å. Local concentration measurements have been performed on one sample using a scanning transmission electron microscope. They show that the strain contrast, quite strong in that sample, is related to a concentration modulation. The measured variations on x and y are as high as 0.1, and they keep the ratio x/y constant, which is consistent with phase separation observed on nucleated InxGa1−xAsyP1−y.
Non-mass-analyzed ion implantation from a solid phosphorus source
Authors: Spitzer M. B. , Bunker S. N.
Published: February 2003

A phosphorus ion beam, extracted from a Freeman ion source charged with elemental phosphorus, has been investigated for use in solar cell fabrication. Mass spectroscopy of the beam indicates the absence of both minority-carrier lifetime degrading impurities and hydrogen. The ion beam, without mass analysis, was used for ion implantation of solar cells, and performance for all cells was found to be equivalent to mass-analyzed controls.
Optical pulse chirp modification in degenerate four-wave mixing at finite pump powers
Authors: Shockley R. C.
Published: February 2003

Exact solutions of the linearized transient envelope equations for degenerate four-wave mixing in a finite-length cell show that reflection coefficients near unity severely restrict the conditions under which chirp reversal occurs, and can lead to nulls in the amplitude of the reflected and transmitted fields.
Dislocation breakaway in photoplastic CdS
Authors: Mayer Vivian F. , Galligan James M.
Published: February 2003

Dislocation breakaway has been observed in CdS during plastic deformation under illumination. The magnitude and frequency of such breakaways are found to be strongly temperature dependent in the range from 0 to 70 °C. This observation suggests a way to distinguish among several theories of photoplasticity.
Tunneling through a controllable vacuum gap
Authors: Binnig G. , Rohrer H. , Gerber Ch. , Weibel E.
Published: February 2003

We report on the first successful tunneling experiment with an externally and reproducibly adjustable vacuum gap. The observation of vacuum tunneling is established by the exponential dependence of the tunneling resistance on the width of the gap. The experimental setup allows for simultaneous investigation and treatment of the tunnel electrode surfaces.
Electron spin resonance of AsGa antisite defects in fast neutron-irradiated GaAs
Authors: Wörner R. , Kaufman U. , Schneider J.
Published: February 2003

Strong electron spin resonance spectra of the As4+Ga antisite defect have been observed in fast neutron-irradiated GaAs. Both in originally n-type and p-type materials the defect introduction is ≲3 cm−1. Thermal annealing of the AsGa defect occurs between 450 and 500 °C. This annealing stage is also characteristic for the recovering of electrical conductivity and infrared transparency of GaAs after particle irradiation and ion implantation. It is suggested that these phenomena are microscopically explained by thermal annihilation of antisite defects.
Triboluminescence of silica core optical fibers
Authors: Zink Jeffrey I. , Beese William , Schindler John W. , Smiel A. J.
Published: February 2003

The triboluminescence spectrum of optical fibers contains two prominent peaks, one at 430 nm and the other at 630 nm. The relative intensities vary with fiber type. The time dependence of the emission is related to the crack rate terminal velocity and to the creation and annihilation of moving cracks.
A high efficiency single-crystal CdSe photoelectrochemical solar cell and an associated loss mechanism
Authors: Frese Karl W.
Published: February 2003

The conversion efficiency of a n-CdSe (112̄0) photoelectrochemical solar cell was found to be 12.4% in alkaline K3Fe(CN)6/K4Fe(CN)6 electrolyte. The pH of the electrolyte is critical for observing high efficiency and stable photocurrent. A selenium corrosion layer acts as a light filter to block the photocurrent.
Laser enhanced etching in KOH
Authors: von Gutfeld R. J. , Hodgson R. T.
Published: February 2003

We have used a focused laser beam to perform localized etching on 〈111〉 Si and several ceramic materials submerged in an aqueous potassium hydroxide solution. The etching process is accompanied by localized melting of the material whenever high material removal rates are observed. Mil sized blind holes, through holes, and slots have been fabricated. Instantaneous etch rates as high as 200 μm/s have been observed in alumina/TiC ceramic for 1-W of incident laser power (∼106 W/cm2). An average rate of a 15 μm/s has been observed in the etching of through holes in 10-mil silicon with 15 W of incident laser power (∼107 W/cm2).
Longitudinal mode spectra of diode lasers
Authors: Streifer W. , Scifres D. R. , Burnham R. D.
Published: February 2003

