bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron-beam-driven instability in a solid
Authors: Perry F. C. , Mix L. P.
Published: February 2003

A relativistic electron beam (REB) accelerator was used to generate a shock wave (6–10 kbar) in a solid aluminum plate, and the tensile wave following the compressive wave produced an instability of the back surface of the plate. The wavelength of the instability, observed by holographic interferometry, and the measured negative acceleration of the solid-gas interface were used in a modified theory of Taylor instability to determine a value of 1.7×103 P for the viscosity of aluminum which was in reasonable agreement with a previously reported value. It is suggested that the mechanism of Taylor instability can qualitatively explain the obervation in a previous experiment of a distribution of particle velocities at a surface of a solid upon arrival of a very high-amplitude (∼1 Mbar) shock wave.
Reduction of surface erosion caused by helium blistering: Microstructural effects
Authors: Das S. K. , Kaminsky M. , Rossing T. D.
Published: February 2003

An attempt has been made to determine if a suitable microstructure (e.g., grain size, dispersion of oxide particles in a metal matrix) of a material can be found to reduce the helium buildup and subsequent blistering in near-surface regions. A comparison of the surface erosion due to helium blistering in aluminum and sintered aluminum powder (SAP) has been made for irradiation at room temperature with 100-keV He+ ions to a dose of 1.0 C/cm2. The results show high reduction in erosion rate in SAP by more than 3 orders of magnitude as compared to the erosion rate in pure aluminum.
GaAs electro-optic directional-coupler switch
Authors: Campbell J. C. , Blum F. A. , Shaw D. W. , Lawley K. L.
Published: February 2003

We report the fabrication and testing of a GaAs electro-optic directional-coupler (EDC) switch in which the fraction of light coupled from one waveguide channel to the other can be controlled by an applied electric field. Ninety-five percent amplitude switching and a maximum extinction ratio of 13 dB have been observed in an EDC switch, having a minimum 3-dB bandwidth of ≳100 MHz and a drive power per unit bandwidth of <180 μW/MHz.
A new type of voltage-controlled negative resistance in thin samples of InSb
Authors: Kamakura Katsutoshi , Mutoh Nobuo
Published: February 2003

A new type of voltage-controlled negative resistance is observed in very thin samples of n-InSb in a high electric field in the region of avalanche breakdown (E≳600 V/cm) and a transverse high magnetic field (B≳1 kG) at 77 K. The negative resistance is observed only in thin samples whose thickness is less than about 30 μm regardless of the length. The mechanism of negative resistance seems to be different from proposed effects such as trapping of hot electrons, Gunn effect, and the acoustoelectric domain effect.
Anomalous diffusion of arsenic in silicon during low-temperature heat treatment
Authors: Shibayama H. , Masaki H. , Hashimoto H.
Published: February 2003

It was found that diffusion of arsenic, and boron underneath the arsenic-diffused layer, was accelerated during low-temperature heat treatment. This diffusivity is extremely large in comparison to the normal one, and depends on the treatment time. The effective diffusion coefficients of arsenic at 700 °C are 1×10−16 cm2/sec for 5 h and 7×10−18 cm2/sec for 170 h. Such a phenomenon may be due to the excess vacancies formed during these treatments. This effect also causes the emitter dip effect in the npn transistor using arsenic for the emitter impurity.
Development of an efficient 9-kW 496-μm CH3F laser oscillator
Authors: Cohn D. R. , Fuse T. , Button K. J. , Lax B. , Drozdowicz Z.
Published: February 2003

A 496-μm CH3F cavity laser characterized by an average power of 9 kW and predominant single longitudinal mode operation with a linewidth of 28 MHz has been constructed. The power conversion efficiency of the laser (CH3F power out/CO2 pump power in) is on the order of 1.5×10−3. The CH3F gas is pumped in a zig-zag fashion by the CO2 laser radiation.
Electrically switched optical directional coupler: Cobra
Authors: Papuchon M. , Combemale Y. , Mathieu X. , Ostrowsky D. B. , Reiber L. , Roy A. M. , Sejourne B. , Werner M.
Published: February 2003

We report the realization, in titanium-diffused lithium niobate, of an integrated optical switch/modulator consisting of an active directional coupler with a novel electrode configuration. Efficient switching is observed with 6 V applied.
Output coupling and distributed feedback utilizing substrate corrugations in double-heterostructure GaAs lasers
Authors: Scifres D. R. , Burnham R. D. , Streifer W.
Published: February 2003

Conventional double-heterostructure lasers with a thin n-Ga1−yAlyAs layer grown on a periodically corrugated n-GaAs substrate have been operated at room temperature. The evanescent tail of the guided mode interacts with the substrate corrugation to produce both distributed feedback and output coupling perpendicular to the waveguide. A single polarized low-divergence (0.65°×10°) output beam at 8825 Å radiated normal to the waveguide was obtained from such a diode with cleaved end facets at a threshold current of 4.1 kA/cm2.
Surface-induced molecular orientation of liquid crystals by carboxylatochromium complexes
Authors: Matsumoto Shoichi , Kawamoto Masahiro , Kaneko Nagao
Published: February 2003

Tetrachloro–μ-hydroxo–μ-carboxylatodichromium (III) complexes have been used to induce homeotropic alignment of nematic, smectic, and large-pitch cholesteric liquid crystals. A dynamic scattering degradation test has shown that this orientation is remarkably stable.
High-field diffusion of electrons in silicon
Authors: Canali C. , Jacoboni C. , Ottaviani G. , Alberigi-Quaranta A.
Published: February 2003

