bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in Au-GaAs Schottky barrier diodes with low neutron fluence
Authors: Borrego J. M. , Gutmann R. J.
Published: February 2003

Guarded Au/n-GaAs Schottky barrier diodes fabricated from epitaxial and bulk material with carrier concentrations of 2.2×1016 and 7.8×1016 cm−3, respectively, were exposed to fast neutron fluences between 3.6×1014 and 2.2×1015 neutron/cm2. The forward I-V and 1-MHz C-V characteristics remained relatively unchanged after irradiation at the lower fluences where carrier compensation is small (reduction in carrier concentration less than 15%). However, the reverse current increased by more than one order of magnitude at room temperature, which is neither a result of surface leakage (prevented by the guarded device structure used), classical generation-recombination current (depletion volume changes are too small), nor thermionic emission (too weak a temperature dependence). This increase in reverse current is attributed to enhanced field emission from traps.
Room-temperature operation of GaInAsP/InP double-heterostructure diode lasers emitting at 1.1 μm
Authors: Hsieh J. J.
Published: February 2003

Double-heterostructure Ga0.12In0.88As0.23P0.77/InP diode lasers emitting at 1.1 μm, with room-temperature pulsed thresholds as low as 2.8 kA/cm2, have been fabricated by liquid-phase epitaxy on melt-grown InP substrates.
Accurate phase-matching in sputtered birefringent Ta2O5Nx waveguides
Authors: Wei J. , Ingrey S. J. , Westwood W. D. , Kos S.
Published: February 2003

Accurate matching of propagating constants (or phase matching) of TE0 and TM0 modes has been demonstrated in birefringent waveguides prepared by reactively sputtering tantalum in O2/N2 mixtures. Exact phase matching occurs at a guide thickness of 3926 Å for films with indices of 1.884 and 1.914 on glass substrates. For a coherence length ⩽1 cm, corresponding to a difference in normalized propagation constants, Δ (β/k), of 3×10−5, the thickness must be within 20 Å of this value and this has been reproducibly obtained after calibration of the deposition rate. Reduction of Δ (β/k) to within 6.3×10−6 has been demonstrated. These techniques can be extended to the fabrication of active polarization converters.
Electro-optic channel waveguide modulator for multimode fibers
Authors: Nelson A. R. , McMahon D. H. , Gravel R. L.
Published: February 2003

A multimode electro-optic modulator has been constructed and demonstrated using commercially available multimode fibers. Modulation occurs by the controlled channeling of light under metal electrodes. Significant modulation depth can be obtained for small applied voltages (50% with 14 Vrms) and the ultimate bandwidth is over 600 MHz. Since the device operates on the principle of total internal reflection, performance is independent of wavelength, and precise tolerances are not required for construction. As opposed to single-mode devices, high-efficiency fiber-to-film coupling is readily accomplished.
Optical levitation in high vacuum
Authors: Ashkin A. , Dziedzic J. M.
Published: February 2003

Optical levitation of highly transparent particles has been observed in the high-vacuum regime where viscous damping and thermal conductivity are small, the particle is cooled only by thermal radiation, and radiometric forces are negligible. The effects of an impulse and adiabatic manipulation on the dynamics of a sphere were studied from atmospheric pressure down to ∼10−6 Torr. The calculated time for an oscillating particle to decay to half-amplitude due to the intrinsic optical damping at zero pressure is ∼0.7 years.
Raman band contours for water vapor as a function of temperature
Authors: Bribes J. L. , Gaufrès R. , Monan M. , Lapp M. , Penney C. M.
Published: February 2003

A simplified method of calculation of the contour of a totally polarized Raman band for an asymmetric top molecule in the gaseous state has been applied to produce the first accurate band-shape calculation for the ν1 band of the water molecule. The good fits between computed and experimental contours from approximately 150 to 350 °C lay the foundation for temperature determination for water vapor from measurements of the Raman band profile and for density measurements independent of the temperature.
Nonlinear dynamic theory for photorefractive phase hologram formation
Authors: Kim Dae M. , Shah Rajiv R. , Rabson T. A. , Tittel F. K.
Published: February 2003

A nonlinear dynamic theory is developed for the formation of photorefractive volume phase holograms. A feedback mechanism existing between the photogenerated field and free-electron density, treated explicitly yields the growth and saturation of the space-charge field in a time scale characterized by the coupling strength between them. The expression for the field reduces in the short time limit to previous theories and approaches in the long time limit the internal or photovoltaic field. Additionally, the phase of the space-charge field is shown to be time dependent.
Uniaxial stress effects on double injection diodes
Authors: Hayashi T. , Iida S.
Published: February 2003

Uniaxial stress effects on the current-voltage characteristics of Si and Ge double injection diodes are described and discussed. The threshold and the minimum voltages were decreased and the current flowing in the diode was increased with stress. These variations can qualitatively be explained by the change of mobility of the carrier and the capture cross section, and by the stress-induced deep levels.
Superconducting weak-link current-phase relations
Authors: Jackel L. D. , Warlaumont J. M. , Clark T. D. , Brown J. C. , Buhrman R. A. , Levinsen M. T.
Published: February 2003

Direct measurements have been made of the current-phase relation (CPR) of photolithographic tin microbridges, scribed indium microbridges, proximity bridges, and point contacts. Hysteretic current-phase relations have been observed in uniform-thickness tin microbridges, while proximity bridges have sinusoidal or nearly sinusoidal current-phase relations.
Microfabrication of circuits for magnetic bubbles of diameter 1 μm and 2 μm
Authors: Watts R. K. , Darley H. M. , Kruger J. B. , Blocker T. G. , Guterman D. C. , Carlo J. T. , Bullock D. C. , Shaikh M. S.
Published: February 2003