A theory is presented which explains the longitudinal mode spectra of diode lasers. The theory is based on spontaneous emission coupling into the longitudinal modes and the excellent agreement with experimental data for both gain guided and real refractive index waveguide diode lasers is obtained because of the more accurate and detailed modeling of the spontaneous emission coupling and the laser itself.
Stress-enhanced carrier mobility in zone melting recrystallized polycrystalline Si films on SiO2-coated substrates
Authors: Tsaur B-Y. , Fan John C. C. , Geis M. W.
Published: February 2003

Thermal stress is found to have a significant influence on the carrier mobilities in Si films prepared by zone melting recrystallization of polycrystalline Si on SiO2-coated substrates. Films recrystallized on SiO2-coated fused quartz substrates exhibit a large tensile stress, which enhances the electron mobility by ∼75% compared to the stress-free Si films recrystallized on SiO2-coated Si substrates. In contrast, Si films recrystallized on SiO2-coated sapphire substrates are under a large compressive stress, which yields an increase of ∼10% in hole mobility compared to the stress-free films.
Strong orientation dependence of the formation of surface stacking faults during oxidation of float-zone silicon
Authors: Dieleman J. , Martens T. H. G.
Published: February 2003

The crystal orientation of float-zone silicon has a huge effect on the number of oxidation-induced stacking faults formed at the surface. Whereas 〈100〉 Si can be oxidized without formation of any stacking faults, the same oxidations introduce numerous stacking faults in 〈111〉 Si. These results are very different from those reported for Czochralski material.
Schottky contacts on chemically etched p- and n-type indium phosphide
Authors: Hökelek E. , Robinson G. Y.
Published: February 2003

The Schottky-barrier energy φB for Al, Ni, Co, Pd, Au, and Ag contacts on chemically etched 〈100〉 surfaces of both p- and n-type InP were measured and the metallurgical behavior of the contact structures were studied using Auger electron spectroscopy. φB was found to be a function of the chemical reactivity of the contact metal with the InP substrate. Extensive outdiffusion of In was observed in the Au and Ag contacts. The results indicate that the chemical effects at the metal-semiconductor interface are a determining factor in the formation of InP Schottky barriers.
Nanosecond infrared laser stimulation of luminescence in rare-earth doped sulfides
Authors: Gasiot J. , Bräunlich P. , Fillard J. P.
Published: February 2003

Optically stimulated luminescence (OSL) from CaS:Eu,Sm and SrS:Eu,Sm phosphors, previously exposed to ionizing radiation, is shown to occur with response and decay times of less than 50-ns full width at half-maximum. This result indicates that fast high-resolution OSL imaging of spatial dose distributions is possible via stimulation of the dose proportional luminescence with a tightly focused scanning laser beam. The two phosphors investigated are efficiently stimulated with the beam from a Nd:yttrium aluminum garnet (YAG) laser. The large dynamic dose range of these materials represents a distinct advantage of OSL imaging over conventional x-ray radiography. In addition, the laser scanning technique readily lends itself to image digitalization and processing. Real-time imaging appears feasible.
High quality transparent heat reflectors of reactively evaporated indium tin oxide
Authors: Hamberg I. , Hjortsberg A. , Granqvist C. G.
Published: February 2003

Transparent and heat reflecting indium tin oxide films were prepared by electron beam evaporation of In2O3+9 mol.% SnO2 onto glass in an oxygen atmosphere of ∼5×10−4 Torr. Visible light absorption less than 2%, thermal infrared reflectance exceeding 90%, and a dc resistivity of ∼3×10−4 Ω cm were obtained for 0.3-μm-thick films deposited on a substrate at 300 °C. Similar properties could be achieved with substrate temperatures as low as 150 °C. By antireflection coating the films with an MgF2 layer, the visible transmittance exceeded the transmittance of the uncoated glass while the infrared reflectance was practically unchanged.
Spheres of the metallic glass Au55Pb22.5Sb22.5 and their surface characteristics
Authors: Lee Mark C. , Kendall James M. , Johnson William L.
Published: February 2003