With the time-of-flight technique we have measured the longitudinal diffusion coefficient of electrons in silicon at 300 K for fields from Ohmic up to 50 kV/cm. The results have been interpreted by means of Monte Carlo calculations with a theoretical model which includes the many-valley (ellipsoidal and nonparabolic) structure of the band, acoustic intravalley, and several f and g intervalley scattering mechanisms.
Laser action on the 2Σ+1/2→2Σ+1/2 bands of KrF and XeCl
Authors: Ewing J. J. , Brau C. A.
Published: February 2003

This letter describes two new lasers operating on the 2Σ+1/2→2Σ+1/2 bands of XeCl (at 308 nm) and KrF (at 249 nm). Pumping was achieved by high-intensity electron beam excitation of high-pressure Ar containing small amounts of Xe and Cl2 or Kr and F2. An efficiency of about 0.4% was observed in the initial experiments on KrF, and higher efficiencies appear possible.
Electro-optic effects in the optically active compounds Bi12TiO20 and Bi40Ga2O63
Authors: Fox A. J. , Bruton T. M.
Published: February 2003

The electro-optic effects in the optically active 23 class compounds Bi12TiO20 (BTIO) and Bi40Ga2O63 (BGAO) have been investigated. Measurements were made of the electro-optic and electrogyration coefficients using longitudinal and transverse modes. Novel techniques employing a servo-driven Soleil compensator were used to obtain these coefficients. A value of η=17×10−12 rad m/V was obtained for the electrogyratory coefficient in the BTIO compound.
The possibility of an efficient tunable molecular iodine laser near 340 nm
Authors: McCusker M. V. , Hill R. M. , Huestis D. L. , Lorents D. C. , Gutcheck R. A. , Nakano H. H.
Published: February 2003

We have observed intense band emissions between 340 and 344 nm from electron-beam-excited mixtures of high-pressure argon gas and iodine vapor. This emission appears to be from molecular iodine. Using the 357.6-nm band from an Ar/N2 mixture as a calibration, we have measured the fluorescence yield in this wavelength region to be 70±24%. From this we computed an over-all fluorescence energy efficiency of 13±4%. Based on these observations, we suggest the feasibility of an efficient high-energy electron-beam-pumped argon-iodine laser. The gain of such an argon-iodine laser should be comparable to that of the Ar/N2 second positive laser.
Integral Auger information via tailored modulation techniques
Authors: Springer R. W. , Pocker D. J. , Haas T. W.
Published: February 2003

A simple technique for the measurement of Auger N (E) peak heights and areas [I (E)] directly at the phase lock amplifier output has been developed. It is implemented by tailoring the modulation waveform to instrument response function and dynamic background subtraction constraints. Comparisons of results of this approach with those of conventional analog integration show essentially perfect proportionality.
Investigation of defects and striations in as-grown Si crystals by SEM using Schottky diodes
Authors: de Kock A. J. R. , Ferris S. D. , Kimerling L. C. , Leamy H. J.
Published: February 2003

As-grown silicon crystals are investigated in the scanning electron microscope using Schottky barrier diodes in the electron-beam-induced current mode. Dislocations, A- and B-type swirl defects, as well as dopant striations are detected. In high-resistivity crystals (∼1000 Ω cm) variations in dopant concentration of 1012 cm−3 are readily revealed. Hydrogen doping is found to eliminate preferential recombination at microdefects. It is established that bulk stresses due to carbon striations have no detectable electrical effect.
Diatomic versus atomic secondary ion emission
Authors: Wittmaack K. , Staudenmaier G.
Published: February 2003

The yield ratio of diatomic versus atomic secondary ion emission from metals and semiconductors has been studied using two different mass spectrometers. Under ultrahigh vaccum conditions and with argon primary ions, yield ratios in excess of unity were observed for a variety of elements at secondary ion energies below about 10 eV.
Stimulated emission from CO+ pumped by charge transfer from He+2 in the afterglow of an e-beam discharge
Authors: Waller R. A. , Collins C. B. , Cunningham A. J.
Published: February 2003

Stimulated emission from the B2Σ state of CO+ has been observed as a consequence of the charge transfer reaction between He+2 and CO in the afterglow of a Febetron 706 discharge into 3 atm of helium containing 1.0 Torr of carbon monoxide. Peak gains of the order of 0.08 cm−1 were found for the (0,2) vibrational component of the B2Σ→X2Σ transition at 2470 Å by directly measuring the time-resolved amplification of suitably filtered light from a xenon flashlamp. Correspondingly smaller gain, persisting for several hundred nanoseconds, was found for the (0,0) and (0,1) vibrational components of the B2Σ→A2Π transitions at 3954 and 4210 Å, respectively.
Cross-sectional electron microscopy of silicon on sapphire
Authors: Abrahams M. S. , Buiocchi C. J.
Published: February 2003

Cross sections of (100)Si/(012)sapphire were examined by transmission electron microscopy. The foil plane was (011)Si and contained the [1̄00]Si growth direction. The number of faults (i.e., microtwins and isolated stacking faults) per cm measured in the [022]Si direction, FD, decreases with increasing distance d from the silicon/substrate growth interface according to the equations FD= (3.1×107)/d0.63 (440⩽d⩽2400 Å), and FD= (1.3×1011)/d1.7 (2400?d?4.3×104 Å). Misfit dislocations were not observed, and no evidence for the presence of an Al-bearing phase was seen in the proximity of the interface.
Chemical trends in oxygen uptake rates at the ordered surfaces of tetrahedrally coordinated compound semiconductors
Authors: Mark Peter , Creighton William F.
Published: February 2003

