bluuebunny/crossref_metadata_2025 huggingface dataset:
Attenuation and phase velocity of surface acoustic waves interacting with charge carriers in thin metal films
Authors: Harnik E. , Sader E.
Published: February 2003

A simple method for the simultaneous measurement of attenuation and phase-velocity changes of surface acoustic waves, based on the use of a surface-acoustic-wave oscillator, is described. The application of the method is illustrated in the case of surface acoustic waves interacting with charge carriers in thin gold fims vapor deposited on the lithium niobate substrate supporting the surface waves. Good agreement is obtained between experimental results and theory. It is shown that the product of carrier mobility and Fermi energy can be determined with good accuracy independently from three different relations involving attenuation, phase velocity, and resistivity data.
Trap depth and electron capture cross section determination by trap refilling experiments in Schottky diodes
Authors: Zylbersztejn A.
Published: February 2003

It is shown that the time-dependent capacitance change associated trap refilling in a Schottky diode is nonexponential, consisting in the sum of two contributions which reduce to a single one for reverse biases smaller than VSCO, the space-charge crossover voltage. Determination of VSCO yields both the trap depth ΔE and its capture cross section. This is experimentally demonstrated for the oxygen-related trap in n-GaAs. We find ΔE=0.67 eV in good agreement with other determinations.
Electrochromism in anodic iridium oxide films
Authors: Gottesfeld S. , McIntyre J. D. E. , Beni G. , Shay J. L.
Published: February 2003

The oxidation state of iridium ions in an oxide film grown electrochemically on an Ir metal reflector electrode in aqueous 0.5M H2SO4 electrolyte can be rapidly and reversibly modulated by voltage pulses of 1 V amplitude according to the reaction: Ir(OH)n(transparent) ⇄IrOx(OH)n−x(colored)+xH++xe. This valency interconversion produces a marked change in light absorption throughout the visible wavelength region and occurs without change in film thickness. Color-bleach cycles exhibit reflectance contrast changes, ΔR/R, and charging times, τ, suitable for electrochromic display devices, e.g., for a film 700 Å thick: ΔR/R=60% at λ=546 nm and τ≈40 msec. The fast write-erase times are made possible by the highly porous and hydrated nature of the oxide film. The charge (∼20 mC cm−2) and energy (∼20 mJ cm−2) are comparable with those for other electrochromic oxide systems, e.g., the tungsten bronzes. Advantages of the iridium oxide system include: (i) fast response; (ii) stability of the colored written state in the presence of water and dissolved O2; (iii) broad spectral absorption; and (iv) the ability to grow and reform the oxide layer insitu in the electro-optic display cell. Electrochromic spectra of anodic iridium oxide films are illustrated and related to charge-transfer and intervalency transitions.
Tunable optical waveguide directional coupler filter
Authors: Alferness R. C. , Schmidt R. V.
Published: February 2003

An integrated optical filter composed of coupled nonidentical strip waveguides in LiNbO3 is demonstrated. The device has a 200-Å bandwidth, is tunable over several hundred angstroms, and offers electrical control of the crossover efficiency.
Gain and saturation of the nitrogen ion laser
Authors: Collins C. B. , Carroll J. M. , Taylor K. N.
Published: February 2003

In this work a dilute nitrogen plasma pumped by charge transfer from He+2 has been operated as a pulsed optical amplifier. In the experimental system used two synchronously excited plasmas were produced by preionized discharges in an atmospheric electrical avalanche device switched by hydrogen thyratrons so that repetitive operation to 30 Hz would be possible. The plasmas were electrically connected in a transverse series circuit to provide a phase delay in their excitation comparable to the optical transit time between them. Laser output at 427.8 nm from the first discharge coupled to the fields in a self-excited oscillator geometry was threaded through the second along its 85-cm longer dimension. Calibrated attenuation of the beam from the oscillator subsequently input to the amplifier provided data on the overall amplification ratio to which the two adjustable parameters of a simple model were fit. From these parameters overall small-signal gains as large as 2×106 were found together with saturation intensities of the order of 50 kW/cm2. Under the same conditions a gain of about 18 was found at an output intensity of 1 MW/cm2, conditions relatively near the ideal extraction of power at zero gain.
UHF single-phase line acoustic wave transducers
Authors: Hoskins Michael J. , Datta Supriyo , Hunsinger Bill J.
Published: February 2003

The feasibility of line acoustic wave delay lines at high frequencies using single-phase transducers is demonstrated. Experimental results are presented for a 219.5-MHz device and it is expected that much higher frequency devices are possible.
A new effect in multiphoton photoeffect of a gold surface induced by picosecond laser pulses
Authors: Lompre L. A. , Mainfray G. , Manus C. , Thebault J. , Farkas Gy. , Horvath Z.
Published: February 2003