Spheres of the metallic glass Au55 Pb22.5 Sb22.5 have been formed up to a size of approximately 1.5 mm in diameter. X-ray diffraction was used to establish the glassy nature of the samples and to provide evidence of two phase-separated glass regions. Scanning electron microscopy provided a direct visual observation of the two-phase amorphous network on the surface of the sphere. The physical dimensions of the phase-separated regions were observed to be cooling-rate sensitive. Energy dispersive spectroscopy indicated that the compositions of these two glassy phases were Au-rich and Pb-rich, respectively, confirming the results of Kim and Johnson. In addition, the spheres exhibited an unusual surface smoothness of better than ±250 Å.
Confinement of laser-generated carriers in semiconductors by induced lattice temperature gradients
Authors: van Driel H. M. , Preston J. S. , Gallant M. I.
Published: February 2003

The generation of large carrier densities in semiconductors by pulsed laser excitation can be accompanied by a large lattice temperature gradient near the surface. We formulate the coupled transport equations which describe the evolution in space and time of the carrier density and the carrier/lattice temperature below the melting point. A large temperature gradient is seen to influence the diffusion of carriers through the thermoelectric effect (which enhances diffusion) and energy band-gap gradients (which in most materials counteract diffusion). For high laser intensities we conclude that the latter effect dominates, leading to a region of carrier confinement and enhanced lattice heating near the surface.
A proposal and numerical simulation of N+N
N+ Schottky device for ballistic and quasiballistic electron spectroscopy
Authors: Hesto P. , Pone J-F. , Castagne R.
Published: February 2003

A new structure is proposed for the spectroscopy of ballistic or quasiballistic electrons in GaAs submicronic N+NN+ device. A theoretical study based on a Monte Carlo simulation is presented in order to prepare an experimental study.
Acoustic emission triangulation of disturbances and quenches in a superconductor and a superconducting magnet
Authors: Tsukamoto O. , Iwasa Y.
Published: February 2003

Locations of disturbances and quenches in a superconductor and a superconducting magnet have been determined by using a multiple set of acoustic emission (AE) sensors. The letter presents an AE triangulation technique and experimental results.
61Ni Mössbauer measurements of nickel microprecipitates produced in LaNi5 by cyclic hydrogen absorption and desorption
Authors: Rummel H. , Cohen R. L. , Gu̇tlich P. , West K. W.
Published: February 2003

The hydrogen storage material LaNi5 has previously been shown to degrade into LaH2 and (presumably) Ni metal on repeated absorption and desorption of hydrogen. 61Ni Mössbauer measurements show directly the presence of nickel microprecipitates in severely degraded material.
Gas-puff Z pinches with D2 and D2-Ar mixtures
Authors: Bailey J. , Ettinger Y. , Fisher A. , Rostoker N.
Published: February 2003

Results obtained with the University of California, Irvine gas-puff Z-pinch experiment are described for deuterium and deuterium-argon mixtures. This experiment utilizes a hollow cylindrical gas puff injected between electrodes driven by a 4.8-kJ capacitor bank. Various gas compositions have been tested, including pure deuterium, 90% D2-10% Ar, and up to 10% D2-90% Ar. We have observed the stages of collapse and its rate, electron density at the pinch, neutron yield, and the time dependence of x-ray and neutron emission. When a 90% D2-10% Ar mixture is injected, the plasma annulus is observed to separate into two columns which implode concentrically.
Origin and elimination of defects in SiO2 thermally grown on Czochralski silicon substrate
Authors: Itsumi Manabu , Kiyosumi Fumio
Published: February 2003

Oxide defect density for Czochralski Si (CZ-Si) substrates is found to be nearly one order of magnitude larger than that for float-zone Si (FZ-Si) substrates. The oxide defect density for CZ-Si substrates, subjected to an additional sacrifice oxidation, followed by etchback of the resultant oxides, is found to agree with that for FZ-Si substrates subjected to no special treatment. The origin of the oxide defects for CZ-Si is inferred to be metallic impurities originating from the substrates.
Electrical excitation of an XeCl laser using magnetic pulse compression
Authors: Smilanski I. , Byron S. R. , Burkes T. R.
Published: February 2003

