bluuebunny/crossref_metadata_2025 huggingface dataset:
INFRARED DIFFERENCE-FREQUENCY GENERATION USING A TUNABLE DYE LASER
Authors: Dewey C. F. , Hocker L. O.
Published: February 2004

Intense infrared radiation has been produced in the 3–4μ region by generating the difference frequency between a wavelength-tunable dye laser and a Q-switched ruby laser. Saturation of the conversion of ruby photons to sum-and-difference frequencies was observed on a single pass through a phase-matched LiNbO3 crystal. The system appears to be attractive as a simple, highly efficient, and broadly tunable infrared source.
MOBILE CYLINDRICAL DOMAINS IN EPITAXIAL Ga: YIG FILMS
Authors: Mee J. E. , Pulliam G. R. , Heinz D. M. , Owens J. M. , Besser P. J.
Published: February 2004

The properties of mobile cylindrical ``bubble'' magnetic domains observed in gallium-substituted epitaxial yttrium iron garnet films are discussed. At epitaxial film thickness of 5 μm, cylindrical domain diameters of 8 μm are measured at a bias magnetic field of 19 Oe.
BACKGROUND ENERGY CONTENT OF MODE-LOCKED LASER PULSES
Authors: Dube' George
Published: February 2004

Amplified isolated mode-locked pulses from a Nd: glass laser were measured to have a signal-to-noise ratio greater than 104: 1. It is concluded that less than 5% of the laser's total energy output is emitted in the intervals between the subnanosecond pulses, and that there is no nanosecond shoulder on the leading edges of the subnanosecond pulses.
ENHANCEMENT OF OPTICAL SECOND HARMONIC GENERATION BY UTILIZING THE DISPERSION OF AIR
Authors: Yarborough J. M. , Falk J. , Hitz C. B.
Published: February 2004

The dispersion of air, which causes a phase shift of 27.4°/cm between optical waves at 1.06 and 0.53 μ, has been used to compensate for phase shifts between the fundamental and second harmonic in a two-pass second harmonic generation experiment. Use of this dispersion enables the net phase shift to be adjusted to zero, doubling the effective interaction length of the nonlinear crystal. The extension of this technique to multiple-pass experiments is discussed, and applications to internal harmonic generation are treated.
INVESTIGATION OF A CO2 LASER PULSE AMPLIFIER
Authors: Eckbreth Alan C. , Davis Jack W. , Pinsley Edward A.
Published: February 2004

Theory for the adaptation of a N2–CO2 electric-discharge mixing laser (EDML) for use as an amplifier of 10.6-μ laser pulses is described, and the results of an experimental investigation of an EDML pulse amplifier are reported.
FORWARD GOING FILAMENT IN SPARKS INDUCED BY 10.6-μ LASER RADIATION
Authors: Gravel M. , Robertson W. J. , Alcock A. J. , Büchl K. , Richardson M. C.
Published: February 2004

An investigation of sparks produced in a number of gases by means of a transversely excited atmospheric-pressure (TEA) CO2 laser has revealed the existence of a clearly visible plasma filament which propagates at an almost constant velocity in the same direction as the laser beam.
ION-IMPLANTATION DAMAGE IN THIN METAL FILMS
Authors: Bogardus E. H. , Howard J. K. , Peressini P. , Philbrick J. W.
Published: February 2004

Implantation of Ne+, P+, and As+ (45 and 90 keV, dose = 1 × 1016 cm−2) into thin films of Al, Al–Cu, and Ag produce severe damage that results in more rapid material transport during electrical stress than in unimplanted films. Resistivity ratio measurements, i. e., resistivity at 297 and 4.2 °K, appear to be sensitive indicators of this damage.
LOW-TEMPERATURE DISLOCATION DAMPING IN COPPER
Authors: Fate W. A.
Published: February 2004

Ultrasonic attenuation measurements were used to determine the dislocation damping factor in copper. The data are consistent with a temperature-independent electronic component of order Be≈5×10−7 dyn sec/cm2.
PARAMETER DEPENDENCE OF ACOUSTOELECTRIC AMPLIFICATION IN InSb
Authors: Fleming W. J. , Rowe J. E.
Published: February 2004

On the basis of a hydrodynamical theory of the acoustoelectric interaction (Fleming-Rowe) reported earlier which included electron inertial terms it is found that for sufficiently large electron drift velocities sharp high-gain peaks occur. Furthermore the peak values of gain achieved greatly exceed the maximum gain of the corresponding theory of Steele. Excellent agreement with recently reported experimental measurements of microwave acoustic gain in InSb is obtained. It is also noted that for large applied fields, empirical field factors are required to give agreement with experiment.
TYPE CONVERSION AND p-n JUNCTION FORMATION IN LITHIUM-ION-IMPLANTED ZnSe
Authors: Park Y. S. , Chung C. H.
Published: February 2004

High-conductivity n-type ZnSe implanted with Li ions gives evidence of type conversion when tested by thermal probe measurements. Photovoltaic effect, current rectification, and low-voltage electroluminescence were observed in diodes fabricated from implanted material.
SINTERING OF PrCo5 PERMANENT MAGNETS
Authors: Tsui J. , Strnat K.
Published: February 2004

Permanent magnets were produced by liquid-phase sintering from PrCo5 with a Sm–Co and a Pr–Co alloy as sintering aids. The best values of the energy product achieved with these two additives are 21.1 and 16.6 MG Oe; the highest intrinsic coercive forces of different samples are 14 000 and 9470 Oe, respectively.
THE EFFECT OF THE ION MOTION ON THE RADIO FREQUENCY SPECTRUM OF STORED FREE IONS
Authors: Schuessler Hans A.
Published: February 2004