A bandwidth-limited 15-psec laser pulse is used to induce multiphoton photoelectric emission from a gold metal cathode. The wavelength is tuned between 10 580 and 10 620 Å to investigate the transition from a four-photon to a five-photon photocurrent j from a gold surface. This transition gives rise to a new effect marked by a dramatic change of the slope n=∂ logj/∂ logI, where I is the laser intensity.
High-efficiency p+-n-n+ back-surface-field silicon solar cells
Authors: Fossum J. G. , Burgess E. L.
Published: February 2003

The design and fabrication of high-efficiency p+-n-n+ back-surface-field silicon solar cells are described. The fabrication process has been developed to yield maximum attainable carrier lifetimes (∼0.7 msec) in the base region of the cell, thereby allowing the back n-n+ junction to effectively enhance the cell performance. A surprising conclusion drawn from a study of the device physics supporting the experimental development of the cell is that the front-surface recombination velocity controls the recombination in the emitter. That is, the bulk p+ emitter is ’’transparent’’ to minority-carrier (electron) flow. The recognition of the significance of the front silicon surface has led to process modifications that result in improvements in both the short-circuit current density and the open-circuit voltage of the cell. With these improvements, the cells exhibit AMl conversion efficiencies of nearly 17%. The fabrication process is reliable and reproducible with exceptionally high yield.
Ultralinear bistable electro-optic polarization modulator
Authors: Feldman Albert
Published: February 2003

An optical device utilizing optical feedback has been constructed with a Pockels cell and polarizing components. Two modes of operation of the device are demonstrated. Both modes exhibit optical bistability. It is demonstrated that in one mode of operation the nonlinear dependence of the output intensity as a function of an input optical or electrical signal can be made arbitrarily small compared to the linear dependence.
The kinetics of latent-image formation in electrophotography with photoferroelectrics
Authors: Berg W. F. , Fridkin V. M. , Günter P. , Stähli H.
Published: February 2003

The anomalous photovoltaic effect in ferroelectrics is capable of producing imagewise distributions of voltages sufficiently high to allow for conventional xerographic development. The electric latent image will persist for long periods of time. The kinetics of the buildup of photovoltage has been studied on undoped LiNbO3 and shown to conform to theoretical expectations: the saturation values of the field strongly depend on light intensity.
New technique for identification of deep-level trap emission to indirect conduction minima in GaAs
Authors: Majerfeld A. , Bhattacharya P. K.
Published: February 2003

A new analysis of the C-V characteristics of the depletion region of a Schottky barrier in the presence of deep-level traps is presented which yields the absolute position of the energy level in the energy band diagram. It is found that for the commonly observed 0.830±0.005 eV electron trap in VPE GaAs, the level is located at 0.543 eV (240 K) and 0.537 eV (120 K) below the Γ conduction minimum. It is shown that this level emits electrons to the L minima and, that relative to these minima, exhibits a zero temperature coefficient. The capture cross section for this center is σ∞= (1.8±0.4) ×10−14 cm2 and has a zero activation energy over the temperature interval 120–240 K.
Critical currents in sputtered PbMo6S8
Authors: Alterovitz Samuel A. , Woollam John A. , Kammerdiner Lee , Luo Huey-Lin
Published: February 2003

Critical currents in sputtered Chevrel-phase lead molybdenum sulphide have been measured at several temperatures as a function of applied magnetic field up to 19 T. We find a critical current density of ∼5×107 A/m2 at 15 T and 1.8 K, and the effective upper critical field was estimated to be 30 T. The pinning force at low fields was found to be dependent on the amount of free lead.
Oxide thickness effects on electron scatterings at a thermally grown Si-SiO2 interface
Authors: Yagi A. , Kawaji S.
Published: February 2003

The effective electron mobility of N-channel MOSFET’s with different gate oxide thickness has been measured at 4.2 K as a function of electron density. An increase in the peak effective mobility is observed as the oxide thickness is increased. It is found that the peak mobility is determined by the scattering mechanism whose scattering probability is independent of electron density. To describe these experimental results, the scattering by a short-ranged potential has been assumed and discussed.
Generation of coherent tunable Josephson radiation at microwave frequencies with narrowed linewidth
Authors: Varmazis C. , Sandell R. D. , Jain A. K. , Lukens J. E.
Published: February 2003

Coherent tunable microwave radiation (2–18 GHz) has been observed from two microbridge Josephson junctions coupled by a shunt resistor. The coherent power (∼4×10−12 W) is nearly four times the power emitted by a single junction. The linewidth of the radiation in the coherent state is one-half that from the individual microbridges.
Observation of phase separation in a Cr-Co-Fe alloy (chromindur) by Mössbauer effect
Authors: Eibschütz M. , Chin G. Y. , Jin S. , Brasen D.
Published: February 2003

Mössbauer effect measurements of 57Fe in a Cr-Co-Fe alloy indicate the existence of two ferromagnetic phases at room temperature. The hyperfine field of the two phases differ by ∼11%. This result implies that domain-wall–particle interaction is responsible for the coercive force, which is a different mechanism than in some Alnico alloys.
Combustor-driven CO chemical laser
Authors: Richardson R. J. , Wiswall C. E.
Published: February 2003