We describe microfabrication techniques for Permalloy circuits for magnetic bubbles of diameter 1 μm and 2 μm. Patterns are defined by electron beam on an x-ray mask. X-ray lithography and ion milling are employed to replicate the pattern in Permalloy.
Deep trap measurement on S+-implanted layers in GaAs
Authors: Yokoyama N. , Ohkawa S. , Sakurai T. , Furuya T. , Ishikawa H.
Published: February 2003

GaAs substrates were implanted with sulfur at 100, 200, 300 °C, and at room temperature and annealed at 800 °C with SiO2 or Si3N4 protective layers. The density and activation energy of deep traps in the implanted layers were determined from transient capacitance measurements. It is found that implantation at 200 °C and annealing with a Si3N4 film as a protective layer yields the lowest trap density in the implanted layer.
Grating acoustic scanners
Authors: Ro/nnekleiv A. , Souquet J. , Shaw H. J.
Published: February 2003

A simple acoustic scanning device has been devised in which a chirped SAW beam is converted into a focused scanning bulk wave beam by coherent scattering from a grating of parallel grooves. The device can operate in both transmitting and receiving modes, and is applicable to the acoustic imaging of objects in real time.
Application of granular semiconductors to photothermal conversion of solar energy
Authors: Gittleman J. I.
Published: February 2003

A novel selective solar absorber, consisting of a dispersion of semiconductor grains in a low-dielectric-constant insulator is proposed. Calculations based on Maxwell-Garnett theory show that because of its lower reflectivity for λ<1.5 μm this material is about 60% more efficient than silicon in converting solar energy to heat. Reflectivity measurements for Ge-Al2O3 films on aluminum agree with the predictions of the Maxwell-Garnett theory. The problems associated with the reduction to practice are discussed.
Exciton-enhanced conductivity and photoresistivity in tin oxide–dye films
Authors: Seykora E. J.
Published: February 2003

An enhancement of conductivity was observed in an n-type tin oxide semiconductor when coated with a highly polarizable insulating dye. The enhanced conductivity is thought to be a result of conduction electron–exciton interactions. The relationship between the observed photoresistivity and the excited states of the dye molecules is discussed.
Thin-film conducting microgrids as transparent heat mirrors
Authors: Fan John C. C. , Bachner Frank J. , Murphy R. A.
Published: February 2003

A new type of transparent heat mirror for solar-energy applications has been fabricated by chemically etching a Sn-doped In2O3 film to form a transparent conducting microgrid. For square openings 2.5 μm on a side, separated by lines 0.6 μm wide, the solar transmission increases from 0.8 for the original continuous film to 0.9 for the microgrid. Although 65% of the area of the film is removed by etching, the infrared reflectivity decreases by only 9%, from 0.91 to 0.83. A smaller decrease in the infrared reflectivity may be possible if materials with higher optical conductivity are used.
Time-resolved pump depletion in n-InSb Raman spin-flip laser
Authors: Cantrell C. D. , Figueira J. F. , Scott J. F. , Scully Marlan O.
Published: February 2003

Analysis of the transient depletion of a 10.6-μm laser beam in n-InSb at 2 K observed by Figueira, Cantrell, Rink, and Forman shows that the observed depletion is not due to causes such as lattice heating, depletion by other nonlinear processes, or optical damage. Simple estimates are presented which show that a 10.6-μm laser pulse of the intensity and duration of that used by Figueira et al. will heat the conduction electrons very strongly, leading to a transient increase in carrier concentration and conductivity, and a corresponding increase in optical absorption.
Boron fluoride and aluminum fluoride infrared lasers from quasicontinuous supersonic mixing flames
Authors: Rice W. W. , Beattie W. H. , Oldenborg R. C. , Johnson S. E. , Scott P. B.
Published: February 2003

Laser action has been observed from the chemical reaction of fluorine injected into supersonic flows of boron and aluminum atoms. The laser output in the 12.8–20-μm region (AlF) is temporally different from that in the 6.1–13-μm region (BF), but both have pulse durations 103–104 longer than any of the previously reported metal atom oxidation lasers.
Investigation of the training problem of superconducting magnets
Authors: Schmidt Curt
Published: February 2003

The behavior of superconducting NbTi wires under dynamic mechanical stress was investigated. Instabilities on the stress-strain curve (serrated yielding) were found connected with local transition into the normal state. With applied field and transport current, NbTi conductors with and without copper matrix showed a training behavior. This means that the normal transitions occurred at successively higher stress levels. Mechanisms proposed so far, such as serrated yielding of NbTi or deformation of the copper matrix in compound conductors, do not seem to explain the training of superconducting magnets.
Domain wall image contrast in the SEM
Authors: Joy D. C. , Leamy H. J. , Ferris S. D. , Yakowitz H. , Newbury D. E.
Published: February 2003

Contrast from domain walls in materials with cubic magnetic anisotropy has been observed in scanning electron microscope (SEM) images. This contrast, which is visible in both the backscattered and absorbed current images, with normal electron beam incidence arises from the interaction of the convergent incident electron beam with the domains on either side of the wall.
Effect of light illumination on CdS-LiNbO3 convolver and relation to the photoconductivity spectrum
Authors: Ueda Z. , Shirafuji J. , Inuishi Y.
Published: February 2003