Sideband resonances have been observed in the rf spectrum of free ions stored in a rf quadrupole trap. It was found that the magnetic resonance signals occur not only at the hfs frequency but also at the hfs frequency plus or minus integral multiples of the macromotion and the Larmor precession frequencies of the ions.
STIMULATED EMISSION FROM Ho3+ AT 2 μm IN HoF3
Authors: Devor D. P. , Soffer B. H. , Robinson M.
Published: February 2004

Efficient laser emission of Ho3+ at 2μ has been obtained from a single crystal of HoF3 at liquid-nitrogen temperatures. This is the first pure, undiluted rare-earth compound laser. Fluorescence and absorption spectra indicated a spontaneous linewidth of 1.5 cm−1 for the laser transition. The fluorescence lifetime at 77°K was 2.6 msec, or 29% of the radiative lifetime as measured in dilution in an isomorphic host. The laser threshold for a 15-mm rod was about 1 J.
LAYER WAVE AMPLIFICATION IN A CdS-FLUID-LiNbO3 STRUCTURE
Authors: Araghi M. N. , Das P.
Published: February 2004

Amplification has been achieved by interaction of drifting electrons in a CdS sample which is piezoelectrically coupled to the acoustic layer waves generated in a CdS-fluid-LiNbO3 structure.
SIMULTANEOUS OPTICAL PARAMETRIC OSCILLATION, SECOND HARMONIC GENERATION, AND DIFFERENCE-FREQUENCY GENERATION
Authors: Yarborough J. M. , Ammann E. O.
Published: February 2004

We report the observation of simultaneous phase matching of three separate nonlinear optical processes. The second harmonic of the signal wavelength of a parametric oscillator was generated and then mixed with the idler wavelength of the oscillator to produce a difference frequency, all in the same nonlinear crystal. We have observed 34% average power conversion from the signal to its second harmonic, which is at a shorter wavelength than the pump.
STRIPE-GEOMETRY DOUBLE HETEROSTRUCTURE JUNCTION LASERS: MODE STRUCTURE AND cw OPERATION ABOVE ROOM TEMPERATURE
Authors: Ripper J. E. , Dyment J. C. , D'Asaro L. A. , Paoli T. L.
Published: February 2004

Double heterostructure GaAs junction lasers have been operated continuously at temperatures up to 355°K by use of the advantageous thermal properties of the stripe-geometry configuration. Spatial and spectral characteristics of the modes of these lasers are reported. For the direction perpendicular to the junction plane, these observations show that the field distributions are more symmetrical, the focusing is stronger, and operation in high-order modes is more easily achieved than in homostructure (diffused) junction lasers. For the direction along the junction plane, no significant differences are found between double heterostructure and homostructure lasers.
OXYGEN K EMISSION SPECTRA OF ICE, SOLID CARBON DIOXIDE, AND SOLID ALCOHOLS
Authors: Koster A. S.
Published: February 2004

A long-wavelength x-ray spectrometer with a sample holder cooled by liquid nitrogen was used to obtained oxygen K spectra from ice, solid CO2, and solid alcohols. The nature of the peaks is discussed.
HOT-PRESSED CdCr2S4: AN EFFICIENT MAGNETO-OPTIC MATERIAL
Authors: Ahrenkiel R. K. , Moser F. , Carnall E. , Martin T. , Pearlman D. , Lyu S. L. , Coburn T. , Lee T. H.
Published: February 2004

The ferromagnetic semiconductor CdCr2S4 has been prepared in the form of hot-pressed polycrystalline samples having high optical transmission and Faraday rotation in the near-ir spectral region. In the region 900–1400 nm, the figure of merit exceeds 60° dB−1 at 4.2 °K and 30° dB−1 at 80 °K. It is thus an efficient and potentially useful magneto-optic material at liquid-nitrogen temperature.
ACCURATE CAPACITANCE CALCULATIONS FOR PN JUNCTIONS CONTAINING TRAPS
Authors: EerNisse E. P.
Published: February 2004

Accurate numerical calculations for the small-signal response of PN junctions containing deep-level carrier traps as a function of frequency and reverse-bias voltage are reported for the first time. Calculations for Au-doped Si PN abrupt and diffused junctions compare favorably to published experimental results if the room-temperature emission rates of Tasch and Sah, which leave the Au center only slightly negatively charged in the depletion region, are used. Inclusion of the electric field dependences of the emission rates improves the agreement between experiment and theory. It is demonstrated that ignoring the trapping of carriers which spill over from the more heavily doped side of an asymmetric junction causes some inaccuracies in the use of results from previously published approximate analyses.
PHONON-INDUCED STRUCTURES IN THE TUNNELING CHARACTERISTICS OF n-TYPE Si-OXIDE-METAL JUNCTIONS
Authors: Tsui D. C. , Dunkleberger L. N.
Published: February 2004

Fine structures in the tunneling characteristics of n-type Si-oxide-metal junctions have been observed at biases approximately equal to the energy of peaks in the Si phonon distribution. We show that these structures cannot arise from phosphorus local-mode phonons. Instead, they reflect Si phonon peaks and can be attributed to emission of Si phonons by tunneling electrons.
CURRENT INSTABILITIES IN n-InP
Authors: Grubin H. L. , Shaw M. P. , Conwell E. M.
Published: February 2004

Theory indicates that the frequent observation of circuit-controlled oscillations in n-InP, rather than transit-time oscillations, may be attributed to low cathode boundary fields and the shape of the velocity-electric field relation. For higher boundary fields, in the NDC region, computer calculations show recycling domains with some differences from GaAs. The incorporation of a large diffusion coefficient altered these results only in a minor way.
MICROSTRUCTURAL EFFECTS ON THE MINORITY-CARRIER DIFFUSION LENGTH IN EPITAXIAL GaAs
Authors: Abrahams M. S. , Buiocchi C. J. , Williams B. F.
Published: February 2004