Operation of the first supersonic combustor-driven purely chemical CO laser is reported. The combustor is fueled with NF3-CH4-H2-CS2 and produces a mixture of HF, N2, CS, CS2, and S which is mixed with dry air and N2O during a supersonic expansion into the laser cavity. A chain reaction involving CS and O2 is initiated by the S atoms and produces CO with a non-Boltzmann vibrational-rotational energy-level population distribution. The laser produces 450 W of closed-cavity power as determined by mirror calorimetry.
Ambient gas influence on photoluminescence intensity from InP and GaAs cleaved surfaces
Authors: Nagai Haruo , Noguchi Yoshio
Published: February 2003

The reversible change in photoluminescence intensity with change in gaseous ambients (N2, Ar, H2, O2, H2O, and vacuum) from a InP cleaved (110) surface and the irreversible change in photoluminescence from a GaAs cleaved (110) surface when exposed to oxygen were observed at room temperature. These phenomena imply that adsorbed N2, H2, Ar, H2O, and O2 gases can be exchanged reversibly on the InP surface, and the surface recombination velocity changes reversibly with the adsorbed gas species. On the other hand, oxidation proceeds rapidly and irreversibly on GaAs cleaved surfaces.
Elongation of pulsed oscillation of an H2O laser
Authors: Kido G. , Miura N.
Published: February 2003

The duration time of pulsed oscillation of an H2O laser was considerably elongated at 16.93, 27.97, and 36.60 μm, by adding large amount of helium gas to the discharge. The admixture of He was also effective in enhancing the output power.
High-efficiency stimulated Raman scattering/dye radiation source
Authors: Decker C. David
Published: February 2003

The development of a high peak and average power stimulated Raman scattering (SRS) source with a dye amplifier is described. Emission from 505 to 771 nm is obtained using 532-nm radiation from a frequency-doubled Nd : YAG laser as the optical pump. Dimethyl sulfoxide (DMSO) is found to be a very efficient SRS medium, and produces 40% energy conversion from 532 to 630 nm at 10 pulses/sec. Use of a dye amplifier increases energy conversion efficiency to 60%. Mixtures of DMSO and d-DMSO are found to emit the I and II Stokes lines of each material, plus a ’’mixed’’ mode line at 727 nm. SRS is also shown to be a limiting phenomenon in the power scaling of laser-pumped dye lasers.
Inversion of the Na resonance line by selective photodissociation of NaI
Authors: White J. C.
Published: February 2003

This letter reports the inversion and intense superfluorescent emission of the Na resonance line by selective photodissociation of NaI. The fifth harmonic of a Q-switched Nd : YAG laser at 2128 Å was used to photodissociate NaI to the unbound state Na(3p 2P)+I(5p5 2P3/2). Superfluorescence at the 5896-Å resonance line was observed.
Effect of preacceleration on intense ion-beam transmission efficiency
Authors: Whealton J. H. , Tsai C. C. , Dagenhart W. K. , Gardner W. L. , Haselton H. H. , Kim J. , Menon M. M. , Ryan P. M. , Schechter D. E. , Stirling W. L.
Published: February 2003

Utilization of a preacceleration potential to accelerate ions before they reach the emission aperture results in a substantial increase in the transmission efficiency. For an intense modified duoPIGatron focused multibeamlet (1799 apertures) 22-cm-diam ion source, the total transmission efficiency for beam power through an aperture 20×25 cm located 4.10 m downstream increased 30%. This result is in agreement with a previous solution to the appropriate two-dimensional Poisson-Vlasov equation for ions extracted from a plasma.
Laser-beam annealing of heavily damaged implanted layers on silicon
Authors: Muller J. C. , Grob A. , Grob J. J. , Stuck R. , Siffert P.
Published: February 2003

The behavior during annealing of heavily doped silicon layers obtained by a high-current-density ion implantation, realized by discharge in BF3 atmosphere, is investigated. The annealing is performed by a laser pulse and the surface layers are studied by Rutherford backscattering, SIMS, and conductivity measurements. Comparisons with thermal annealing show the advantage of using laser pulses to restore the original crystallinity.
Time-resolved reflectivity of ion-implanted silicon during laser annealing
Authors: Auston D. H. , Surko C. M. , Venkatesan T. N. C. , Slusher R. E. , Golovchenko J. A.
Published: February 2003

The time-resolved reflectivity at 0.63 μm from arsenic-implanted silicon crystals has been measured during annealing by a 1.06-μm laser pulse of 50-ns duration. The reflectivity was observed to change abruptly to the value consistent with liquid silicon and to remain at that value for a period of time which ranged from a few tens of nanoseconds to several hundreds of nanoseconds, depending on the annealing pulse intensity. Concurrently, the transmission of the primary annealing beam dropped abruptly. These observations confirm the formation of a metallic liquid phase at the crystal surface during the annealing process.
Capture cross section of gold in silicon
Authors: Nassibian A. G. , Faraone L.
Published: February 2003