Excitation of a small repetitively pulsed XeCl laser by a magnetic pulse compressor (MPC) is reported. The MPC makes use of a saturable inductor constructed out of relatively low frequency ferrites. It compresses a 300-ns pulse into a 50-ns pulse, enabling a low di/dt, long life thyratron to drive a fast discharge laser. The laser has operated at 750 Hz for several hours with an average optical output power of 3.5 W.
X-ray rocking curve study of Si-implanted GaAs, Si, and Ge
Authors: Speriosu V. S. , Paine B. M. , Nicolet M-A. , Glass H. L.
Published: February 2003

Crystalline properties of Si-implanted 〈100〉 GaAs, Si, and Ge have been studied by Bragg case double-crystal x-ray diffraction. Sharp qualitative and quantitative differences were found between the damage in GaAs on one hand and Si and Ge on the other. In Si and Ge the number of defects and the strain increase linearly with dose up to the amorphous threshold. In GaAs the increase in these quantities is neither linear nor monotonic with dose. At a moderate damage level the GaAs crystal undergoes a transition from elastic to plastic behavior. This transition is accompanied by the creation of extended defects, which are not detected in Si or Ge.
Picosecond laser pulse irradiation of crystalline silicon
Authors: Merkle K. L. , Baumgart H. , Uebbing R. H. , Phillipp F.
Published: February 2003

Morphology changes introduced by picosecond laser pulses at λ = 532 nm and 355 nm in (111) and (100) silicon samples are studied by means of optical and high-voltage electron microscopy. Depending on energy fluence, orientation and wavelength, amorphous or highly defective regions may be created. From an analysis of damage thresholds and damage depth distributions it is concluded that melting and energy confinement precedes the formation of the structural changes.
Ultra-low-noise tunnel junction dc SQUID with a tightly coupled planar input coil
Authors: Ketchen M. B. , Jaycox J. M.
Published: February 2003

We present a new superconducting quantum interference device (SQUID) that combines ultra-low-noise performance with tight coupling to a useable input coil. The inductive loop of the SQUID consists of a superconducting square washer that is slit in a low inductance fashion from its central hole to an outside edge where two Josephson tunnel junctions are incorporated. The inductance of the SQUID is about 90 pH, and each junction has a critical current of 15 μA and a resistive shunt of 4.5 Ω. The 190-nH input coil is a planar spiral of 50 turns situated immediately above the washer and coupled to the SQUID with a coupling constant k2 of 0.86. The SQUID has a minimum coupled energy sensitivity of 19h at 4.2 K and 8h at 1.5 K, in good agreement with theory. The crossover between white and low frequency noise occurs at ∼250 Hz.
Resonantly enhanced vacuum ultraviolet generation and multiphoton ionization in carbon monoxide gas
Authors: Glownia James H. , Sander Robert K.
Published: February 2003

Competition between three-photon resonantly enhanced vacuum ultraviolet third-harmonic generation and six-photon multiphoton ionization using the A state in gaseous carbon monoxide is observed. Excitation spectra of the third-harmonic emission exhibit increasing blue shifts and broadening with increasing pressure due to the phase matching requirements. Estimates for the efficiency and tunability show that third-harmonic generation in carbon monoxide molecules is a promising source for coherent vacuum ultraviolet light.
cw optically pumped 12-μm NH3 laser
Authors: Rolland C. , Garside B. K. , Reid J.
Published: February 2003

A 30-W cw CO2 laser operating on the R(30) 9-μm transition is used to pump a ring laser cavity containing NH3. Emission at 12.08 μm is observed with cw output power of 180 mW. A Raman process is shown to be responsible for the gain at 12.08 μm.
Observation of flux trapping threshold in narrow superconducting thin films
Authors: Washington M. A. , Fulton T. A.
Published: February 2003

Narrow superconducting thin films cooled in a perpendicular low magnetic field (B⊥) are observed to trap magnetic flux at densities much less than the ρi0 = B⊥ /φi0 observed for superconducting films of large dimensions. Significant flux trapping does not occur until a threshold field B0⊥ is reached. B0⊥ increases with decreasing linewidth and with increasing distance from a superconducting ground plane.
Low-temperature release of ion-implanted helium from nickel
Authors: Poker D. B. , Williams J. M.
Published: February 2003