Homo- and heteroepitaxial layers of GaAs were examined by transmission electron microscopy. The epitaxial layers contained four types of defects. These were intrinsic stacking faults, extrinsic faulted loops, dislocations, and precipitates. It is shown that, of these defects, the ones most responsible for limiting the minority-carrier diffusion length are stacking faults.
MICROMAGNETIC SOLUTIONS FOR BUBBLE DOMAINS
Authors: Lin Y. S. , Tu Y. O.
Published: February 2004

The cylindrically symmetric bubble domain bounded by a one-dimensional 180° Bloch wall is analyzed based on a micromagnetic theory. The magnetization distribution in a wall and the bubble energy are calculated as functions of the plate thickness and material parameters. The energy of a bubble (energy relative to that of a saturated platelet) is found to be small (10−5 erg for orthoferrites) compared to the individual energy (magnetostatic, exchange, and anisotropy) terms. The wall thickness is approximated reasonably well by (A/K)1/2. Bubbles with thicker walls yield lower energy and larger wall mobility but bubble size is not affected. It is concluded that Thiele's results of assuming zero wall thickness are valid since the bubble size is nearly independent of wall thickness.
ACOUSTO-OPTICAL MEASUREMENTS OF ACOUSTIC-WAVE GENERATION IN PIEZOELECTRICS COUPLED TO A GUNN OSCILLATOR
Authors: Ishida A. , Sumi M.
Published: February 2004

The acoustic-wave generation in LiNbO3 coupled to a GaAs Gunn oscillator was studied acousto-optically. Domain propagation along the x axis of LiNbO3 produces a y-propagating S6 wave whose frequency is equal to the Gunn oscillator frequency. The S6 wave causes the deflection and the polarization rotation of light normally incident upon the xy plane. The effect is very attractive for its applications to acousto-optic devices.
n-p JUNCTION PHOTOVOLTAIC DETECTORS IN PbTe PRODUCED BY PROTON BOMBARDMENT
Authors: Donnelly J. P. , Harman T. C. , Foyt A. G.
Published: February 2004

n-p junction photovoltaic detectors in PbTe have been fabricated using proton bombardment to create the n-type layer. At 77°K, zero-bias resistance area products of 300 Ω cm2 were observed for diodes with dimensions as large as 15 mil square. Peak detectivities at 5 μm in reduced background as high as 3.3×1011 cm Hz1/2/W were observed. Diode quantum efficiencies were typically greater than 30% at 5 μm.
CHARGE STORAGE ON SMALL METAL PARTICLES
Authors: Laibowitz R.B. , Stiles P.J.
Published: February 2004

Small metal particles (SMP) have been incorporated into a multilayered metal-insulator-semiconductor structure consisting of thermally oxidized Si, SMP, a second insulator, and a top metal electrode. The SiO2 thickness is kept < 30 Å, permitting tunneling of charge carriers between the Si and the discrete states of the SMP. The charge thus stored on the SMP causes a large, controllable hysteresis in the capacitance-voltage characteristic of the structure which is described in terms of an energy-level model.
BLEUSTEIN-GULYAEV SURFACE WAVE AMPLIFICATION IN CdS
Authors: Maerfeld C. , Gires F. , Tournois P.
Published: February 2004

Experiments on Bleustein-Gulyaev electroacoustic surface wave amplification in CdS are described. Large electronic gains up to 105 dB/cm have been obtained at 85 MHz. Comparisons with the amplification of Rayleigh waves propagating on the other faces of the same crystal show that the Bleustein-Gulyaev electroacoustic surface wave gives higher amplifications and is much less dependent on the mechanical and chemical surface disturbances.
STIMULATED SECOND STOKES SPIN-FLIP RAMAN SCATTERING IN InSb
Authors: Patel C.K.N.
Published: February 2004

We report the first observation of tunable stimulated II Stokes spin-flip Raman scattering by conduction electrons in InSb. The tunability of II Stokes spin-flip Raman laser is twice that of the I Stokes spin-flip Raman laser.
WHITE-LIGHT INTERFERENCE ON TWO CIRCULAR GRATINGS
Authors: Biswas S. C.
Published: February 2004

It has been shown that white-light interference is possible on a pair of circular gratings placed parallel to each other against a broad white-light background. Circular spectral rings are observed when the centers of the gratings lie on the line of sight. The pattern can also be photographed.
OPTICAL PROBING OF SURFACE RAYLEIGH WAVES
Authors: Cambon G. , Rouzeyre M. , Simon G.
Published: February 2004

Data are presented on optical probing of Raleigh surface waves by Brillouin diffraction of light. The apparatus uses a low-cost 3-mW He–Ne laser and is shown to be a simple and convenient tool for acoustic losses and velocity measurements. The minimum acoustic amplitude detectable is 0.1 Å and the phase velocity is measured with an accuracy better than 0.6%. We give a simple explanation of the spatial distribution of the acoustic flux and show that in a 6-μsec quartz delay line, losses due to beam spreading are two times greater than the intrinsic loss. The results obtained with gold-coated surfaces indicate that the acoustic beam spreading is very pronounced and can partially alter some conclusions given in previous communications.
STRONG INFRARED-LIGHT SCATTERING FROM COHERENT SPIN WAVES IN YTTRIUM IRON GARNET
Authors: Hu H. L. , Morgenthaler F. R.
Published: February 2004