It is observed that oxygen uptake at ordered free surfaces of tetrahedrally coordinated semiconductors decreases with increasing bonding ionicity. This behavior is compared with the dependence of the contact potential at a Schottky barrier on the semiconductor bonding ionicity, and an explanation based on the Mead–Spitzer and Phillips models is suggested.
Embedded heterostructure epitaxy: A technique for two-dimensional thin-film definition
Authors: Samid I. , Lee C. P. , Gover A. , Yariv A.
Published: February 2003

Selective multilayer epitaxial growth of GaAs-Ga1−xAlxAs through stripe openings in Al2O3 mask is reported. The technique results in prismatic layers of GaAs and Ga1−xAlxAs ’’embedded’ in each other and leads to controllable uniform structures terminated by crystal faces. The crystal habit (shape) has features which are favorable for fabrication of cw injection lasers, laser arrays, and integrated optics components which require planar definition.
High-power xenon fluoride laser
Authors: Ault E. R. , Bradford R. S. , Bhaumik M. L.
Published: February 2003

High-power laser emission has been observed from xenon fluoride (XeF) at 351.1 and 353.1 nm. A peak laser power of 0.5 MW was obtained by using a mixture of Ar, Xe, and NF3 in the ratio of 250 : 25 : 1 at a total pressure of 1.7 atm. The laser gas was excited by a 1-MeV 20-kA electron beam for a pulse duration of 20 nsec. Energy deposited in the gas by the electron beam was estimated to be 1 J which gives a laser efficiency of 0.5%. Using a coaxial electron gun, an 80-mJ 100-nsec pulse was obtained with an efficiency of 3%.
Magnetic insulation and microwave generation
Authors: Ott Edward , Lovelace R. V.
Published: February 2003

A relativistic self-consistent equilibrium is found for the magnetic insulation of a diode for conditions where the voltage rise time is long compared to the cyclotron period. Instability of the magnetic insulation equilibrium may allow high-power pulsed microwave generation in magnetronlike configurations.
Mixed metal vapor phase matching for third-harmonic generation
Authors: Bloom D. M. , Young J. F. , Harris S. E.
Published: February 2003

Phase matching for frequency tripling of 1.06 μm is demonstrated in a homogeneous mixture of sodium and magnesium vapor. For phase matching, the ratio of Mg to Na vapor pressures is 2 : 1. This ratio is about 1/75 of the ratio of Xe to Na required for phase matching.
Spectral narrowing and electro-optical tuning of a pulsed dye laser by injection locking to a cw dye laser
Authors: Turner J. J. , Moses E. I. , Tang C. L.
Published: February 2003

It is shown that the single-element electro-optical birefringent filter can be used to tune the relatively high-gained flashlamp-pumped pulsed dye laser across the entire dye emission band, but the resulting laser line width is relatively wide as might be expected. However, this line width could be drastically reduced without losing the tunability by injection locking the pulsed laser to an electro-optically tuned cw dye laser. The beam direction, collimation, spectral width, and stability of the pulsed laser can, therefore, all be precisely controlled through the cw laser beam.
Technique for producing ’’good’’ GaAs solar cells using poor-quality substrates
Authors: Hovel H. J. , Woodall J. M.
Published: February 2003

Relatively good GaAs solar cells can be made from poor-quality substrates by making the junction deep (≳1 μ) instead of shallow and by ’’leaching’’ both the pGaAs and nGaAs regions during the growth process. AM0 efficiencies of 14.7% (19% AM1) have been obtained from substrates with starting substrate diffusion lengths of 0.6 μ.
Piezochemisorption effect: A new method for modulating the rate of chemisorption on polar crystals
Authors: Lagowski J. , Gatos H. C. , Sproles E. S.
Published: February 2003

It was found that mechanical strain has a striking effect on the chemisorption rate of the polar surfaces of ZnO. Depending on its sign, a strain as low as 10−3 can increase or decrease the rate of chemisorption by more than an order of magnitude. This piezochemisorption effect was shown to be consistent with a model based on strain-induced changes in the height of the surface potential barrier and the surface barrier-controlled transfer of electrons between the semiconductor and the adsorbed species.
Large electrostrictive effect in doped alkali halide crystals
Authors: Burkard H. , Känzig W.
Published: February 2003

The electrostriction of alkali halide crystals containing substitutional impurities (the paraelectric systems KCl:Li+, NaBr:F−, RbCl:Ag+, RbBr:Ag+, KCl:OH−, and the system KBr:Li+) has been measured for concentrations of the order 1017–1018 cm−3. Some of these systems exhibit a giant almost temperature-independent electrostrictive effect that does not saturate.
Calculated energy distributions for light 0.25–18-keV ions scattered from solid surfaces
Authors: Robinson J. E. , Harms A. A. , Karapetsas S. K.
Published: February 2003

Scattered energy distributions are calculated for light ions incident on Nb and Mo surfaces of interest for controlled nulcear fusion reactors. The scattered energy is found to vary as a function of the reflection coefficient between a multiple-collision limit at low energies and a single-collision Rutherford scattering limit at high energies. High-energy peaking of the scattered particle distributions is also found for low incident energies.
Tertiary defects in phosphorus-implanted silicon
Authors: Tamura M. , Yoshihiro N. , Ikeda T.
Published: February 2003

Transmission electron microscopic observations have been made on dislocations generated in high-dose (1×1015–3×1016 ions/cm2) phosphorus-implanted (111) silicon wafers followed by 1100 °C isothermal annealing in inert (dry N2) and oxidizing (wet O2) atmospheres. The generation and movement of dislocations in a wafer are strongly influenced by atmospheres during annealing. In dry-N2 annealing, the critical ion dose for generation of dislocation networks is 1×1016 ions/cm2, which is three times higher than that in wet-O2 annealing. Also, dislocations move down to greater depths in a wafer after annealing in a wet-O2 atmosphere, while in dry-N2 annealing their location in a wafer is usually unchanged.
Phase separation in silicon oxides as seen by Auger electron spectroscopy
Authors: Johannessen J. S. , Spicer W. E. , Strausser Y. E.
Published: February 2003