The effect of light illumination on CdS-LiNbO3 convolvers at 77 K and room temperature is investigated. The spectral response of the convolution output is closely connected with the photoconductivity spectrum, and at 77 K three exciton lines are clearly observed in the spectrum of the convolution output. Whether the convolution output is enhanced or quenched under illumination depends on the magnitude of the surface barrier of the semiconductor. The results are qualitatively explained on the basis of the increase in carrier density near the semiconductor surface by the light illumination.
Surface acoustic wave reflective dot array (RDA)
Authors: Solie Leland P.
Published: February 2003

A new type of reflective array device is described in which the array of reflecting grooves is replaced by an array of reflecting metallic dots. This reflective dot array or RDA has the principal advantage of being part of the same mask and metalization as the transducers allowing single-step fabrication. A bandpass filter operating at 213 MHz with a bandwidth of 6 MHz, which was fabricated using this technique, has a passband-to-sidelobe ratio of nearly 60 dB.
Parametric study of the current induced in a CO2 laser plasma
Authors: Drouet M. G. , Pépin H.
Published: February 2003

The current generated during the interaction of a focused 10.6-μm CO2 nanosecond laser pulse with a copper target was measured as a function of laser power—up to 2.5 GW—and of the background nitrogen pressure from 10−5 to 103 Torr. Current distribution at the target was measured. The results show a resonance effect at 10−2 Torr with a total current flow of 250 kA.
Vacancies and vacancy clusters in shock-loaded molybdenum: Direct observations by transmission electron and field-ion microscopy
Authors: Murr L. E. , Inal O. T. , Morales A. A.
Published: February 2003

A novel experimental sandwich arrangement of molybdenum thin sheets and wires was shock-loaded at a pressure of 150 kbar (for 2 μsec), and thin foils and emission end forms prepared from these samples were simultaneously examined by transmission electron and field-ion microscopy, respectively. Dislocation loop densitis were observed to be 5×109 cm−3 in the annealed foil samples as compared with 4×1014 cm−3 in the shock-loaded foil samples, and 75% of the loop types analyzed were vacancy. The direct measurement of vacancy density in the field-ion microscope revealed twice as many vacancies (including aggregates) in the shock-loaded wires as compared with the annealed unshocked wires.
Nd-glass thin-film waveguide: An active medium for Nd thin-film laser
Authors: Chen Bor-Uei , Tang C. L.
Published: February 2003

We report the optical properties, fluorescence lifetime, and method of fabrication of very low-loss and high-optical-quality Nd-glass thin films. Substantial optical gain due to stimulated emission in such thin films is obtained.
Direct observation of the Riedel singularity in a superconducting point contact
Authors: Vernet G. , Adde R.
Published: February 2003

An heterodyne detection of the Josephson current in the gap region is performed using the oscillator-mixer mode of operation in a superconducting point contact. The direct observation of the Riedel peak in a Josephson device is realized. The measured peak height (∼3.5) in superconducting point contacts is of the same order of magnitude as for oxide barrier tunnel junctions. Consequently, strong similarities exist in the physical processes which occur in these two types of junctions and pair tunneling is believed to be a dominant mechanism in a point contact with Josephson behavior.
Production of solar cells by recoil implantation
Authors: Christensen Ove , Bay Helge L.
Published: February 2003

Photodiodes have been produced by recoil implantation of Al and Ga into Si, using inert-gas-ion bombardment. Yields as large as 40 implanted Ga atoms per incoming Xe ion have been observed. The diodes were characterized by optical-window thicknesses from 0.14 to ∼1 μm.
Photoinduced electrochromic effect and its applications to displays
Authors: Pole R. V. , Sincerbox G. T. , Shattuck M. D.
Published: February 2003

A liquid solution of an organic donor of the pyrazoline class in a halogenated solvent placed between two transparent electrodes shows blue-color-generating electrochromism whose coloring intensity can be controlled by external illumination. The effect seems to be applicable to optically addressable direct-view passive displays.
Continuous room-temperature operation of GaAs-AlxGa1−xAs double-heterostructure lasers prepared by molecular-beam epitaxy
Authors: Cho A. Y. , Dixon R. W. , Casey H. C. , Hartman R. L.
Published: February 2003

The continuous (cw) operation at temperatures as high as 100 °C of stripe-geometry GaAs-AlxGa1−xAs double-heterostructure lasers fabricated by molecular-beam epitaxial (MBE) techniques has been achieved. Improved MBE laser performance was the result of the extensive efforts to eliminate hydrocarbon and water vapor from the growth apparatus. For 12-μm-wide stripe-geometry lasers with 380-μm-long cavities, the cw threshold currents varied between 163 and 297 mA at room temperature.
Photovoltaic effect in MIS diodes or Schottky diodes with an interfacial layer
Authors: Singh R. , Shewchun J.
Published: February 2003

Recent reports in the literature indicate that the introduction of an interfacial oxide layer in a Schottky barrier can increase greatly the photovolatic conversion efficiency of such devices. We propose an explanation for the operation of such solar cells based on the concept that they are minority-carrier nonequilibrium MIS tunnel diodes.
Direct nuclear pumping of a Ne-N2 laser
Authors: DeYoung R. J. , Wells W. E. , Miley G. H. , Verdeyen J. T.
Published: February 2003

Direct nuclear pumping of a Ne-N2 laser has been achieved with simultaneous output at two wavelengths (8629 and 9393 Å) in atomic nitrogen. Pumping was achieved through bombardment of the gas by MeV ions generated when neutrons from a TRIGA reactor interact with a boron-10 coating on the inner wall of the laser cell. Pressure, concentration, threshold, and other parameters are presented.
Information storage in piezoelectric powders
Authors: Sawatzky G. A. , Huizinga S.
Published: February 2003