We report the first direct observation of strong Bragg-scattered infrared light (1150 nm wavelength) from coherent spin waves (1.5 GHz). The maximum scattered-light intensity is found to be at least five times stronger than that of longitudinal elastic waves of comparable power. The experiments were performed with an axially magnetized, single-crystal YIG bar, with the axis oriented in a {100} plane at an angle of 22.5° from a 〈100〉 axis. The coherent spin waves were generated through efficient space-gradient conversion from longitudinal elastic waves; the latter were excited from a sputtered ZnO transducer. The scattered-light intensity is found to be dependent on the incident-light polarization and the sign of frequency shift (Stokes or anti-Stokes lines) and independent of the direction of the applied magnetic field. Previous theoretical calculations on light scattering from coherent spin waves are critically reviewed and revised. The new result appears to explain adequately not only the present experiments but also observations that previous authors have reported as ``anomalous''.
TRAPPING MODEL FOR InSb THIN FILMS
Authors: Coldren L. A.
Published: February 2004

A deep trapping level related to defects is postulated from drift- and Hall-mobility data taken from thin films of InSb on SiO-coated LiNbO3 substrates.
X-RAY DIFFRACTION FROM PIEZOELECTRICALLY AMPLIFIED SHEAR WAVES IN THE 50-GHz RANGE
Authors: Carlson D. G. , Segmüller A. , Mosekilde E. , Cole H. , Armstrong J. A.
Published: February 2004

X-ray diffraction from piezoelectrically amplified acoustic shear waves in GaAs is reported. The spectrum of amplified acoustic flux is obtained in the microscopic limit, where the electron mean free path is much greater than the acoustic wavelength. The peak acoustic intensity occurs at 50 GHz, which corresponds to the frequency of maximum net gain according to the linear theory. The spectrum of piezoelectrically amplified acoustic waves is observed at frequencies an order of magnitude larger than may be studied by the previously reported Brillouin scattering technique.
MEMORY BEHAVIOR IN A FLOATING-GATE AVALANCHE-INJECTION MOS (FAMOS) STRUCTURE
Authors: Frohman-Bentchkowsky D.
Published: February 2004

A novel charge-storage structure is described. The floating-gate avalanche-injection MOS (FAMOS) structure is shown to exhibit memory behavior in the form of long-term charge storage on the floating conductive gate of an insulated gate field-effect device. Charge is stored in the floating polysilicon gate by avalanche injection of electrons from an underlying p-n junction.
DAMAGE DEPTH DISTRIBUTION OF 15-keV Kr IMPLANTED IN RbCl AS OBTAINED FROM DIFFUSION MEASUREMENTS
Authors: Pronko P. P. , Kelly R.
Published: February 2004

The steady-state trapping model for inert-gas diffusion in alkali halides is used to obtain direct experimental information on the damage depth distribution resulting from 15-keV Kr bombardment of RbCl. The average damage concentration falls to 5% at about 350 Å (in rough agreement with random stopping theory) but does not reach 1% until about 650 Å (suggesting that channeled stopping also plays a role). Beyond 1200 Å the implanted damage merges with the background concentration of traps. The traps are shown to be single vacancies by comparing diffusion and conductivity measurements for pure and doped specimens.
CONTROL OF ACOUSTIC SURFACE WAVES WITH PHOTOCONDUCTIVE CdS FILM
Authors: Auld B.A. , Wilson D.A. , Winslow D.K. , Young E.
Published: February 2004

Optical patterns imaged on photoconductive CdS films have been used to generate, detect, attenuate, and reflect acoustic surface waves on a 100-MHz LiNbO3 delay line. Optically induced acoustic attenuation on the order of 1 dB/wavelength has been measured. A 180° reflection coefficient of approximately −7 dB has been observed from an optical grating, and 90° (right angle) reflect on has also been observed with a different optical grating. A transducer using an optical pattern (rather than evaporated interdigital electrodes) has been constructed with a one-way conversion efficiency of −20 dB.
HILLOCKS AS STRUCTURAL MARKERS FOR ELECTROMIGRATION RATE MEASUREMENTS IN THIN FILMS
Authors: Howard J.K. , Ross R. F.
Published: February 2004

A simple experiment is presented to measure the rate of solute mass transport (electromigration) in dilute alloy thin-film conductors. A structural marker motion method was employed to determine the rate of copper movement (average ion velocity=4.5×10−8 cm/sec) in Al–Cu thin films during electrical stress (4.7×105 A/cm2 at 150 °C ambient temperature).
OBSERVED INTERACTION OF ACOUSTIC AND ELECTRON SURFACE WAVES IN A MAGNETIC FIELD
Authors: Krischer Charles , Bers Abraham
Published: February 2004

We report the experimental observation of resonant coupling and amplification of acoustic surface waves on a piezoelectric with electron surface waves on an adjacent semiconductor in a transverse magnetic field. Room-temperature measurements were made at 30 and 150 MHz on a LiNbO3–GaAs structure, using magnetic fields of up to 144 kG.
INTERFEROMETRIC OBSERVATION OF PLASMA FILAMENTS IN A LASER-PRODUCED SPARK
Authors: Richardson M. C. , Alcock A. J.
Published: February 2004

Subnanosecond interferograms with high spatial resolution have been made of the sparks produced in several gases by the output of a single-mode ruby laser. This has resulted in the observation of a plasma filament having transverse dimensions an order of magnitude less than the diameter of the focal region, propagating toward the laser beam, prior to the main plasma formation. The development of this filament is observed, and its production by a self-focusing mechanism is discussed.
HIGH-RESOLUTION SATURATION SPECTRA OF THE IODINE ISOTOPE I2129 IN THE 633-nm WAVELENGTH REGION
Authors: Knox Joseph D. , Pao Yoh-Han
Published: February 2004

Using a He3–Ne20 laser as a light source and techniques of saturation spectroscopy, the relative positions of 38 separate lines have been resolved in a free spectral range of 650 MHz in the 633-nm wavelength region. The absolute reproducibility of the positions of these lines has also been investigated with the view of use of them as wavelength standards and is found to be of the order of 1 part in 109 or better.
CANCELLATION OF SLIT-WIDTH AND DOPPLER BROADENING EFFECTS IN THE SPECTROSCOPY OF FAST ION BEAMS
Authors: Stoner John O. , Leavitt John A.
Published: February 2004