Experiments to determine generation lifetime and capture cross section of gold in n-type silicon were performed using the non-steady-state linear voltage ramp technique. Measurements were carried out on MOS devices with different gold concentrations, obtained by various diffusion times of 10, 20, 40, and 100 min at 900 °C. It is found that in the temperature range 235–265 °K, the capture cross section is temperature dependent and has a value of the order of 1.0×10−15 cm2.
Amorphous ferromagnetic thin films
Authors: Kobliska R. J. , Aboaf J. A. , Gangulee A. , Cuomo J. J. , Klokholm E.
Published: February 2003

Amorphous ferromagnetic thin films containing one or more transition metals and one or more glass formers have been fabricated by sputtering. Typical magnetic properties of these thin films are comparable to those of bulk amorphous alloys with corresponding compositions. Thermal stability and annealing characteristics of these amorphous thin films are discussed.
250-Å linewidths with PMMA electron resist
Authors: Broers A. N. , Harper J. M. E. , Molzen W. W.
Published: February 2003

25-nm-wide lines and spaces have been fabricated in 22.5-nm-thick films of PdAu (40 : 60) using electron-beam exposure and polymethylmethacrylate (PMMA) resist. A high-resolution scanning transmission electron microscopy (STEM) was used to expose the resist and the samples were mounted on 60-nm-thick Si3N4 membrane substrates. Previously, the smallest metal structures formed with a resist process were 60 nm wide with spaces between the lines several times larger than the lines. The results presented here show that 25-nm lines can be fabricated with a center to center spacing of 50 nm.
Acoustic-emission study of defects in GaP light-emitting diodes
Authors: Ikoma T. , Ogura M. , Adachi Y.
Published: February 2003

Acoustic emission was detected during the degradation of GaP : N light-emitting diodes and was shown to have a correlation with the generation of dislocations near the p-n-junction plane. This technique provides us with a powerful tool to investigate dislocation motion on real time and in a nondestructive way.
1.0–1.4-μm high-speed avalanche photodiodes
Authors: Law H. D. , Tomasetta L. R. , Nakano K. , Harris J. S.
Published: February 2003

High-speed high-quantum-efficiency avalanche photodiodes (APD’s) are required in the 1.0–1.4-μm wavelength range in order to exploit the superior optical fibers now available at these wavelengths. The GaAlSb heterojunction APD’s reported here have external quantum efficiencies of 60% (without antireflection coatings), risetimes of 60 ps, and pulse widths (FWHM) of 120 ps with no evidence of a ’’back porch’’. Uniform high-speed avalanche gains of 20 have been achieved.
A cesium plasma TELEC device for conversion of laser radiation to electric power
Authors: Britt E. J. , Rasor N. S. , Lee G. , Billman K. W.
Published: February 2003

The first tests of the thermoelectronic laser energy converter (TELEC) concept are reported. This device has been devised as a means to convert high-average-power laser radiation into electrical energy, a crucial element in any space laser power transmission scheme using the available high power/efficiency infrared lasers. Theoretical calculations, based upon inverse bremsstrahlung absorption in a cesium plasma, indicate internal conversion efficiency up to 50% with an overall system efficiency of 42%. Experiments reported here were made with a test cell designed to confirm the theoretical model rather than demonstrate efficiency; 10.6-μm laser-beam absorption was limited to ∼10−3 of the incident beam by the short absorption region. Nevertheless, confirmatory results were obtained and the conversion of absorbed radiation to electric power is estimated to be near 10%.
Non-Gaussian fundamental mode patterns in narrow-stripe-geometry lasers
Authors: Asbeck P. M. , Cammack D. A. , Daniele J. J.
Published: February 2003

Near- and far-field patterns of narrow (⩽10 μm) stripe-geometry lasers are reported which differ significantly from the Gaussian patterns predicted and observed in wider-stripe lasers. The field patterns are explained by using a waveguide model which takes into account the finite extent of the stripe. High-output-power operation in a single fundamental transverse and lateral mode (up to 1 W in 25-ns pulses) has been observed in devices of this type.
Second-harmonic generation in Ti-diffused LiNbO3 optical waveguides with 25% conversion efficiency
Authors: Sohler W. , Suche H.
Published: February 2003

Using a tunable optical parametric oscillator, phase-matched second-harmonic generation was realized in high-quality Ti-diffused LiNbO3 optical waveguides near the 1.08-μ fundamental wavelength. At 45 W peak power in 17-mm-long waveguides an efficiency for TM0→TE1 conversion up to 25% was achieved. This value is three orders of magnitude larger than previously published results.
Efficient operation of the electron-beam-pumped XeCl laser
Authors: Champagne L. F.
Published: February 2003