Auger electron spectroscopy has been used in a study of chemical structure effects in silicon oxides caused by changes in the over-all stoichiometry. Thermally grown silicon dioxide and vacuum-deposited unsaturated silicon oxides SiOx were investigated. Chemical shifts in the Si KLL spectra are interpreted in terms of phase separation in SiOx for 0<x<2. The preferred phases are Si and SiO2. We believe that the minor component exists as microscopic inclusions, larger than some 15–20 Å, in the predominant component.
Photolytic detection of H2S with a PbSe sensor
Authors: Young J. J. , Zemel J. N.
Published: February 2003

The sensitivity of PbSe epitaxial films to atomic hydrogen was used to detect the photodissociation of H2S by ultraviolet radiation. It was also observed that H2S would cause a response similar to that of atomic hydrogen, suggesting that H2S dissociates on the PbSe surface.
The role of discrete plasma initiation sites in the high-intensity laser irradiation of surfaces
Authors: Nielsen P. E.
Published: February 2003

The total impulse delivered to solid surfaces through irradiation by CO2 lasers of intensity greater than 107 W/cm2 and pulsewidth of order 10−5 sec agrees well with theories which invoke the ignition of laser-supported detonation waves whose pressure scales on the 2/3 power of laser intensity, while the measured peak pressure under the irradiated area scales much more strongly with intensity. It is shown that these seemingly contradictory results may be reconciled through a model in which detonation waves are formed from discrete initiation sites whose size distribution determines the peak pressure scaling.
Some properties of granular thin films of high-field superconductors
Authors: Jones Harris C.
Published: February 2003

The resistance as a function of temperature, the superconducting critical temperature, and the upper critical field of NbN and Nb3Ge thin films have been measured. These measurements may be explained in terms of a model of a granular superconductor. The properties of NbN and Nb3Ge may be universal characteristics of high-field granular superconductors.
Sulfur isotope enrichment by dissociative electron attachment
Authors: Allen J. E. , Keefer D. R. , Person W. B.
Published: February 2003

A mechanism is proposed for sulfur isotope enrichment experiments with lasers combining the selective vibrational heating capabilities of the laser with the electron attachment properties of the SF6 molecule. It is suggested that isotope enrichment may be achieved by selective vibrational heating of one isotopic molecule by the laser, followed by its dissociative electron capture and subsequent removal from the mixture. A reasonable estimate for the extent of selective vibrational heating, together with a slight extrapolation of the known temperature dependence for the SF−5/SF6− branching ratio, indicates that enrichment ratios of the order of 4500 may be achievable by this process.
Influence of γ phase upon thermally stimulated current spectra in polyvinylidene fluoride
Authors: Pfister G. , Prest W. M. , Luca D. J. , Abkowitz M.
Published: February 2003

The presence of the γ crystalline phase in polyvinylidene fluoride is shown to enhance the thermally stimulated current response around room temperature by at least 50 times. Infrared absorption and thermally stimulated current are correlated.
Heterojunction band discontinuities
Authors: Shay J. L. , Wagner Sigurd , Phillips J. C.
Published: February 2003

The discontinuity ΔEc=0.56 eV in the conduction band edge at n-CdS/p-InP junctions is reported. This discontinuity and others are compared with photoemission data and with Van Vechten’s extension of these data to many tetrahedrally coordinated semiconductors. Agreement between measured discontinuities and theoretical predictions is very good. Predictions are made for band parameters pertinent to interfaces involving AIIBIVCV2 compounds with zinc blende, chalcopyrite, or wurtzite crystal structures.
Efficient low-voltage electroluminescent devices by tunnel injection of holes
Authors: Clark M. D. , Baidyaroy S. , Ryan F. , Ballantyne J.M.
Published: February 2003

Efficient tunnel injection of holes into n-type semiconductors has been achieved with evaporated metal-insulator structures on single-crystal GaAs and CdS. Nearly ideal tunneling of holes is observed, with abrupt turn-on of electroluminescence under dc applied voltage comparable to the semiconductor band gap, and internal quantum efficiency on the order of unity.
Smooth and coherent layers of GaAs and AlAs grown by molecular beam epitaxy
Authors: Chang L. L. , Segmüller Armin , Esaki L.
Published: February 2003

Periodic ultrathin layers of GaAs and AlAs with a few periods have been grown by molecular beam epitaxy under computer control. For such structures, x-ray scattering measurements at small angles show a series of principal and secondary interference peaks. The results are in good agreement with theoretical calculations, giving evidence to a degree of smoothness and coherency on the scale of atomic dimensions. Furthermore, the nonuniformity in thickness over a relatively large sample area is shown to be governed by the geometry of the growth system.
Raman cross-section determination by direct stimulated Raman gain measurements
Authors: Kincaid B. E. , Fontana J. R.
Published: February 2003

The stimulated Raman gain of the Q branch of the first vibrational transition of atmospheric N2 was measured with a nonfocused primary-laser single-pass amplifier configuration. The Raman signal which was amplified over a path of 8.53 m was provided by a near-ir dye laser pumped by the ruby primary laser. The Raman cross section was determined from the measured gain.
Profile and groove-depth control in GaAs diffraction gratings fabricated by preferential chemical etching in H2SO4-H2O2-H2O system
Authors: Tsang Won-Tien , Wang Shyh
Published: February 2003