This letter presents data on the release of He from Ni at temperatures between 18 and 300 K after ion implantation of He at 18 K. The release occurred in two stages, a sharply peaked release near 50 K and a broad release that extended from 80 to 300 K. For He doses in the range of 5×1014–1.4×1016 cm−2 and shallow implantation depths (<1000 Å) the fraction released was 1.5% in the first stage and 4% in the second. For a dose of 4.4×1016 cm−2, the fraction released in the first stage was significantly higher. The activation energy for the first stage release was 0.11±0.02 eV for all doses.
Surface ripples on silicon and gallium arsenide under picosecond laser illumination
Authors: Fauchet P. M. , Siegman A. E.
Published: February 2003

We report experimental results on spontaneous periodic surface structures or ripples which occur on the surface of crystalline or ion-implanted semiconductors, using high-power picosecond laser pulses. We suggest that these surface ripples develop as the result of an exponentially growing interaction between the incident laser wave front and a scattered surface optical wave.
Femtosecond interferometry for nonlinear optics
Authors: Halbout J-M. , Tang C. L.
Published: February 2003

A technique of time-resolved interferometry capable of observing nonlinear optical phenomena down to 70 fs is presented. We report the direct observation of the rotational contributions to the nonlinear refractive index of molecular liquids using this technique. The subpicosecond dynamics of such a nonlinearity in CS2 are investigated. This technique can be readily extended to solids, in particular laser glasses.
Plasma-enhanced chemical vapor deposition of tungsten films
Authors: Chu J. K. , Tang C. C. , Hess D. W.
Published: February 2003

High-purity films of tungsten are deposited from tungsten hexafluoride and hydrogen using plasma-enhanced deposition (PED). At 400 °C deposition temperature, resistivities of ∼40 μΩ cm are attained. After annealing at 1100 °C, the resistivity falls to ∼7 μΩ cm. Below 400 °C, the as-deposited film stress is <6×109 dynes/cm2. Tensile, unlike tungsten, molybdenum films deposited by PED displayed high resistivities.
Organic-on-inorganic semiconductor contact barrier devices
Authors: Forrest S. R. , Kaplan M. L. , Schmidt P. H. , Feldmann W. L. , Yanowski E.
Published: February 2003

The organic compound 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) has previously been observed to undergo a large increase in conductivity on irradiation with energetic particle beams. In this letter, we describe the electrical characteristics of novel rectifying junctions employing unirradiated PTCDA vapor deposited onto 10-Ω cm p-Si substrates. The PTCDA-Si contact barrier has a height of φB = 0.74 eV. The resulting diodes undergo avalanche breakdown at VB = 230 V, and exhibit current densities at 1/2  VB of ⩽50  μA/cm2. In addition, the forward current-voltage (IF−V) characteristics are strongly dependent on the contact metal used on the top PTCDA surface. The best results obtained were for diodes employing Ti contacts which gave nonhysteretic, stable IF-V characteristics with an ideality factor of n = 1.7. Several properties of the as-deposited PTCDA are also discussed. The rectifying characteristics reported here, coupled with the properties of irradiated PTCDA, suggest many unique device applications.
Metal-oxide-semiconductor field-effect transistors fabricated in laterally seeded epitaxial Si layers on SiO2
Authors: Miyao M. , Ohkura M. , Takemoto I. , Tamura M. , Tokuyama T.
Published: February 2003

Metal-oxide-semiconductor field-effect transistors (MOSFET’s) were fabricated in laterally seeded epitaxial Si layers on SiO2, using cw Ar laser irradiation. FET’s were distributed in various regions of the epitaxial films grown on SiO2, as well as directly on a Si substrate. Electronic properties were found to be good when compared with that for bulk Si, even though mobility at the SiO2 edge was somewhat poor. The results are discussed in connection with the crystal qualities examined through use of optical and electron microscopy.
Low-temperature refractory metal film deposition
Authors: Solanki R. , Boyer P. K. , Collins G. J.
Published: February 2003