In this paper we show that a large amount of information can be stored in a sample of piezoelectric powders. The technique used to write and read the information is based on the principle of phonon echos. It is demonstrated that the frequency can serve as an address of a memory and that a word can be written into each address by selecting an appropriate writing pulse sequence. It is also shown that the information contained in one address can be read out quickly and nondestructively.
Excitation of polyatomic molecules in vapor phase by noble-gas metastable atoms
Authors: Sakurai T. , Littlewood I. M. , Webb C. E.
Published: February 2003

The fluorescence spectra originating from the first excited singlet states of the vapor phase dyes perylene and POPOP have been observed in a flowing noble-gas afterglow. Excitation has been shown to follow energy transfer from noble-gas metastable atoms to the dye molecule.
Spatially resolved measurements of plasma instabilities using a heavy ion beam probe
Authors: Glowienka J. C. , Jennings W. C. , Hickok R. L.
Published: February 2003

A heavy ion beam probe has been used to obtain spatially resolved instability measurements in an energetic magnetically confined plasma. The amplitude and phase of both density and space potential fluctuations associated with a coherent 70-kHz oscillation have been measured in a hollow cathode discharge. The measurements are made simultaneously from the same point in the plasma, are continuous in time, and have a spatial resolution element of <5 mm.
Nd:YAG single-crystal fiber laser: Room-temperature cw operation using a single LED as an end pump
Authors: Stone J. , Burrus C. A. , Dentai A. G. , Miller B. I.
Published: February 2003

cw laser action has been obtained using as-grown single-crystal Nd:YAG fibers end-pumped by a single high-radiance LED. The fibers were 0.5 cm long and 80 μm in diameter, and the diameter of the LED luminous area was 85 μm. The lowest cw laser threshold was observed at a diode drive current of 45 mA.
Pressure effects on metal oxide varistors
Authors: Wong J. , Bundy F. P.
Published: February 2003

Preliminary results on the strong dependence of current-voltage characteristics of ZnO-based metal oxide varistors on pressure up to ∼5 kbar (nominal) are reported. This letter perhaps constitutes the first pressure study on electronic ceramics.
Energy dependence of the low-energy electronic stopping power
Authors: Brice David K.
Published: February 2003

The correct prediction of the electronic stopping power is important in establishing the basis for the technique of ion bombardment of neutron damage. Experimental measurements of the stopping power and the depth distribution of damage deposition by heavy atomic projectiles incident on matter have shown that the velocity proportional electronic stopping power formulas of Lindhard and Firsov are not valid for projectile velocities in the range from 2v0 up to v1, where v0 is the Bohr velocity and v1 is Lindhard’s proposed upper limit for the validity of these formulas. This letter points out that a previously published modification of the Firsov theory predicts a strong superlinear dependence of the stopping power on velocity in this velocity region due to effects which arise when the incident projectile velocity is comparable with that of the atomic electrons. Apart from a scale factor along the velocity axis, which must be determined from experimental measurement, the modified theory correctly predicts the energy dependence of the low-energy electronic stopping power. Values of the scale factor for a large collection of projectile-target combinations indicate that for most projectile-target combinations the velocity-proportional region of the electronic stopping power does not extend above v0.
Correlation between the thermal stability and activation energy of crystallization in metallic glasses
Authors: Chen H. S.
Published: February 2003

The origin of a large spread in the activation energy of crystallization, ΔE, in metallic glasses is explained based on a structural relaxation model. The calculated ΔE from the available thermal and viscosity data is in fair agreement with the experimental results. It is the structural relaxation which leads to high ΔE (⩾100 kcal/mole) for stable glasses. It is also suggested that the structural relaxation is the rate-controlling factor during the crystallization of the unstable glasses. Thus ΔE for unstable glasses is low (ΔE⩽20 kcal/mole), and is expected to be lower for amorphous metals prepared by low-temperature deposition than for the corresponding melt-quenched metallic glasses.
Homogeneous or inhomogeneous line broadening in a semiconductor laser: Observations on In1−xGaxP1−zAsz double heterojunctions in an external grating cavity
Authors: Wright P. D. , Coleman J. J. , Holonyak N. , Ludowise M. J. , Stillman G. E.
Published: February 2003

In1−xGaxP1−zAsz double heterojunctions (77 °K, yellow) are shown to exhibit either (or both) homogeneous or inhomogeneous line broadening when operated as lasers in an external grating cavity. Just above threshold, inhomogeneous line broadening is observed over much of the recombination spectrum. Well above threshold (large gain), homogeneous line broadening is observed when the grating is tuned onto the cavity modes in the region of line center.
Orientation dependence of lattice strain in silicon epitaxial wafers
Authors: Mihara Minoru , Hara Tohru , Arai Masayuki , Nakajima Masato , Nakamura Suguru
Published: February 2003

Lattice strain due to boron in silicon epitaxial wafers has been measured by the x-ray double-crystal technique. It is found that the lattice strain depends on the crystal orientation and that the strain for (100) is about 1.3 times larger than that for (111). The results for (111) lead to a lattice contraction coefficient for boron β=8×10−24 cm3/atom, which is 1.5–4 times larger than previous values obtained with diffused (111) wafers.
Leaky wave room-temperature double heterostructure GaAs:GaAlAs diode laser
Authors: Scifres D. R. , Streifer W. , Burnham R. D.
Published: February 2003