We studied in detail the fabrication of diffraction gratings in GaAs by preferential chemical etching and demonstrated that different grating profiles can be obtained by proper choice of substrate orientation and direction of grating-mask groove openings or by controlling the width of these groove openings and/or etching time. We have also obtained experimental curves relating the etched groove depth to etching time for gratings with different periodicities at different etchant temperatures. In our experiments, the H2SO4-H2O2-H2O system was used as the preferential etchant together with Shipley AZ-1350J as the resist. This combination enables us to use the resist grating directly as a protective mask during chemical etching.
Effects of hydrogen contamination on the localized states in amorphous silicon
Authors: Malhotra A. K. , Neudeck G. W.
Published: February 2003

The effects of incorporating hydrogen into vacuum-evaporated amorphous silicon films as measured by the field-effect conductance change is reported. Analysis of the data indicates that the density of localized states near the Fermi level decreases from 1×1020/cm3 eV to 2.8×1019/cm3 eV as the partial pressure of hydrogen during vacuum evaporation is increased from 7×10−6 to 6×10−5 Torr, with all other sample preparation procedures fixed. Under the same conditions the resistivity increases as the partial pressure of hydrogen is increased.
Boron-implanted profiles in diamond
Authors: Blanchard B. , Combasson J. L. , Bourgoin J. C.
Published: February 2003

Boron ions with energy ranging from 40 to 250 kev have been implanted at room temperature in type-IIa diamonds with doses of 1015 and 1016 cm−2. The boron profiles have been measured using an ion analyzer. These profiles are compared with profiles calculated using Winterbon’s theory. Reasonable agreement between experimental and theoretical profiles is obtained for the electronic stopping cross section measured by Omrod et al. up to about 180 keV.
Distribution across the channel of defects induced by nitrogen bombardment in silicon
Authors: Baeri P. , Campisano S. U. , Ciavola G. , Foti G. , Rimini E.
Published: February 2003

Silicon crystals have been implanted at room temperature with 3.2×1015 ions/cm2 of 300-keV N+. The spatial distribution of displaced atoms has been determined by the backscattering energy spectra as a function of the crystal tilting angle with respect to the 〈111〉 axis. The changes in the extracted depth profiles have been correlated to the nonuniform distribution of defects across the channel. The radial distribution of displaced atoms has been determined on the basis of the flux-peaking treatment for impurity lattice location.
Laser-induced breakdown and nonlinear refractive index measurements in phosphate glasses, lanthanum beryllate, and Al2O3
Authors: Smith W. Lee , Bechtel J. H.
Published: February 2003

We present results of measurements of the laser-induced dielectric breakdown threshold in two phosphate composition laser glasses, in lanthanum beryllate:Nd, and in Al2O3. The nonlinear refractive indices for these materials are also presented. The measurements were made with single 30-psec 1.064-μm pulses. The results are compared with those for other laser materials in the 1.06-μm spectral region.
Diffraction from laser-induced deformation on reflective surfaces
Authors: Koo Jackson C. , Slusher Richart E.
Published: February 2003

Diffraction from laser-induced deformations on reflective surfaces is described as a model for an observed decrease in surface reflectivity immediately preceding surface damage. Experimental measurements of reflected laser radiation at large angles from copper and silicon surfaces are in qualitative agreement with this diffraction model.
Transparent electrode properties of cadmium stannate
Authors: Haacke G.
Published: February 2003

Thin films of semiconducting n-type cadmium stannate (Cd2SnO4) have been coated onto different substrate materials by rf sputtering. The films are transparent in the visible and near-infrared part of the optical spectrum and electrically conductive. Conductivities as high as 6500 Ω−1 cm−1 have been achieved. Transparent electrode coatings can be prepared which have 1 Ω/square electrical sheet resistance and 85% average optical transmission between 5000 and 6500 Å.
Comparison of interface-state buildup in MOS capacitors subjected to penetrating and nonpenetrating radiation
Authors: Winokur Peter S. , Sokoloski Martin M.
Published: February 2003

Metal-SiO2-Si capacitors under positive bias were subjected to penetrating Co60 γ and nonpenetrating 10.2-eV uv radiation. High-frequency 1-MHz and quasistatic C-V curves were recorded before and after irradiation, and interface-state densities over the Si band gap were calculated from these curves by using the Terman, Berglund, and Castagne techniques. The nature and magnitude of the buildup of interface states were similar for both types of irradiation, demonstrating that the buildup is not related to the direct interaction of radiation at the interface or a structural modification of the SiO2 layer, but to the production of electron-hole pairs in the oxide and the subsequent transport of holes to the oxide-semiconductor interface. The buildup of interface states under irradiation saturated at ∼5×105 rad (SiO2).
Single-crystal work-function and evaporation measurements of LaB6
Authors: Swanson L. W. , Dickinson T.
Published: February 2003

Retarding potential and Richardson work functions of 2.28±0.03 and 2.47±0.06 eV, respectively, have been measured for the (100) face of LaB6. Auger electron spectra of the thermally cleaned surface gave a B/La ratio of 2.3–2.6. Mass spectrometric measurements showed the evaporating species from a clean LaB6 (100) surface to be atomic La and B in near-stoichiometric proportions. Activation energies for the vaporization of La and B were 6.3±0.3 and 6.8±0.3 eV, respectively.
Laser light absorption measurements in an interaction-produced plasma column
Authors: Pincosy P. A. , Bournot P. , Dufresne D. , Caressa J. P. , Autric M.
Published: February 2003