We have deposited uniform films of Mo, W, and Cr over large areas (>5 cm2) using UV laser photodissociation of their respective hexacarbonyls. The depositions were made at room temperature over pyrex and quartz plates, as well as silicon wafers. We have examined the resistivity, reflectivity, stress, and step coverage of these films.
Passivation of the dominant deep level (EL2) in GaAs by hydrogen
Authors: Lagowski J. , Kaminska M. , Parsey J. M. , Gatos H. C. , Lichtensteiger M.
Published: February 2003

We showed that hydrogen incorporated into single crystals of GaAs (by exposure of the crystals to hydrogen plasma) renders the major deep donor level (EL2) located at 0.82 eV below the conduction band at room temperature electronically inert. We attribute this passivation process to the interaction of hydrogen with the unsaturated bonds of the antisite AsGa defect (believed to be responsible for EL2) leading to the formation of stable As–H bonds.
Thermal oxidation of tantalum silicide in O2 and H2O
Authors: Saraswat Krishna C. , Nowicki Ronald S. , Moulder John F.
Published: February 2003

Thermal oxidation of TaSi2 in dry oxygen and steam has been investigated. 0.3-μm-thick films of tantalum silicide were deposited by cosputtering on high resistivity 〈111〉 silicon and oxidized silicon wafers. After a crystallization anneal in argon, the films were oxidized in dry O2 or steam at 1000 and 1100 °C. In all cases oxidation was observed. For TaSi2 deposited on Si, only the growth of SiO2 was observed, indicating that the Si diffused through TaSi2 before oxidation, and TaSi2 remained intact. In the case where TaSi2 was deposited on SiO2, it was actively involved in the oxidation process, resulting in the formation of SiO2 and Ta2O5.
Mass and energy distribution of particles sputter etched from Si in a XeF2 environment
Authors: Haring R. A. , Haring A. , Saris F. W. , de Vries A. E.
Published: February 2003

The sputtering of Si by 3-keV Ar+ ions under simultaneous exposure to a beam of XeF2 gas has been investigated. The masses and some energy distributions of the neutral particles emitted from the target have been determined by mass spectrometry and time of flight. We found the following Si-containing ions: Si+, SiF+, SiF+2, and SiF+3. The energy distributions of the sputtered particles cannot be explained by thermal desorption at the target temperature but can be interpreted as a collision cascadelike mechanism with a low surface binding energy.
Optical absorption of silicon between 1.6 and 4.7 eV at elevated temperatures
Authors: Jellison G. E. , Modine F. A.
Published: February 2003

The optical absorption coefficient of silicon for photon energies between 1.65 and 4.77 eV (750– 260 nm) has been determined at elevated temperatures (up to 700 °C) using polarization modulation ellipsometry. For photon energies below ∼3 eV (∼410 nm), the absorption coefficient increases exponentially with temperature from room 24° C to 700 °C, increasing by a factor of approximately 5 over that temperature range. The threshold for direct band-gap absorption moves to lower energies with increasing temperature.
Liquid phase epitaxial growth of lattice-matched Al0.48In0.52As on InP
Authors: Nakajima Kazuo , Tanahashi Toshiyuki , Akita Kenzo
Published: February 2003

The liquid phase epitaxial (LPE) growth condition to obtain lattice-matched Al0.48In0.52As on (100) InP was found. Using this growth condition, smooth and lattice-matched Al0.48 In0.52As layers could be grown for the first time on InP by the LPE method. The growth temperature near 800 °C was necessary to grow the ternary epitaxial layers. It was found by photoluminescence measurements that the energy gap of lattice-matched Al0.48 In0.52As was 1.42 eV.
Amplification of 70-fs optical pulses to gigawatt powers
Authors: Fork R. L. , Shank C. V. , Yen R. T.
Published: February 2003

We report a technique for amplifying pulses as short as 70 fs to gigawatt power levels while retaining the short duration of the incident pulse. Pulse recompression by a dispersive delay line is used to compensate temporal broadening by group velocity dispersion.
Formation of metastable supersaturated solid solutions in ion implanted silicon during solid phase crystallization
Authors: Narayan J. , Holland O. W.
Published: February 2003