Operation of a new cleaved facet room-temperature double heterostructure GaAs:GaAlAs laser utilizing leaky wave coupling through the substrate is reported. The coupling mechanism is analogous to that of prism coupling from a waveguide, but no external components are used. The laser produces a highly collimated output beam with approximately 2°×8° divergence. The peak pulsed beam power at 2 times threshold is 1.5 W from one end with approximately one-third of this power in the collimated beam. The total external differential quantum efficiency is on the order of 35%. These desirable characteristics are obtained at the expense of threshold current increases of approximately 30%.
Effects of stresses, induced by thermal contraction of a bronze matrix, on the superconducting properties of Nb3Sn wires
Authors: Luhman Thomas , Suenaga M.
Published: February 2003

The superconducting critical temperature Tc and high-magnetic-field critical-current densities Jc have been measured on bronze-processed Nb3Sn single-core wires prior to and after removing the bronze cladding. Both Tc and Jc, at high magnetic fields, are increased after removal of the cladding. Tc measurements on a series of wires with various core-to-matrix ratios R show that the depression in Tc increases as R decreases. The results are interpreted in terms of a stress imposed on the Nb3Sn layer by the thermal contraction of the outer bronze cladding. Results point to the possibility of a martensitic phase transformation occurring in the bronze-clad Nb3Sn wires.
Visible interference effects in silicon caused by high-current–high-dose implantation
Authors: Seidel T. E. , Pasteur G. A. , Tsai J. C. C.
Published: February 2003

Silicon samples with visible color bands have been produced by high beam currents and have been studied using optical reflectivity, Rutherford backscattering (channeling), and transmission electron microscopy. Backscattering shows crystalline or near-crystalline layers at the surface, buried amorphous layers centered at the damage range, and a deeper damage peak. Complex interference spectra are successfully analyzed for two sets of fringes: a visible set primarily associated with the crystalline layer of index of refraction nx at the surface and an infrared set primarily associated with the buried amorphous layer (na≳nx). Interband transitions in the ultraviolet confirm the existence of crystalline layers at the surface. The deeper damage peak is composed of small dislocations as shown by electron microscopy.
LiNbO3 electro-optic modulator and switch
Authors: Gfeller F. R.
Published: February 2003

We demonstrate an experimental electro-optical modulator/switch based on the principle of coupled guided waves with adjustable coupling gap and interaction length. The maximum extinction ratio observed was −20 dB.
Efficient ir image up-conversion in two-photon resonantly pumped Cs vapor
Authors: Stappaerts E. A. , Harris S. E. , Young J. F.
Published: February 2003

Resonant two-photon pumping in the Cs 6s2S-7s2S transition has been used for 2.9 μm to 4550 Å image up-conversion. A power conversion efficiency of 20% with 1000 resolvable spots was achieved using a pump power of 8 kW. The pumping laser, Nd : lanthanum berylate, has a natural two-photon coincidence with the Cs 6s2S-7s2S transition.
Measurement of the photoconductivity using the acoustoelectric current of the surface wave
Authors: Yamamoto Keiichi , Yamazoe Yoshimitsu , Kameyama Shuichi , Abe Kenji
Published: February 2003

The photoconductivity of CdS single crystals was measured by using the acoustic surface wave. At 130 K, we observed the peaks at 474, 486, 494 (P1), and 505 (P3) μm. The peaks at 474 and 486 μm are due to the exciton transition. P1 and P3 are due to the sulphur vacancy. The temperature shift of the band edge is estimated to be −3.7×10−4 eV/deg from P1 and −3.5×10−4 eV/deg from P3.
Reducing grain-boundary effects in polycrystalline silicon solar cells
Authors: Chu T. L.
Published: February 2003

Solar-cell structures were prepared by depositing successively p- and n+-type silicon layers on low-resistivity p-type polycrystalline silicon substrates. The characteristics of the solar cells are limited predominately by the grain boundaries in the deposited p layer. The effects of grain boundaries can be reduced by increasing the dopant concentration in the p layer, and solar cells of lower series resistance and higher conversion efficiency have been obtained.
A novel inorganic photoresist utilizing Ag photodoping in Se-Ge glass films
Authors: Yoshikawa Akira , Ochi Osamu , Nagai Haruo , Mizushima Yoshihiko
Published: February 2003

By ’’photodoping’’ with silver, chalcogenide glasses become almost insoluble in alkaline solutions. This letter examines the applicability of this effect to silicon microfabrication technology. Suitable processing techniques and exposure characteristics are investigated. It is shown that the (Ag) -Se-Ge glass system can be used as a negative-type photoresist; fine pattern photoetching of less than 1 μm line width in SiO2 is easily achieved. This inorganic photoresist has some advantages over the conventional polymer-type photoresists in resolution, etch resistance to acid solutions, and process reproducibility.
Low-frequency current pulses in a semiinsulating GaAs device
Authors: Mimura T. , Suzuki H. , Ohkawa S. , Ishikawa H.
Published: February 2003

Coherent low-frequency current pulses (3×10−3–2×10−2 Hz at room temperature) have been observed in semiinsulating (SI) GaAs with an epitaxial n-GaAs film (n) as a cathode and an evaporated metal as an anode. By measuring the potential drop across the n-SI junction, very high electric fields have been found near the junction. The periodic creation and annihilation of a space-charge barrier due to deep-lying electron traps localized at the n-SI junction qualitatively explains the prominent features of the phenomenon.
Room-temperature operation of GaAs Bragg-mirror lasers
Authors: Ng W. , Yen H. W. , Katzir A. , Samid I. , Yariv A.
Published: February 2003