100 J of 10.6-μ laser energy produced in a 1.5-μs pulse was focused to a 2-mm-diam spot by a 50-cm-focal-length mirror. A plasma was created by breakdown in the 70-ns gain-switched peak of the pulse where the light flux becomes greater than 1010 W/cm2. The plasma column subsequently created in 5–20 Torr of hydrogen by the absorbed light energy was observed by 5-ns exposure and streak photographs. The aspect of beam trapping is demonstrated by measurements of the transmitted light intensity radial distribution and significant energy absorption is shown by the measurement of transmitted energy.
A new class of efficient low-pressure gas discharges with high radiation output per unit volume
Authors: Hasker J.
Published: February 2003

A considerable increase of the axial electric field together with a modest increase of the electron temperature can be obtained by the introduction of a recombination structure (e.g., glass wool) into the discharge space. The effect is shown by experiments on mercury–rare-gas discharges and interpreted in terms of enhanced recombination of ions and electrons. As an application, it is shown that the luminous flux per unit volume of usual fluorescent lamps can be doubled, while maintaining high over-all luminous efficacy. Moreover, the construction of efficient fluorescent lamps with approximately the dimensions of an incandescent lamp has become feasible.
A compact 50-J CO2 TEA laser with VUV preionization and the discharge mechanism
Authors: Browne P. F. , Webber P. M.
Published: February 2003

A design is reported for a compact and simply constructed CO2 TEA laser giving pulses of up to 50 J with 0.1-μs duration from a discharge of dimensions 45×6×6 cm3. The gas is preionized by VUV irradiation from two lines of 34 series arcs to either side of the uniform field electrodes to which potentials of +50 kV and −50 kV are applied. The mechanism of preionization and the conditions for a uniform discharge are considered.
Capacitance and R-C time constant of a nearly pinched-off semiconducting channel in the high-frequency regime
Authors: Lehovec Kurt , Zamani Nasser
Published: February 2003

The gate capacitance of a nearly pinched-off semiconducting channel located between gate and substrate depletion layers is derived for the high-frequency regime in which the substrate charge does not change with ac channel charge. The distance corresponding to the inverse gate capacitance exceeds the gate depletion layer width, and the R-C time constant per unit channel length approaches the inverse of the product of channel carrier mobility and voltage equivalent of temperature. Ordinary C-V analysis at high frequency provides an artifactitious impurity profile which is fairly independent of the doping concentration and of the substrate and which varies in proportion to absolute temperature. Reconstruction of the true impurity profile from this artifactitious profile is discussed.
Fast-triton detector for laser fusion
Authors: Brysk H. , Mayer F. J.
Published: February 2003

A triton time-of-flight detector consisted of a CD2 foil in front of a shielded scintillator-photomultiplier. In neutron-generating laser-fusion experiments with DT gas inside glass microspheres, no substantial number of tritons occurred in the velocity range corresponding to the observed ’’fast’’ (glass) ions. Streaming can be excluded as the primary mechanism for neutron production.
Time-dependent translational velocity of magnetic bubble domains
Authors: Vella-Coleiro G. P.
Published: February 2003

The translational motion of magnetic bubble domains in a LuGdAlFe garnet film has been studied by high-speed photography. It was found that the average bubble velocity during a field gradient pulse is strongly dependent on the pulse duration τ, varying from 4200 cm/sec at τ=100 nsec to 1700 cm/sec at τ=500 nsec, at a field difference across the bubble diameter of 9.3 Oe. Large overshoots were observed at τ=500 nsec, but were greatly reduced at τ=100 nsec.
Magnetic properties of amorphous Tb-Fe thin films prepared by rf sputtering
Authors: Mimura Yoshinori , Imamura Nobutake
Published: February 2003

The magnetic properties of amorphous TbxFe1−x films prepared by rf cosputtering were studied. For 0.15<x<0.28, the films have uniaxial magnetic anisotropy normal to the film plane sufficient to stabilize cylindrical domains. The Curie temperature Tc and the coercivity Hc were measured as a function of composition. Tc increases monotonically with increasing Tb content in the alloy films in the region 0.1 < x<0.5. Hc is about one order of magnitude large, in contrast with amorphous Gd-Fe films at room temperature, and it increases further at low temperatures. Amorphous Tb-Fe films have a high potential for thermomagnetic recording using the Curie temperature because of the large Hc (1–5 kOe) and the low Curie temperature (∼120°C).
Ultrasonic waves in sandwiched fluid film
Authors: Miyano K. , Shen Y. R.
Published: February 2003

Using optical diffraction, we have measured the phase velocities of various ultrasonic modes in water films of different thicknesses sandwiched between two glass plates. The results agree well with theory.
Microwave emission from a magnetized plasma heated by a short-pulsewidth relativistic electron beam
Authors: Okamura R. , Nakamura Y. , Kawashima N.
Published: February 2003

Microwave emissions are observed with a long time duration after a beam turn-off from a magnetized plasma that is heated by a high-intensity short-pulsewidth relativistic electron beam (500 keV, 2 kA, 3 ns). The emission has a frequency spectrum which has peaks near cyclotron harmonics (f=nfce, n=2, 3,...). These microwave emissions can be attributed to electrostatic waves excited by hot electrons which are created in the beam-plasma interaction.
Stimulated emission on Nx(’’A-line’’) recombination transitions in nitrogen-implanted GaAs1−xPx(x≈0.37)
Authors: Wolford D. J. , Streetman B. G. , Nelson R. J. , Holonyak N.
Published: February 2003