Efficient operation (5.0%) of the long-pulse (0.5 μsec) XeCl laser is obtained by electron-beam pumping of mixtures of neon, xenon, and HCl. Laser emission is observed at 308.0 and 308.2 nm. A small-signal gain of 2.6% cm−1 is measured from which the saturation intensity is calculated to be ∼0.35 MW cm−2 and the optical absorption at the laser wavelength is calculated to be ∼0.26% cm−1. The electron-beam-pumped XeCl laser can be operated under static fill conditions with no measurable degradation in output power.
Thin InAs epitaxial layers grown on (100) GaAs substrates by molecular beam deposition
Authors: Meggitt B. T. , Parker E. H. C. , King R. M.
Published: February 2003

Thin heteroepitaxial layers of InAs have been grown on (100) GaAs substrates and buffer layers by molecular beam deposition in a UHV chamber. Smooth epitaxial layers as indicated by in situ MEED patterns have been obtained at substrate temperatures in the range 330–530 °C and SEM micrographs and electron channeling patterns taken ex situ have confirmed these properties. MEED observations also indicated that epitaxial growth can be obtained at considerably lower deposition temperatures. InAs films, 0.5–2.0 μm thick, grown between 330 and 530 °C had bulklike electrical properties with residual n-type carrier concentrations in the range 5×1016 to 1×1018 cm−3, the lowest values occurring for depositions at 530 °C.
Solid-phase epitaxy of implanted silicon by cw Ar ion laser irradiation
Authors: Williams J. S. , Brown W. L. , Leamy H. J. , Poate J. M. , Rodgers J. W. , Rousseau D. , Rozgonyi G. A. , Shelnutt J. A. , Sheng T. T.
Published: February 2003

Arsenic- and antimony-implanted silicon wafers have been annealed by a cw Ar ion laser. Glancing-angle Rutherford backscattering and transmission electron and optical microscopy measurements indicate that the mechanism for recrystallization is one of thermal solid-phase regrowth from the underlying crystalline-amorphous interface. No implant redistribution is observed.
Optical reflectivity of ion-implanted amorphous GaAs
Authors: Grasso V. , Mondio G. , Saitta G. , Campisano S. U. , Foti G. , Rimini E.
Published: February 2003

The reflectivity of single-crystal and amorphous GaAs samples was measured in the photon energy range 1.5–7.0 eV. The amorphous specimens were obtained by 400-keV Te implantation at room temperature. Some structures at high photon energy are still present in the imaginary part of the dielectric function for the Te-implanted GaAs. The optical properties of such an amorphous layer differ noticeably from those reported in literature for flash-evaporated films. The difference may be attributed to the lack of stoichiometry in the deposited layers.
Nonalloyed Ohmic contacts to n-GaAs by molecular beam epitaxy
Authors: Barnes P. A. , Cho A. Y.
Published: February 2003

We report the formation of Ohmic contacts to n-GaAs without the need for a high-temperature alloy. Heavily doped n-GaAs(Sn) was grown using molecular beam epitaxy in which the concentration of free carriers was as high as ‖ND−NA‖=6×1019 cm−3 yielding specific contact resistance rc=1.86×10−6 Ω-cm2.
Arbitrary doping profiles produced by Sb-doped Si MBE
Authors: Bean John C.
Published: February 2003

Arbitrary doping profiles with abrupt transitions have been produced in n-type Si MBE films. Changes in doping level were produced with a resolution unattainable by CVD growth and at depths inaccessible to ion implantation. It was found, however, that films must be grown above ∼850 °C. Below that temperature doping profiles were distorted and Sb segregated strongly on the sample surface.
Angle-resolved photoemission measurements of band discontinuities in the GaAs-Ge heterojunction
Authors: Perfetti P. , Denley D. , Mills K. A. , Shirley D. A.
Published: February 2003

The conduction- and valence-band discontinuities for the (110) GaAs-Ge heterojunction have been measured as ΔEc=0.50 eV and ΔEv=0.25 eV by the angle-resolved ultraviolet photoemission (ARUPS) technique. These values are in good agreement with the theoretical predictions of Pickett et al.
Applicability of the Scher-Montroll model to transient photocurrent and surface potential decay in insulators
Authors: Perlman M. M. , Bamji S.
Published: February 2003

Transient photocurrent measurements in anthracene crystals and surface potential decay measurements in polyethylene and phthalocyanine films show that care must be taken when applying the normalized logI-vs-logt plot of the Scher-Montroll model to determine transit times. In all three materials, two intersecting straight lines were obtained in the featureless time region beyond previously measured transit times. It is suggested that for the particular fields and thicknesses of samples used, the transit time may be too short to observe by the particular experimental method used, or that the carriers may never reach the rear electrode. In both cases featureless decay curves will be observed, and the logI-vs-logt plot can predict erroneous results. Universality seems to be generally obeyed.
Depolarization of photoelectrons emitted from optically pumped GaAs
Authors: Erbudak M. , Reihl B.
Published: February 2003