Room-temperature operation of GaAs distributed Bragg reflector lasers is reported. The diodes are fabricated from conventional double heterostructures involving only a single step of liquid-phase epitaxy. For gratings with a period of 3700 Å, the diodes lased at 8770 Å, which corresponds to the high-absorption side of the spontaneous emission spectrum. Thresholds as low as 6 kA/cm2 have been realized.
Ultralow-voltage image intensifiers
Authors: Haas W. E. L. , Dir G. A. , Adams J. E. , Gates I. P.
Published: February 2003

A novel reflective image intensifier based on the twisted nematic electro-optic effect is described. The device can be read out with intense actinic radiation without need for an optical blocking layer. Images of very high resolution and excellent tonal range can be obtained at voltage levels as low as 1.6 Vrms.
Laser speckle studies of the electric field suppression of the fluctuations in nematic liquid crystals
Authors: Wiener-Avnear E.
Published: February 2003

The thermal orientational fluctuations of nematic liquid crystals have been studied by analyzing the speckle transmission picture of a coherent laser light. The fluctuations’s suppression on the application of a biasing electric field follows a reciprocal square dependence.
High-order submillimeter mixing in point-contact and Schottky diodes
Authors: Zuidberg B. F. J. , Dymanus A.
Published: February 2003

The 337-μm radiation of an HCN laser has been mixed with the radiation of a 3-mm kylstron in a harmonic mixer employing various types of diodes. Beat notes resulting from different orders of mixing, occurring at frequencies as high as 4.5 THz, could be directly observed on the scope. Gallium arsenide appeared to be the most favorable diode material, whereas the Schottky barrier type produce slightly better results than the conventional GaAs point-contact diodes. The performance of the heterodyne system at 891 GHz is given in terms of sensitivity (NEP) and conversion loss (Lc).
Epoxy-acrylate-coated fused silica fibers with tensile strengths ≳500 ksi (3.5 GN/m2) in 1-km gauge lengths
Authors: Schonhorn H. , Kurkjian C. R. , Jaeger R. E. , Vazirani H. N. , Albarino R. V. , DiMarcello F. V.
Published: February 2003

Laser-drawn epoxy-acrylate-coated fused silica fibers (∼110 μm fiber diameter) have been produced with high and exceptionally uniform strength. When tested in 20-μm lengths, they show a single-moded Weibull distribution, (m∼25), a median tensile strength Sm of 750 ksi (5.25 GN/m2), and a coefficient of variation (ν) of about 0.04. Using the previously justified ’’weakest link’’ model, this predicts Sm∼600 ksi (4.2 GN/m2) for l-km gauge lengths. The measured strength of a 1680-m-long fiber (i.e., the minimum strength found in testing 84 20-m lengths) is 620 ksi (4.35 GN/m2). The capability of drawing kilometer lengths of fibers with strengths of this magnitude and uniformity is extremely important for the production of optical fiber cables.
The probability to avoid optical breakdown at 6943 Å in NaCl
Authors: Kelly P. , Bräunlich P.
Published: February 2003

Computer-simulated ’’one-shot-on-one-site’’ damage events in NaCl at the ruby wavelength are illustrated as deterministic survival curves. Multiphoton-assisted avalanche breakdown is considered for varying laser peak flux densities. For a fixed laser output power level, the effects are calculated for various initial free and trapped carrier concentrations in the presence and absence of multiphoton absorption. The results are in reasonable agreement with recent measurements obtained with LiF and Ar and N2 at intermediate pressures. Experimental observations in NaCl are not presently available.
Phase matching of two-photon resonant 4-wave mixing processes in alkali metal vapors
Authors: Bjorklund G. C. , Bjorkholm J. E. , Liao P. F. , Storz R. H.
Published: February 2003

Many classes of two-photon resonant 4-wave mixing processes in alkali metal vapors are shown to be phase matchable by adjusting the frequencies of the fundamental waves. Essentially perfect phase matching of one such process in Na vapor is demonstrated experimentally and shown for plane waves to be insensitive to variations in spatial distribution of the nonlinear medium.
Gain increase in laser amplifiers by suppression of parasitic oscillations
Authors: Labudde P. , Seka W. , Weber H. P.
Published: February 2003

The influence of fluorescence amplification and parasitic modes on the gain characteristics of a laser amplifier is investigated experimentally for a YAG:Nd rod. Possibilities of suppressing parasitic modes are tested. By cutting small grooves into the cylindrical surface of the rod the gain is shown to be improved by a factor 2.4 with respect to a ground rod.
Preparation of light-focusing plastic fiber by heat-drawing process
Authors: Ohtsuka Yasuji , Hatanaka Yoshimi
Published: February 2003

A light-focusing plastic fiber (LFF) was prepared by the heat-drawing process of the following perform at 106–120 °C under 5–7 g/mm2 stress and draw ratio DR=6–370: preform, a light-focusing plastic rod obtained from the photocopolymerization of methyl methacrylate (MMA) with vinyl benzoate (VB) or vinyl o-chlorobenzoate (VOCB), consisting of linear copolymers. LFF’s of radius rp=0.140 mm and rp=0.071 mm were produced by heat drawing of 4/1 (wt/wt) MMA-VB preform (P series) under DR=121 and of 4/1 (wt/wt) MMA-VOCB preform (Q series) under DR=370, respectively. The refractive-index profile, n (r) ∼r/rp, near the center axis is slightly changed by heat drawing. The internal loss of light transmission of the P-series product is in the range of 4–5 dB/m.
New technique of aligning liquid crystals on surfaces
Authors: Meyerhofer Dietrich
Published: February 2003