Stimulated emission (4.2 °K) on the NX band recombination transition (formerly identified as NN-pair band) in N-implanted GaAs1−xPx(x≈0.37) is reported. The N is implanted (300 °K) at 200 keV to a peak concentration nN∼5×1018 cm−3 (depth 3600 Å), and to remove damage the crystal is later annealed at 950 °C for 0.5 h. The laser operation observed is the first involving an implanted isoelectronic trap, and occurs on the NX band at higher alloy composition than for any previous case.
Effects of interfacial oxide layers on the performance of silicon Schottky-barrier solar cells
Authors: Lillington D. R. , Townsend W. G.
Published: February 2003

Measurements have been made of the electrical and optical properties of Au–n-type silicon Schottky-barrier solar cells (SBSC) in which the metal and semiconductor are separated by a thin interfacial oxide layer ∼10–23 Å thick. Measurements of the V-I characteristics showed that the value of Voc is increased by up to 38% and the maximum conversion efficiency by as much as 35% when compared with cells having no grown oxide layer.
Amorphous silicon p-n junction
Authors: Spear W. E. , Le Comber P. G. , Kinmond S. , Brodsky M. H.
Published: February 2003

The preparation of an all-amorphous thin-film p-n junction is described. The a-Si films were produced by the glow discharge decomposition of silane, mixed with trace amounts of donor or acceptor impurities. The current-voltage characteristics of the junction were investigated in the range from 150 to 300 K.
Ion-implanted acoustic-surface-wave resonator
Authors: Hartemann P.
Published: February 2003

An acoustic-surface-wave resonator using a single periodic grating is described. A 633-line grating was obtained by ion implantation in quartz (Y,X) with a reflection coefficient larger than 99% at about 125 MHz. An interdigital transducer deposited in the middle of this grating was found to have an input impedance that depended upon the acoustic characteristics of the array. A peak impedance was obtained as a result of the buildup of resonance in the grating and was used to stabilize the frequency of the conventional L-C oscillator. In this case, the temperature stability of the oscillator is equal to that of the quartz substrate, that is, 22×10−6/deg.
GaAs reflection photocathodes grown by metal alkyl vapor phase epitaxy
Authors: Allenson M. , Bass S. J.
Published: February 2003

GaAs reflection photocathodes grown by vapor-phase epitaxy using trimethyl gallium and arsine have been activated to a maximum sensitivity of 1150 μA 1m−1. The material is of high quality and has diffusion lengths and surface escape probabilities which are comparable with those measured for liquid-phase epitaxial material.
Aging effects in Si-doped Al Schottky barrier diodes
Authors: Reith T. M.
Published: February 2003

Schottky barrier diodes made with Si-doped Al metallization on n-type Si exhibit aging at temperatures between 200 and 300 °C. The barrier height of these devices depends on the square root of time. A crystallized layer of Si on the devices, grown from the Al-Si metal, contains a certain amount of Al, which acts as a p-type dopant. The aging of the diodes is a direct result of variations in the amount of this Al, about which information can therefore be inferred from the kinetics of the aging process. The results are compared to those for pure Al Schottky contacts to Si, which do not age with time at these temperatures.
GHz tuning of a planar dye laser with single dispersive element
Authors: Burlamacchi P. , Pratesi R.
Published: February 2003

A new scheme for tuning a planar waveguide dye laser is presented. Because of the high gain produced in the waveguide structure, a high-dispersion slit-grating arrangement can be used as a feedback element of the laser. Output energy of a few tens of mJ, which corresponded to the saturated output of the amplifier, was obtained within a 2-GHz bandwidth. A very stable and repeatable output frequency was observed. The device demonstrates that, as long as the waveguide overcomes gain and refractive index inhomogeneities, a much higher energy output can be expected from scaled-up devices.
On the role of copper in the darkening of silver-halide photochromic glass
Authors: Marquardt Charles L.
Published: February 2003

A photoinduced ESR signal has been detected in silver-halide photochromic glasses. It is shown to arise from Cu++ ions distributed among distorted cation sites in the silver-halide phase. Correlation with optical absorption data suggests that the photoinduced Cu++ may be directly responsible for a significant fraction of the photochromic darkening.
Electroluminescence in Br-, Cl-, and Zn-implanted CuInSe2 p-n junction diodes
Authors: Yu Phil Won , Park Y. S. , Grant J. T.
Published: February 2003

p-n junction diodes have been prepared by implanting Br, Cl and Zn into p-type CuInSe2. The forward current-voltage characteristics can be expressed by I=I0[exp (eV/nkT)−1] with the parameter n≃2. Junctions made by implanting Br and Zn show rectification ratios of 2–3×105 : 1 at 1 V. Electroluminescence was observed in the wavelength region 1.3–1.4 μ with internal quantum efficiency of 20% at 77 °K and 0.1% at room temperature.
Coloration in a WO3 film
Authors: Hajimoto Y. , Hara T.
Published: February 2003

The electrical coloration in WO3 films in practical fabrication originates at the interface between WO3 and CaF2 and migrates towards the cathode. The rate of migration is higher than 1.4×10−9 cm2/V sec.
Oxygen distribution in sputtered Nb-Ge films
Authors: Gavaler J. R. , Miller J. W. , Appleton B. R.
Published: February 2003

A quantiative determination of the distribution of oxygen in a high-Tc (22 K) Nb-Ge film has been made using a nuclear backscattering method. The Nb/Ge ratios as a function of depth have also been determined. An apparent correlation between oxygen concentration and Nb/Ge ratio is observed.
Low-level periodic pulsed energy measurements with an electrically calibrated pyroelectric detector
Authors: Geist Jon , Dewey Harry J. , Lind Michael A.
Published: February 2003