We use the Doppler shift of light emitted by fast ion beams to cancel the broadening introduced by opening the spectrometer entrance slit. Hence, wide slits are used to increase collected flux with minimal increase in recorded linewidth.
FREQUENCY SHIFT AND SUPPRESSION OF ION-WAVE INSTABILITY BY HIGH-FREQUENCY ELECTRIC FIELD
Authors: Aihara S. , Takamura S.
Published: February 2004

The frequency of an ion wave decreases in an rf electric field. At the same time strong suppression of the ion-wave instability occurs. The frequency shift is explained by the additional pressure which is produced by the spatial modulation of the rf field by the ion wave.
HIGH-INTENSITY TUNABLE InSb SPIN-FLIP RAMAN LASER
Authors: Aggarwal R. L. , Lax B. , Chase C. E. , Pidgeon C. R. , Limbert D. , Brown F.
Published: February 2004

Stimulated spin-flip Raman scattering with output peak power as high as ∼ 1 kW has been obtained from n-type InSb (ne ≃ 2 × 1016 cm−3) pumped with 10.6-μ radiation from a pulsed high-pressure CO2 laser. The output is tunable from 11.2 to 12.8 μ with magnetic fields from 25 to 100 kG. The threshold intensity for stimulated scattering has been measured to be as low as 4 × 104 W/cm2, which is more than one order of magnitude lower than those reported earlier. The high intensity (∼ 1 kW) in the Stokes line excites a second stimulated Stokes line tunable from 12.0 to 14.6 μ with output power of several watts. In addition, a stimulated anti-Stokes line, tunable from 10.0 to 9.0 μ, with output power of ∼ 30 W has been observed.
EXPERIMENTAL DETERMINATION OF THE CROSS SECTION FOR MULTIPHOTON IONIZATION OF NEON NEAR A RESONANCE
Authors: Baravian G. , Benattar R. , Bretagne J. , Callede G. , Godart J. L. , Sultan G.
Published: February 2004

We measure the number of charges produced when a laser beam is focused in neon. Taking into account the configuration of the emitted modes we obtain experimental values for the cross section for multiphoton ionization. By varying the energy of the emitted photons, we can compare our results with a single-mode theory.
EFFECTS OF THERMALLY DIFFUSED IMPURITIES ON PROPAGATION OF ELASTIC SURFACE WAVES ON THE FERROELECTRIC CERAMICS
Authors: Toda K. , Takahashi K. , Okazaki K.
Published: February 2004

It is shown that impurities introduced by thermal diffusion can improve propagation properties of surface waves excited on unpolarized ceramic plates using an interdigital arrangement of electrodes. In BaTiO3 ceramics, CO2O3 reduces the attenuation constant of surface waves to one-half the values obtained with specimens with no added impurities. In the most favorable case, the output voltage due to the surface waves increased by a factor of 3.
EXPERIMENTS ON LIGHT WAVES IN A THIN TAPERED FILM AND A NEW LIGHT-WAVE COUPLER
Authors: Tien P. K. , Martin R. J.
Published: February 2004

We discuss experiments in an asymmetric optical waveguide which is simply a dielectric film deposited on a substrate. The film has a tapered edge. Near this edge and depending on the angle of incidence, a guided light wave in the film may be totally reflected or it can enter into the substrate as radiation modes. In the latter case, the tapered film edge is used here to couple light energy into or out of the film.
SIMULTANEOUS MODE LOCKING AND PULSE COUPLING OF THE CO2 LASER
Authors: Eguchi R. G. , Steier W. H. , Mann M. M. , Lacina W. B.
Published: February 2004

Simultaneous mode locking and pulse coupling of a CO2 laser has been achieved using a single internal GaAs element with electrodes on both the (001) and (110) faces. Coupling of pulses from the laser did not affect the stability of the mode-locked pulse train. Possible application of the technique to pulse-code modulation of the CO2 laser is discussed.
Effects of the Magnitude and Crystallographic Direction of a Thermal Gradient on Droplet Migration in Solids
Authors: Cline H. E. , Anthony T. R.
Published: February 2004

The migration behavior of saturated water inclusions in KCl was determined as a function of both the magnitude and the orientation of an applied thermal gradient. A flattening of the droplet perpendicular to the thermal gradient was observed to intensify with increasing thermal gradient. A nonlinear relation between the droplet migration rate and the applied thermal gradient was attributed to direct and indirect effects of interface kinetics. Below a critical thermal gradient dependent on droplet size, the migration velocity becomes zero. The crystallographic orientation of the thermal gradient had only a small effect on the shapes and velocities of small droplets. In contrast, the orientation of the thermal gradient significantly influenced the behavior of larger droplets, causing some of them to adopt chevronlike shapes.
Filamentary Thermal Breakdown in Thin Dielectrics
Authors: Shousha Abdel Halim M. , Pulfrey David L. , Young Lawrence
Published: February 2004

A model of the breakdown of thin dielectric films is presented in which breakdown can result from thermal effects following a nondestructive electron avalanche. It is proposed that the avalanche leads to the generation of sufficient heat in a narrow channel for the ordinary electrical conductivity of the channel to be raised to a level at which thermal runaway could start, thus leading to destructive breakdown in a narrow region of the dielectric. The effects, on the time required for breakdown to occur, of input power, heat dissipation, and initial temperature rise caused by the avalanche are computed.
Electrical Transport and Photoelectronic Properties of ZnTe:Al Crystals
Authors: Larsen T. L. , Vorotto C. F. , Stevenson D. A.
Published: February 2004