The spin polarization of photoelectrons emitted from optically pumped negative electron affinity GaAs shows a systematic depolarization. This is attributed to the spin-flip scattering at the Cs-O-Cs overlayer. The photoexcited electrons thermalize to the Γ point prior to their escape and hence go through the overlayer with the same kinetic energy resulting in photon-energy-independent polarization loss.
High-efficiency Cr-MIS solar cells on single and polycrystalline silicon
Authors: Anderson W. A. , Delahoy A. E. , Kim J. K. , Hyland S. H. , Dey S. K.
Published: February 2003

Cr-MIS solar cells having a 2-cm2 area have been fabricated to produce 12.2% efficiency on single crystal and 8.8% efficiency on polycrystalline Si. Surface-state data were used to predict open-circuit voltages of 0.60 and 0.50 V, respectively, for the single-crystal and polycrystalline Si. Spectral response measurements and Cr metal thickness confirm the differences in short-circuit current density using these two types of Si.
The importance of the electron affinity of oxide-semiconductors as used in solar cells
Authors: Singh R. , Shewchun J.
Published: February 2003

The electron affinity of oxide semiconductors (In2O3,SnO2, etc.) is a topic of current interest. These materials are capable of forming barrier devices on a number of semiconductors which exhibit good photovoltaic conversion efficiency. We will show that simple methods based on the electrical measurements of oxide-semiconductor/base-semiconductor systems often lead to incorrect results, due to the uncertainty in the Fermi-level position in the oxide-semiconductors and other interface parameters. To determine the true potential of a particular oxide-semiconductor, other methods should be used to find the electron affinity.
Vapor-grown InGaP/GaAs solar cells
Authors: Olsen G.H. , Ettenberg M. , D’Aiello R. V.
Published: February 2003

GaAs solar cells with conversion efficiencies as high as 14% at AM1 have been grown by the GaCl/AsH3 hydride technique. Thin (∼200 Å) layers of InGaP were used to passivate the GaAs top surface. We observe a 70-fold increase in photoluminescence intensity of the GaAs after passivation, which is consistent with a lowering of the GaAs surface recombination velocity from ≳106 to <104 cm/sec. Short-circuit current densities (Jsc) as high as 22 mA/cm2 and open-circuit voltages as high as 0.96 V were observed. (If achieved together, those values would yield an efficiency of almost 18%.) Voc was observed to increase directly with p-layer thickness (t), whereas Jsc decreased directly with t. The efficiency also increased as the zinc doping was decreased.
Photon detection in nonlinear tunneling devices
Authors: Tucker J. R. , Millea M. F.
Published: February 2003

A quantum generalization of classical microwave mixer theory is developed to project the performance of nonlinear tunneling barriers at high frequencies. The results demonstrate that such devices may be considered photon detectors when their conductance varies rapidly on a scale of voltage h/ω/e. Tunnel barrier mixers are thus shown to offer potential for the development of wide-band quantum noise limited detectors in the wavelength region from 10 μm to a few millimeters.
XeF excimer pumping of Nd : P5O14
Authors: Wilson Jack , Brown David C. , Zwicker Walter K.
Published: February 2003

We report the first excimer (XeF) pumping of Nd3+ in a pentaphosphate (Nd : P5O14) host. Absorption of the XeF laser output of 3530 Å by the Nd3+ transition (4I9/2→4D3/2) results in laser output at the 1.05-μ transition (4F3/2→4I11/2). Pumped in an oscillator configuration, threshold energy was only ≃3 mJ while slope efficiency was ≃1%. Temporal output consists of a single pulse of duration (FWHM) ≃6.6 ns; it arises due to the combination of short pump pulse (≃24 ns FWHM) and high gain of the pentaphosphate output. The device is expected to find considerable application in producing short (1–10 ns) pulses without the complication of a Q switch required in conventional flashlamp-pumped lasers.
Beam scanning and wavelength modulation with branching waveguide stripe injection lasers
Authors: Scifres D. R. , Streifer W. , Burnham R. D.
Published: February 2003

The operation of a branching waveguide stripe-geometry semiconductor injection laser is described. This structure produces interference fringes in the far field which are spatially scanned by electrically varying the optical phase in each leg of the branched waveguide in a manner analogous to microwave phased array radar. Moreover, the output spectral peak of the laser also varies periodically over 70 Å with these electrically induced phase shifts.
Control of storage and writing times in the diode storage correlator
Authors: Loh K. W. , Schroder D. K. , Emtage P. R.
Published: February 2003

In Si junction diodes it is possible to achieve a short recombination time together with a large storage time at room temperature by deliberately introducing impurities with asymmetric trapping levels, such as Pt, into the region of the junction. It is shown that this technique can be used in surface-acoustic-wave devices to increase the bandwidth by reducing the writing time on a junction memory to 5×10−9 sec while the storage time remains above 0.2 sec.
Electrochromism of heat-treated anodic iridium oxide films in acidic, neutral, and alkaline solutions
Authors: Beni G. , Shay J. L.
Published: February 2003