The use of an electrically calibrated pyroelectric detector for accurately measuring periodically pulsed (∼3-ns duration) energy with an average power level in the microwatt to milliwatt range was investigated. Sources of error especially important in this application were the pyroelectric’s acoustic response, its linearity, and possible deterioration of its gold black coating. The detector had a thin polymer film that isolated the radiation receiver from the pyroelectric material. This film temporally resolved the pyroelectric response from the piezoelectric response to the acoustic energy that is associated with the absorption of an impulse of energy. Thus it was demonstrated that the acoustic response was not a serious source of error. The film also reduced the requirement of linearity on the on the pyroelectric transducer by about 5 orders of magnitude from the conditions of a bare transducer. It is concluded that periodic pulsed energy measurements with 5% uncertainties are readily achievable with the detector described.
Profile studies of hydrogen trapping in metals due to ion damage
Authors: Picraux S. T. , Bo/ttiger J. , Rud N.
Published: February 2003

The retention of hydrogen isotopes in Mo at room temperature after ion implantation damage has been studied by measurements of H depth profiles and total D retained in the near-surface region. Implantations of He, O, Ne, and Bi in a fluence range 3×1014–2×1017/cm2 were followed by 8-keV hydrogen bombardment to fluences of 2×1015–2×1017/cm2. Large enhancements in the amount of hydrogen retained in preimplanted samples over samples without prior implantation have been observed and are interpreted in terms of damage trapping. For a given predamage ion fluence hydrogen retention increases linearly with hydrogen fluence until a saturation level is reached. Increased predamage fluence results in increased saturation level for hydrogen trapping, with average concentrations as high as ∼10 at.% achieved. An ion-mass dependence indicates that the lighter ions, which create fewer primary displacements, are more effective in hydrogen trapping, suggesting a dependence on the damage density in the ion cascades.
New model for boron diffusion in silicon
Authors: Anderson J. R. , Gibbons J. F.
Published: February 2003

A new model for boron diffusion in silicon is proposed in which it is assumed that the dominant diffusing species is a neutral boron-vacancy pair (B−V+). Analysis of the model shows that when CB is not the dominant species, the solution of the diffusion equation for constant surface concentration is a complementary error function. When CB is the dominant species during at least part of the diffusion, the diffusion equation must be solved numerically. It is shown that in this latter case, the variation of positively charged vacancy concentration with Fermi level causes the boron diffusivity to appear to be concentration dependent.
Laser performance of large Nd-pentaphosphate crystals
Authors: Gualtieri J. G. , Aucoin T. R.
Published: February 2003

Laser performance of twinned 90% Nd–10% Y-pentaphosphate (0.9 Nd–0.1 YP5O14) crystals with dimensions typically 4.5×3 mm in diamond-shaped cross-section by 2 mm thick is reported. Power conversion efficiencies of ≈24% and peak power outputs of approximately 240 mW were obtained under optical excitation with a repetitively pulsed argon laser. Samples of 0.75 Nd–0.25 InP5O14, 0.1 Nd–0.9 YP5O14, 0.1 Nd–0.9 CeP5O14, and 0.1 Nd–0.9 GdP5O14 were also lased.
Photoelectrolysis of water in cells with SrTiO3 anodes
Authors: Mavroides J. G. , Kafalas J. A. , Kolesar D. F.
Published: February 2003

The photoelectrolysis of water in cells with SrTiO3 anodes has been confirmed. The maximum external quantum efficiency at zero bias voltage is 10% (at hν=3.8 eV), about an order of magnitude higher than the maximum value obtained with anodes of TiO2, the only other material so far known to catalyze photoelectrolysis. In agreement with the energy-level model proposed previously, the efficiency is increased because the band bending at the anode surface is about 0.2 eV larger for SrTiO3 than for TiO2, as a result of the smaller electron affinity of SrTiO3.
Observation of athermal defect annealing in GaP
Authors: Lang D. V. , Kimerling L. C.
Published: February 2003

Capacitance spectroscopy studies of lattice defects intentionally introduced into GaP diodes by 1-MeV electron irradiation have shown a very large enhancement in the defect annealing rate under conditions of e-h recombination. Six deep levels are observed and all exhibit recombination enhanced annealing. Four of the levels anneal athermally during recombination having the same rate at 100 K as at 300 K. Comparisons of the thermal annealing activation energy and the energy released during hole capture indicate that the observed athermal enhancement is a natural consequence of the wide GaP band gap.
Room-temperature poling and morphology changes in pyroelectric polyvinylidene fluoride
Authors: Southgate P. D.
Published: February 2003

At room temperature and below, a complete poling of polyvinylidene fluoride film can be produced in less than 1 sec by corona charging. Changes in pyroelectric coefficient and infrared spectra which accompany this poling are described. A transformation from α to another form occurs; development of most of the pyroelectric property occurs at an early stage of this transformation.
Mode locking of laser oscillators by injection-locking
Authors: Moses E. I. , Turner J. J. , Tang C. L.
Published: February 2003

The possibility of mode locking of high-powered laser oscillators by injection locking to a weak mode-locked signal from a cw laser is proposed and demonstrated. The experiment was carried out using a flash-lamp–pumped pulsed dye laser injection locked to a mode-locked cw dye laser. Gains on the order of 3×104 and nearly Fourier-transform–limited mode-locked pulses were obtained.
Picosecond uv laser pulses from gas discharges in pure nitrogen at pressures up to 6 atm
Authors: Strohwald H. , Salzmann H.
Published: February 2003

Single picosecond laser pulses in the second positive band of nitrogen are observed from high-pressure gas discharges with traveling-wave excitation. The gas discharge is operated in pure nitrogen and without preionization. The pulse duration decreases from 300 psec at 1 atm to 50 psec at 6 atm.