A study of native and impurity defect levels in Al-doped high-resistivity ZnTe is described. Experimental information includes electrical transport, photoluminescence, and photoconductivity measurements. Analysis of this information led to the following defect-level assignments: an acceptor level 0.25 eV from the valence band, attributed to a Zn-vacancy-Al-donor complex; an acceptor level 0.60–0.65 eV from the valence band, assigned to a native defect, possibly the second level of a zinc vacancy; and a donor level 0.1 eV from the conduction band, assigned to the dopant aluminum. These levels are involved in radiative recombination which gives rise to three photoluminescence bands with peaks near 2.11, 2.04, and 1.63 eV at 77 °K, observed in Zn-vapor-annealed ZnTe : Al single crystals.
dc and ac Josephson Effect in Sputtered Nb–NbOx–Pb Junctions
Authors: Schwidtal K.
Published: February 2004

The magnetic field dependence of the maximum dc Josephson current and of the ac Josephson-effect-induced step structure have been measured for sputtered Nb–NbOx–Pb Josephson junctions, and found to be in very good agreement with theoretical predictions; even for junctions made with ``dirty'' Nb thin films. From this agreement it is concluded that the observed anomalies in the I-V characteristics, namely, excess currents for voltages Δ(Pb)<V<Δ(Pb) + Δ(Nb) and a ``knee'' in the I-V curve at voltages just above Δ(Pb) + Δ(Nb), cannot be attributed to nonuniformities in the plane of the junction. It is further shown that these anomalies, especially the ``knee'', can be explained by a proximity-effect model in which the surface of the Nb thin film is assumed to be gapless due to gaseous impurities. The junctions were found to be much more stable with respect to repeated-thermal cycling and storage at room temperature than Pb–PbOx–Pb junctions made under the same conditions.
Two-Stage Epitaxial Growth of GaAs E1 Diodes on Spinel
Authors: Ladany I. , Wang C. C.
Published: February 2004

Heteroepitaxial GaAs films were grown on dielectric substrates, sapphire and spinel, by a two-stage epitaxial process. The nucleation and initial film growth are achieved by a vapor phase-growth technique. Further film growth and p-n junctions were obtained by the liquid-phase epitaxial technique. Mesa diode arrays were successfully fabricated in Te- and Zn- doped grown layers on spinel. The diode I-V and L-V characteristics are similar to those obtained on bulk GaAs and indicate good thermal contact between GaAs and spinel. Electroluminescence peaking near 9000 Å is obtained, the radiation leaving the junction both from the mesa surface and from the opposite side through the spinel. The external quantum efficiency achieved was about 0.1%.
Elastic, Piezoelectric, and Dielectric Constants of Bi12 GeO20
Authors: Slobodnik A. J. , Sethares J. C.
Published: February 2004

In order to resolve conflicting published results concerning the values of the elastic, piezoelectric, and dielectric constants of Bi12GeO20, an exhaustive study of this material has been made. Over 45 samples of material grown by three independent sources were tested. The piezoelectric constant was determined using three different techniques. In addition, the first accurate measurements of the dielectric constant of Bi12GeO20 at microwave frequencies have been made. Recommended values of the material constants are as follows: c11E=1.28×1011 N/m2, c12E=0.305×1011 N/m2, c44E=0.255×1011 N/m2, e14 = 0.99 C/m2, and ε11S=34.2×10−11 F/m.
Photoconductivity in Epitaxial Pb1−xSnxTe
Authors: Logothetis E. M. , Holloway H.
Published: February 2004

Bulklike photoconductivity has been observed in Pb1−xSnxTe (x ≈ 0.17) layers deposited on BaF2. At 77 °K a peak detectivity of 6.6 × 108 at 8.9 μ has been measured for carrier concentrations of about 4 × 1016 cm−3.
Verification of Static Spherical Probe Theory in a Moving High-Pressure Plasma
Authors: Clements R. M. , MacLatchy C. S. , Smy P. R.
Published: February 2004

The static high-pressure spherical probe theories of Su and Lam, Cohen, and Kiel have been experimentally verified in a flame plasma by moving probes through a flame at the flame velocity and thereby minimizing motional effects. The saturation currents and the current-voltage characteristics at negative voltages show good agreement with the calculated values providing that at high probe bias levels a correction is made for the finite residence time of the probe in the plasma. By deliberately introducing a relative velocity between the flame and the probe, the velocity imposed limits of applicability of the probe theory at different voltages were found. For most practical purposes the condition given by Lam that the electric Reynold's number should be < 1 is shown to be an adequate criterion for the use of these theories. The implications of these velocity limitations to the results given by previous workers who have used static high-pressure probe theory in moving plasmas are discussed.
Anomalous resonance of strontium titanate
Authors: Neville R. , Hoeneisen B. , Mead C. A.
Published: February 2004

An anomalous resonance exhibited by perovskite strontium titanate crystals are obtained by cooling the samples with an applied electric field. A plausible mechanism involves a mechanical oscillation with a frequency determined by the domain boundary spacing, which is coupled to the electric field through the piezoelectric strain constant.
Magnetic focusing of a relativistic electron beam: experiment
Authors: Bolduc P. E. , Patterson E. L.
Published: February 2004

A magnetic mirror is used to control and focus a 2.0-MeV 70-kA electron beam. Mirror ratios of 3.7 and 5.9 and magnetic fields of 2.0, 2.5, and 5.0 kG are used. A 500-μ air pressure is used in the drift tube to minimize the beam's electrostatic and magnetic self-forces. The surface-energy deposition in a sample placed at the peak of the 3.7 to 1 bottle is approximately twice as large as that obtained with beam self-focusing without an external field. The fluence and energy as a function of axial position in the region of low-grad Bz agree with the results of adiabatic theory and are found to be independent of magnetic field strength and nearly independent of mirror ratio for the selected ranges. Reproducibility in delivered energy, fluence, and surface-energy deposition is significantly greater than that obtained without an external magnetic field. The induced Bz field due to beam rotation or plasma diamagnetism is approximately 1% of the applied field.
Internal reflection ellipsometry for metal deposits
Authors: Chan E. C. , Marton J. P.
Published: February 2004