A new evaporation procedure for preparing the surfaces of liquid crystal cells is described. It causes the liquid crystal to align uniformly, but with a small tilt bias. This is the optimum configuration for the important field effect display devices. The exact dependence of the orientation on processing parameters and the stability of the surfaces to high temperatures are described.
Infrared radiation tunable from 5.5 to 18.3 μm generated by mixing in AgGaS2
Authors: Seymour R. J. , Zernike F.
Published: February 2003

Infrared radiation tunable from 5.5 to 18.3 μm was generated by difference frequency mixing in AgGaS2. The input sources were two tunable dye lasers, operating in the visible and pumped by a single N2 laser. From the measured phase-matching widths, the absorption of AgGaS2 around 14 μm is calculated.
Collective synchronization of arrays of superconducting thin-film microbridges
Authors: Clark T. D. , Lindelof P. E.
Published: February 2003

Square networks (arrays) of superconducting thin-film ’’Dayem’’ microbridges have been investigated. Due to the uniform properties of our bridges, it was particularly easy to collectively synchronize these networks to a microwave field. Analogue computer calculations indicate that to obtain a free-running single-frequency 2×2 network, the diagonal pairs of junctions must be matched approximately to each other and be different from the other pair. We expect this to be a necessary condition for frequency and phase locking in larger networks, but as yet we have not realized this situation experimentally.
Switching of magnetic bubble states
Authors: Dekker P. , Slonczewski J. C.
Published: February 2003

Pulsed-field procedures for switching magnetic bubbles between four different wall states having unit winding number are proposed. Experiments establish operating margins for the transitions and distinguish the two unichiral states for the first time.
Change in the energy gap caused by acoustic domains in CdS
Authors: Hata Tomonobu , Hara Tsutomu , Hada Toshio
Published: February 2003

This paper shows that tha altered energy gap caused by the acoustic domains in CdS lies between the fundamental optical band gaps e⊥c and e∥c (e: polarization of the incident light; c: c axis of the crystal). The experimental results take into account the errors for both the finite beam diameter and the rotation of polarization of incident light due to scattering.
Nucleation of stacking faults at oxide precipitate-dislocation complexes in silicon
Authors: Tan T. Y. , Wu L. L. , Tice W. K.
Published: February 2003

Nucleation sites of thermal oxidation-induced stacking faults in Czochralski-grown silicon crystals have been studied by transmission electron microscopy. Such sites are commonly found to consist of oxide precipitate-dislocation complexes, which appear as center etch pits in line figures delineating faults in optical observations. Embryonic faults were detected in these complexes. These results are strong evidence that stacking faults in silicon result from dissociation of (1/2) 〈110〉 dislocations on a sessile {111} plane.
Thermally activated trapping in Fe-doped LiNbO3
Authors: Zylbersztejn A.
Published: February 2003

Small polaron formation in LiNbO3 is shown to cause thermally activated electron capture on deep impurities. The activation energy for carrier trapping is calculated by using a simple model, which takes into account ionic relaxation for both the impurity and the lattice. The calculation predicts an activation energy for thermal decay of an excess Fe2+ population which agrees with experiment.
Mechanisms of the plasma spatial filter for high-power lasers
Authors: Max C. E. , Mead W. C. , Thomson J. J.
Published: February 2003

We describe mechanisms operating in the plasma spatial filter. Curvature of the critical density surface of the blow-off plasma causes high and intermediate spatial frequencies on the incoming laser beam to be rejected. In addition, time-dependent plasma motions result in the masking of high spatial frequency information on a time-integrated near-field photograph of the beam. Effects on the spectrum of the reflected laser light are evaluated.
Excimer emission band at 235.5 nm in the XeCl molecule
Authors: Shuker R.
Published: February 2003

Band emission at 235.5 nm is observed in fast discharge in a Xe/Cl2 mixture at low pressure. This emission has the same spectral width as that of the excimer 2Σ+1/2→ 2Σ+1/2 transition at 307 nm. It is suggested that this band is also due to bound-free transitions, but belongs to the spin-orbit split level 2Π state of the ionic XeCl molecule that correlates with Xe+(2P1/2) and Cl−(1S). The molecular energy gap between 2Σ+1/2 and 2Π1/2 is almost equal to the atomic spin-orbit splitting and their potential curves are very similar. This bound-free 2Π1/2→2Σ+1/2 emission may be an excimer laser candidate.
High cw power ultraviolet generation from wall-confined noble gas ion lasers
Authors: Tio Tjiaw Khim , Luo Hann Hua , Lin Shao-Chi
Published: February 2003

cw ultraviolet laser output of up to 16 W from the 3511- and 3638-Å lines of Ar III, 6.7 W from the 3507- and 3564-Å lines of Kr III, and 1.8 W from the 3746- and 3781-Å lines of Xe III have been observed in purely wall-confined noble gas discharges. The current density dependence of laser output from these doubly-ionized species is found to be extremely strong but consistent with our theoretical predictions. The maximum observed output of 16 W from Ar III so far, however, is only limited by rapid optical degradation of the uv cavity mirrors.
Comparison of bubble wall state stability observed in (YSmCa)3(GeFe)5O12 and (YEu)3(GaFe)5O12 garnets
Authors: Brown B. R. , Hsu T.
Published: February 2003

Measurements of S-state stability during translational motion show that bubble wall states in 5–6-μm YSmCaGeFeO films are stable at drive gradients more than double that in YEuGaFeO films. The increased stability is believed to result from greater damping and exchange energy in the YSmCaGe garnet.
Effect of He ion implantation on the domain structure of evaporated single-crystal Ni thin films viewed by Lorentz electron microscopy
Authors: Proto G. R. , Lawless K. R.
Published: February 2003