We show that coloration and bleaching times of anodic iridium oxide films (AIROF’s) are insensitive to pH. Similar kinetics are observed for aqueous solutions of 0.5M H2SO4, 4M LiNO3, or 0.5M NaOH, and for a solution of 3M LiNO3 in methanol. This suggests that long-term stability may be achieved without degrading response time. It also shows that the mechanism for electrochromism in AIROF’s is fundamentally different from the ion-electron double-injection operative in the tungsten bronzes and recently proposed for AIROF’s. In fact it appears to be sufficient that current flow across the AIROF solution interface be carried solely by electrons. We also show that AIROF’s have markedly improved bleaching kinetics, reproducibility, and stability following heat treatment.
Low-temperature migration of Si into Au/Pt thin films on Si substrates with an interposed Cr layer, investigated by two methods of depth analysis
Authors: Mladenov G. M. , Emmoth B.
Published: February 2003

By optical detection of excited sputtered particles, depth analysis of a multilayer film on a Si substrate was carried out and low-temperature migration of Si was studied. For complementary information, Rutherford backscattering analysis of all samples was performed. A comparison between the two methods shows that the optical method is well suited for Si migration studies. As a result, it was found that Si penetrated through a 100-Å-thick Cr film into the top metal layers of Pt and Au after heat treatment in the temperature range 350–400 °C. It was also found that a 400-Å Cr film acted as an effective barrier for Si migration under similar conditions.
Internal electroabsorption in inverted heterostructures: An optical method for probing epitaxial layers
Authors: Bottka N. , Hills Marian E.
Published: February 2003

Modulation internal electroabsorption was used to determine the gap energies and the presence of interface potentials of multilayered epitaxial n-n GaAs1−xSbx heterostructures. Experimental results indicate the presence of deep potential wells at the interface between epitaxial layers due to large net density of interface states. In addition to the observed band-to-band transitions in the epitaxial layers, it was possible to resolve transitions between filled and empty quantized states at the interface between the two epitaxial layers.
Observation of an intermediate chemical state of silicon in the Si/SiO2 interface by Auger sputter profiling
Authors: Helms C. R. , Strausser Y. E. , Spicer W. E.
Published: February 2003

We have observed, for the first time, a chemical state of silicon different from that of the pure bulk silicon or silicon in SiO2, using Auger electron spectroscopy. In the E N (E) spectra this state gives a major transition at 83.3 eV compared to 90.3 eV for bulk Si and 74.2 eV for SiO2. We have observed this state both at the Si/SiO2 interface of MOS oxide structures during sputter profiling and for thin native oxides without sputtering. The state is difficult to see in the dE N (E)/dE spectra due to the presence of the sharp edge of the free silicon peak at 92 eV which tends to mask it.
Some effects of planar defects near the Si/SiO2 interface on electrical properties of silicon-on-sapphire/MOS devices
Authors: Abrahams M. S. , Ham W. E.
Published: February 2003

Data are presented which show some primary effects of widely different planar defect densities (at the top surfaces of the films) on the electrical properties of silicon-on-sapphire/MOS devices. These electrical properties are directly related to the microstructure of the films using transmission electron microscope methods. Both surface mobility and effective surface threshold potential are found to depend strongly on the surface defect density. Specimens having surface densities of 3×104 and 4×105 cm−1 were examined.
cw laser anneal of polycrystalline silicon: Crystalline structure, electrical properties
Authors: Gat A. , Gerzberg L. , Gibbons J. F. , Magee T. J. , Peng J. , Hong J. D.
Published: February 2003

0.4-μm-thick polycrystalline silicon deposited in a low-pressure CVD reactor was implanted with B to a dose of 5×1014/cm2 and then irradiated in a cw laser scanning apparatus. The laser annealing produced an increase in grain size from ∼500 Å to long narrow crystals of the order of ∼25×2 μ, as observed by TEM. Each grain was found to be defect free and extended all the way to the underlying Si3N4. Electrical measurements show 100% doping activity with a Hall mobility of about 45 cm2/V sec, which is close to single-crystal mobility at the same carrier concentration. Thermal annealing produces material with an average grain size of 1000 Å and a resistivity higher by a factor of 2.2 than that obtained with the laser anneal. Laser annealing performed after a thermal anneal reduces the resistivity to approximately the same value obtained by laser annealing only.
Josephson logic circuits based on nonlinear current injection in interferometer devices
Authors: Gheewala T. R.
Published: February 2003