A method for determining the optical constants of thick absorbing metal deposits on a homogeneous and isotropic substrate is developed by measuring the ellipsometer parameters ψ and Δ at the substrate-metal interface. The method is advantageous because surface contamination of the metal deposit by the atmosphere is eliminated. It also lends itself to an accurate determination of the thickness and optical constants of oxides formed on the air side of the metal deposit. Results of measurements are compared for gold, platinum, and silver with those obtained from conventional ellipsometry. An example of oxidation of Ni–P deposits is also given. The results demonstrate the validity and versatility of the present technique; apart from being simple and easy to apply, the calculations of refractive indices are exact with no approximation involved.
Time variations in the far-field diffraction patterns of spatial modes from electron-beam-pumped semiconductor lasers
Authors: Garside B. K. , Shewchun J. , Kawasaki B. S.
Published: February 2004

Detailed observations of the far-field radiation patterns from electron-beam-pumped GaAs and CdSe lasers reveal angular deviations of the patterns from the laser axis at angles greater than 25°. Moreover, these angular deviations are observed to decrease monotonically as a function of time during each output pulse. A simple model for the near-field laser modes predicts such angular deviations. Furthermore, the model allows the time-varying angular deviations to be accounted for in terms of a time-varying refractive index difference between the pumped and unpumped regions of the laser cavity. Two major sources of sufficient index variations are identified, viz., heating by the electron beam and index changes related to the presence of gain. The relative magnitudes of the two effects have been determined for GaAs and CdSe. The inherent time dependence of these effects proves adequate to account for the observed ``angular tuning'' of the spatial modes. Spatial variations in the refractive index have consequences other than angular tuning of the far-field modes. In particular, it is found that the diffraction losses associated with the spatial modes are strongly dependent on the refractive index difference. The impact on laser dynamics of the consequent time-varying total cavity loss is discussed.
Investigation of static electron irradiation effects in bulk Si and thin Si films at energies far below threshold
Authors: Norris C. B.
Published: February 2004

This paper investigates the defect production in Si reported to occur at electron irradiation energies far below the theoretically predicted 170-keV bulk-damage threshold. In contrast to published results, our experiments show no permanent resistance changes in bulk samples at fluences as high as 2×1018 20-keV e/cm2 (78 K). Furthermore, fundamental damage studies using EPR techniques and optical spectroscopy confirm that fewer than 10−4−10−5 atomic displacements occur per 20-keV electron. These results disagree with previous studies of irradiation-induced resistance changes in bulk samples and epitaxial films from which it was indirectly determined that subthreshold atomic displacements appear following ionization of a Si K-shell electron. However, we do find large resistance decreases in p-type Si/spinel films at fluences ≳1015 20-keV e/cm2 (300 K) that appear similar to anomalous results in the literature. But the energy and fluence dependences of the resistance change in our experiments are correctly predicted by theory for an irradiation-induced charge accumulation layer localized within <500 Å of the irradiated Si surface. The results do not indicate the presence of a bulk-damage mechanism. The K-shell hypothesis is clearly ruled out since the resistance effect remains at energies well below the K-shell ionization potential. We do not find a corresponding irradiation effect in n-type Si/spinel films which is consistent with the fact that nearly all the previously reported subthreshold irradiation effects have appeared in p-type Si. Our results clarify some puzzling aspects of previously reported low-energy electron irradiation effects in Si and also indicate that the unambiguous determination of defect introduction or existing defect modification by subthreshold irradiation of semiconductors requires fundamental techniques that can be rendered immune to surface phenomena.
Scanning electron microscopy and cathodoluminescence of ZnSex Te1 − x
p-n junctions
Authors: Aven M. , Devine J. Z. , Bolon R. B. , Ludwig G. W.
Published: February 2004

The structure of ZnSex Te1−xp-n junction diodes has been examined under cathode-ray excitation. The cathodoluminescence efficiency of p-type ZnSex Te1−x drops by a factor of 102−103 between 77 and 300 °K, whereas that of n-type material stays approximately constant in the same temperature range. Junction profiles obtained by cathodoluminescence, cathodoconductivity, and secondary electron emission indicate that the radiative recombinations occur on the p-type side of the diodes. The large drop in the diode efficiency between 77 and 300 °K is thus attributable to the decrease of the radiative recombination efficiency of p-type ZnSex Te1−x.
Laser-scanning photoemission measurements of the silicon-silicon dioxide interface
Authors: Williams R. , Woods M. H.
Published: February 2004

We have used the uv line of the He–Cd laser at 3250 Å to excite photoemission of electrons from silicon into SiO2. A focused spot of light is scanned over the surface of the sample to determine lateral variations of the photocurrent. We compare data taken before and after a treatment that has caused positive ions to drift to the interface. Before the treatment, the photocurrent is uniform in magnitude over the surface. After the treatment there are very pronounced local peaks. The results from scanning photoemission are combined with measurements of C-V characteristics, photovoltage, and the voltage dependence of photocurrent to obtain a fuller explanation of the effects of ion drift. Peaks in the photoemission current are sometimes, but not always, associated with a lower interface barrier. In some cases where the peaks are especially pronounced they coincide with the points of first breakdown on voltage stress.
Electrical properties and luminescence of alloys of gallium phosphide and zinc selenide
Authors: Yu Phil Won , Glicksman Maurice
Published: February 2004