Large dosages of He ions are shown to produce stripe domains in single-crystal Ni films. This effect is tentatively ascribed to the presence of ion-implantation-induced planar stresses which act through the inverse magnetostriction to oppose the shape anisotropy energy.
Polycrystalline thin-film InP/CdS solar cell
Authors: Bachmann K. J. , Buehler E. , Shay J. L. , Wagner S.
Published: February 2003

We report the preparation of a polycrystalline thin-film InP/CdS solar cell of area 0.52 mm2 having a power conversion efficiency of 2.8% under AM1 conditions. Based on the current-voltage characteristics, we estimate that development of an improved contact to the p-type InP would result in substantially higher efficiencies without any further improvement in the InP/CdS interface.
Continuous, flexible, and high-strength superconducting Nb3Ge and Nd3Sn filaments
Authors: Ahmad I. , Heffernan W. J.
Published: February 2003

We report successful fabrication of continuous, flexible, and high-strength (1600 MN/m2) composite filaments of Nb3Ge (Tc 18 °K) and Nb3Sn, involving chemical vapor deposition of these compounds on Nb-coated high-strength W–1% ThO2 filaments.
Piezoelectric electret transducer for ultrasonic generation and detection up to microwave frequencies
Authors: Alquié C. , Lewiner J. , Friedman C.
Published: February 2003

In this paper we report some observations of ultrasonic generation and detection at frequencies up to 9360 MHz using a piezoelectric electret transducer. The transducers were made with biaxially stretched polyvinylidene fluoride films.
Optical image memory in slow surface states in germanium read out by surface acoustoelectric effect
Authors: Shiosaki T. , Narumiya K. , Kawabata A.
Published: February 2003

An optical image can be stored in the slow surface states of Ge and can be read out by the separated medium acoustoelectric effect with a surface wave on LiNbO3. It is found that the surface is sensitive to an optical pattern with optical power less than 1 μW/mm2 at 368 nm wavelength. The memory time is considerably long due to the ’slow’ property of the surface states on Ge.
Transferred-electron photoemission to 1.4 μm
Authors: Escher J. S. , Sankaran R.
Published: February 2003

We report here reflection- and transmission-mode photoemission out to 1.4 μm from a biased field-assisted p-InGaAsP grown on p-InP photocathode. The quantum yield in transmission is ∼0.1% from 0.9 to 1.4 μm. Dark current due to impact ionization by injected holes in the depletion region is observed.
Anomalous plasma heating by an intense laser beam
Authors: Krishan V. , Krishan S. , Sinha K. P. , Ganguli A.
Published: February 2003

Heating of laser-produced plasmas by an instability is investigated through a nonlinear theory that does not treat the laser as a perturbation. It is found that the peaking of the anomalous absorption occurs only for a certain laser power. Comparison has been made with experiment.
Capless annealing of ion-implanted GaAs
Authors: Immorlica A. A. , Eisen F. H.
Published: February 2003

A method is reported for capless annealing of ion-implanted GaAs which gives electrical activation of Se-implanted wafers nearly identical to that obtained with sputtered silicon nitride caps. State-of-the-art performance has been realized from Schottky-gate FET’s fabricated from this material.
Observation of one- and two-electron transfer from noble-gas atom to highly stripped carbon ions
Authors: Goldhar J. , Mariella R. , Javan A.
Published: February 2003

Experimental study of charge transfer between highly stripped ions of carbon and noble-gas atoms was conducted. One- and two-electron transfer to C+3, C+4, and C+5 was observed. The ions were obtained from plasma generated by a pulsed high-power CO2 laser. 422
cw laser action in the blue-green spectral region from Ag II
Authors: Johnson W. L. , McNeil J. R. , Collins G. J. , Persson K. B.
Published: February 2003

We have observed 18 cw laser transitions in Ne-Ag mixtures spanning the wavelength region from 408.6 to 585.2 nm. The upper laser levels of Ag II are judged to be pumped by a charge-transfer reaction between a ground-state neon ion and a ground-state Ag I atom resulting in simultaneous ionization and excitation of the silver atom. Output characteristics of the Ag II laser transitions as a function of neon pressure and discharge current are presented. The two strongest transitions are 478.8 and 502.7 nm in the blue and green, respectively.
Performance of XeF/KrF lasers pumped by fast discharges
Authors: Wang C. P.
Published: February 2003

The output energy and pulse shape of XeF/KrF lasers pumped by fast discharges were measured at various gas compositions and total pressures. For the KrF laser, the maximum output (1.6 mJ) was obtained in a gas mixture of He:Kr:NF3=100:5:0.2 at a total pressure of 700 Torr. The output energy density was 160 mJ/l, and the electrical efficiency was 0.06%. The peak power was 55 kW. For the XeF laser, the maximum output (10 mJ) was obtained in a gas mixture of He:Xe:NF3=100:4:2 at a total pressure of 500 Torr. The peak output power was 1 MW. The output energy density (660 mJ/l) was a factor of 10 higher, and the efficiency (0.5%) was a factor of 2.5 higher than reported earlier.
Second harmonic generation in a thin AlAs-GaAs multilayer structure with wave propagation in the plane of the layers
Authors: van der Ziel J. P. , Ilegems M.
Published: February 2003

Second harmonic generation was measured from a thin AlAs-GaAs single-crystal multilayer using a laser tunable from 1.9 to 2.2 μm as fundamental. Due to propagation effects in the multilayers, the index mismatch nTM(2ω)−nTE(ω), obtained from the coherence length oscillations, is smaller than for the corresponding alloy.