We have investigated maximum solubility limits and extended defects in Si-Sb, Si-In, Si-Ga, Si-Bi, and Si-As systems after ion implantation and solid phase epitaxial growth in the temperature range 450-600 °C. The maximum concentration of solutes in ’’defect-free’’ layers were found to exceed the respective retrograde solubility limits by as much as a factor of 560 in Si-Bi system. The maximum concentrations depended upon the substrate temperature and the ion current during implantations, which presumably affected the degree of amorphousness or free energy of as- implanted silicon.
Laser-induced periodic surface damage and radiation remnants
Authors: Young Jeff F. , Sipe J. E. , Preston J. S. , van Driel H. M.
Published: February 2003

We report a detailed experimental study of the periodic surface damage induced by laser irradiation at 1.06 μm on nominally smooth Ge samples; we include novel observations of the damage obtained by studying its optical diffraction pattern, which reveals a previously unappreciated richness in the damage structure. The usual ’’surface scattered wave’’ explanation of the damage is criticized; we argue that the damage results from the electromagnetic fields generated by surface inhomogeneities but that, due to the presence of the interface between vacuum and bulk Ge, these fields are not radiative; these ’’radiation remnants’’ are discussed.
Use of selective annealing for growing very large grain silicon on insulator films
Authors: Colinge J. P. , Demoulin E. , Bensahel D. , Auvert G.
Published: February 2003

The selective annealing technique (laser annealing under a patterned antireflecting coating) has been successfully applied to the growth of very large (20×400 μm) silicon single crystals on SiO2. The grain boundary location is controlled by a conventional lithography step, and the grains obtained have a nearly perfect rectangular shape.
Low-dislocation-density GaAs epilayers grown on Ge-coated Si substrates by means of lateral epitaxial overgrowth
Authors: Tsaur B-Y. , McClelland R. W. , Fan John C. C. , Gale R. P. , Salerno J. P. , Vojak B. A. , Bozler C. O.
Published: February 2003

Single-crystal GaAs layers have been obtained by means of lateral epitaxial overgrowth seeded within stripe openings in a SiO2 mask over GaAs layers grown on Ge-coated Si substrates. Transmission electron microscope and scanning cathodoluminescence studies indicate that the laterally overgrown GaAs layers have a dislocation density of less than 104 cm−2, compared to 107–108 cm−2 for the GaAs layers grown directly on the Ge/Si substrates. Initial experiments indicate that the electrical properties of the laterally overgrown layers are comparable to those of conventional GaAs epilayers grown on single-crystal GaAs substrates.
Lamellar solidification of laser melted Co-Si films
Authors: Bösch M. A. , Dayem A. H. , Harrison T. R. , Lemons R. A.
Published: February 2003

Co-Si films deposited by coevaporation on silica substrates were melted with a scanned cw argon laser beam. A dramatic phase segregation is exhibited for compositions close to the eutectic composition. The observed morphology is an excellent example of lamellar eutectic solidification and is unusual for these high entropy of melting phases. The lamellae follow the temperature gradient produced by the scanned laser beam and delineate this gradient.
Charge transport by surface acoustic waves in GaAs
Authors: Hoskins Michael J. , Morkoç Hadis , Hunsinger Bill J.
Published: February 2003

The traveling wave potential wells, associated with a surface acoustic wave (SAW) generated in a multilayer epitaxial GaAs structure, are used to transport electrons at the velocity of sound in the buried channel formed by a Schottky-N-P layer configuration. A monolithic delay line based on the SAW transport concept is constructed and the time domain response of the delay line is presented. The SAW charge transport concept in GaAs is expected to be useful for the implementation of high-speed monolithic signal processors.
Compositional dependence of band-gap energy and conduction-band effective mass of In1−x−yGaxAlyAs lattice matched to InP
Authors: Olego D. , Chang T. Y. , Silberg E. , Caridi E. A. , Pinczuk A.
Published: February 2003

The band-gap energy and the electron effective mass of In1−x−yGaxAlyAs lattice matched to InP have been determined as a function of Al content. From photoluminescence measurements we obtain Eg(eV) = (0.76±0.04)+(1.04±0.10)y+(0.87±0.13)y2. The electron effective mass is determined from the plasma frequencies measured with Raman scattering in n-type samples. Its compositional dependence is given by m* = (0.0427±0.0015)+(0.0683±0.0007)y.