Crystals of alloys of GaP with ZnSe have been grown with ZnSe contents up to 8 mole%. Study of the transport properties of n-type samples of such alloys showed a hopping contribution to the conductivity at low temperatures, with an activation energy of 4 meV, and the dominance of ionized impurity scattering above about 150 K. The cathodoluminescence of the alloy crystals showed no Zn–Se donor-acceptor-pair recombination lines. Diodes fabricated from the alloy material (by the diffusion of Zn as an acceptor impurity) showed electroluminescence at room temperature (and below), although weaker than that found for GaP diodes by as much as two orders of magnitude. Identifiable pair-recombination emission in the alloy diodes decreased slightly in energy with alloying, from 1.95 to 1.91 eV on going from 0 to 5% ZnSe. This shift may be in part chemical.
The Monte Carlo technique as applied to the fundamentals of EPMA and SEM
Authors: Shimizu Ryuichi , Ikuta Takashi , Murata Kenji
Published: February 2004

A Monte Carlo technique was applied to study the fundamental phenomena in the electron probe microanalyzer (EPMA) and the scanning electron microscope (SEM), which are brought about by scattering of the primary electrons in a specimen. The calculation procedure was based on Lewis' multiple scattering theory; however, some attempts were made to improve it by introducing the substeps to each step which had been used in previous calculations. The main purpose is to investigate the applicability of this improvement through the comparison with the experimental results with respect to backscattered electrons obtained by Kanter, and next to give a theoretical explanation for the experimental results of Wells as well as to obtain more detailed information on the electron backscattering. The results show that the fidelity of the present Monte Carlo simulation for the electron backscattering is satisfactory.
Drag force on a magnet moving near a thin conductor
Authors: Davis L. C.
Published: February 2004

For a magnet moving with velocity ν over a conducting sheet, a proof of the relationship, drag force=(w/ν) (lift force), based upon Poynting's vector, is given. w is a characteristic velocity determined by the conductance of the sheet. A similar result for a right-angle corner, drag force = (w/ν) (lift force + guidance force), is proved in the high-speed limit by considering Maxwell's stress tensor.
Further information on the mechanism of photoconductivity in chemically deposited lead sulfide layers
Authors: Lee Eal-Hyung , Bube Richard H.
Published: February 2004

The mechanism of photoconductivity in chemically deposited lead sulfide layers on ceramic SrTiO3 substrates has been examined by measurements of electrical conductivity, Hall effect, photo-Hall effect, and dc and ac photoconductivity. The information obtained is supplementary to that reported by Espevik et al. It confirms further that the dark-conductivity process with barrier-controlled mobility is completely independent of preparation procedure and substrate, and indicates the presence of sensitizing centers for p-type photoconductivity located 0.22 and 0.13 eV below the conduction band.
Enhanced optical four-proton parametric interaction in a low-dispersive liquid
Authors: Giuliani J. F.
Published: February 2004

An enhanced optical parametric interaction has been observed in a liquid possessing an unusually low optical dispersion over the visible infrared spectral region. The entire liquid path was utilized in mixing two external laser beams.
Correction to the elastic constants of AISb
Authors: Weil Raoul
Published: February 2004

The elastic constants of AISb are recalculated using the correct value for the density of this compound. The corrected elastic constants are C11 = 8.769,c12 = 4.341, and C44 = 4.076 in units of 1011 dyn/cm2.
Preferred orientation of crystallites in uniaxially deformed polytetrafluoroethylene
Authors: Wecker Sheldon M. , Davidson Theodore , Baker David W.
Published: February 2004

X-ray methods have been used to determine the preferred orientation of crystallites in PTFE sheets stretched varying amounts in the trigonal phase at room temperature. Spherical harmonic analysis of the x-ray data was carried out to obtain inverse pole figures. At high elongations results show preferential alignment of the c axis (chain direction) with the extension axis. At lower elongations there is also a tendency for (h0h̄l) poles to be aligned with the extension axis. The results at low extension are interpreted as being caused by slip occurring on {1120} planes along the tangent to the helix formed by the PTFE molecule. Experiments carried out in the hexagonal phase above 30°C, and in the triclinic phase below 19°C support these conclusions.
Grüneisen parameters of crystalline polyethylene
Authors: Wu C. K. , Jura G. , Shen M.
Published: February 2004

Values of the Grüneisen parameter γ reported in the literature for polyethylene (PE) vary over nearly four orders of magnitude. Part of the reason for this wide variation is the variety of definitions and experimental techniques used in obtaining γ. A simple unified derivation of these equations will be presented in an attempt to clarify the interrelations among them. Underlying assumptions used in arriving at these equations will be pointed out. Infrared spectra of a bulk polyethylene were taken at room temperature up to 40-kbar pressures. Microscopic Grüneisen parameters were obtained from these data for rocking and bending modes of PE. It will be demonstrated that values of the Grüneisen parameters are dependent on lattice frequency, volume, wave vector, and degree of crystallinity for PE.
Accommodation of the stress field at a grain boundary under heterogeneous shear by initiation of microcracks
Authors: Das E. S. P. , Marcinkowski M. J.
Published: February 2004

Polycrystalline deformation leads to the creation of deformation ledges at grain boundaries undergoing heterogeneous shear. The large strain fields of the deformation ledges can be relieved either by nucleation of further slip or by initiation of microcracks to accommodate the interface strains set up by the deformation of adjacent grains. The formation of accommodation microcracks from the deformation ledges is considered in detail. It is shown that the type of the accommodation microcrack—tensile or shear, transgranular or intergranular—depends on the type of the deformation ledge, and can be spontaneously nucleated. Stability, equilibrium, and the shape of the microcrack are determined from a discrete dislocation approach. Computer techniques are used in this study and the results are compared with those of the continuum mechanics approach. The effect of the application of an external stress is considered in detail and it is shown that a given stable microcrack has a critical stress at which it becomes unstable with respect to unlimited extension. Growth of a microcrack at a stress smaller than the critical stress is studied as a heterogeneous growth.