Nonlinear current-injection switching of Josephson interferometer devices is achieved by current injection into an asymmetric feedpoint. This method of switching interferometers has two important features: higher gain than in previous approaches and a novel nonlinear threshold curve which is of practical interest. A new family of high-performance logic gates based on nonlinear current injection is described. Logic circuits have been experimentally tested and preliminary results are presented.
A new saturable absorber for the CO2 laser using doped KCl
Authors: Ahrenkiel R. K. , Figueira J. F. , Phipps C. R. , Dunlavy D. J. , Thomas S. J. , Sievers A. J.
Published: February 2003

A new class of saturable absorbers for 10-μm applications using doped alkali halides is demonstrated. For the ReO−4 molecular ion in KCl, the vibrational transition saturates like an ideal two-level system. This behavior is a result of the large anharmonic shift in the absorption spectra of the dopant ion. Saturation parameters of 1.45 MW/cm2 and a relaxation time T1 of 120 ps are measured at room temperature.
HgX (B) radiative lifetime by fast photolysis of HgX2 (X=Br,I)
Authors: Waynant R. W. , Eden J. G.
Published: February 2003

The radiative lifetimes of the HgBr(B) and HgI(B) states have been determined to be 23.7±1.5 and 27.3±2.0 ns, respectively, by fast photolysis of HgBr2 and HgI2 using e-beam-excited ArF and KrCl fluorescence. This experimental approach generated simple exponential decay curves which facilitated measurement of the lifetimes and the rate of quenching of the excited HgX (B) states by HgX2 (X=Br or I) molecules. Although the lifetimes reported here are in agreement with previous experimental measurements, they contradict a recently published theoretical calculation.
Single-longitudinal-mode cw room-temperature Ga1−xAlxAs-GaAs channel-guide lasers grown by metalorganic chemical vapor deposition
Authors: Dupuis R. D. , Dapkus P. D.
Published: February 2003

Single-longitudinal-mode operation of cw room-temperature Ga1−xAlxAs-GaAs double-heterostructure lasers grown by metalorganic chemical vapor deposition has been achieved. These lasers employ a channel-guide structure to stabilize the transverse-parallel waveguide mode. Single-mode operation is reported over a wide range of dc currents.
Experimental evidence for soft x-ray population inversion by resonant photoexcitation in multicomponent laser plasmas
Authors: Bhagavatula V. A.
Published: February 2003

High-intensity laser-plasma experiments conducted on targets consisting of carbon and magnesium indicate population inversion in Mg+10 and Mg+11 ions at wavelengths of ∼100 Å. The results indicate that soft x-ray population inversion has been achieved, for the first time, by resonant photoexcitation. By this process, intensity inversions of the hydrogenic resonance lines from n=3 and n=4 are observed at electron densities as high as 1020 cm−3.
Dichromatic switching effect in two thin-film DFB dye lasers
Authors: Matsuda A. , Iizima S.
Published: February 2003

Interaction between two thin-film DFB dye lasers which are excited simultaneously in the same film plane has been investigated. A dichromatic switching effect of one of the lasers caused by the on and off switching of the excitation of another laser has been observed and an adequate model for the effect has been discussed.
Measurement of interface-state parameters near the band edge at the Si/SiO2 interface by the conductance method
Authors: Morita M. , Tsubouchi K. , Mikoshiba N.
Published: February 2003

The interface-state parameters near the band edge at the Si/SiO2 interface were measured using the MOS conductance method with the reflection technique, extending the frequency up to 100 MHz. The double peaks were observed in the conductance-vs-frequency curves. The decrease of the capture cross section toward the band edge was found due to the overlap of the double peaks. The new peak at higher frequencies suggests the existence of new interface states, which has been overlooked so far.
Surface potential of anodized p-GaAs MOS capacitors
Authors: Meiners L. G.
Published: February 2003

Metal-oxide-semiconductor (MOS) capacitors were constructed on p-type GaAs anodized in a tartaric acid-water-glycol solution at room temperature, and capacitance-voltage measurements were made on them from the quasistatic regime to 150 MHz. The data thus obtained indicate that the zero-bias surface potential is 0.59 V, that the total surface potential excursion is limited to ∼0.45 V, and that neither flatband nor inversion were achievable. The minimum in surface-state density was ∼4×1012 cm−2 eV−1.
Thermally assisted flash annealing of silicon and germanium
Authors: Cohen R. L. , Williams J. S. , Feldman L. C. , West K. W.
Published: February 2003

The radiant energy from high-intensity xenon flash lamps can be used to anneal damage in semiconductors if the sample is moderately heated before and during the flash. The annealing takes place in air via the solid-phase epitaxy process in <50 μsec and does not alter doping profiles or result in loss of volatile species.
Observation of stratospheric ozone layer by a XeCl laser radar
Authors: Uchino Osamu , Maeda Mitsuo , Kohno Jun-ichi , Shibata Takashi , Nagasawa Chikao , Hirono Motokazu
Published: February 2003

We observed the stratospheric ozone layer by a newly designed powerful laser radar using a differential-absorption technique. A discharge-pumped XeCl excimer laser with a 308-nm wavelength was used as an emitter in this system. The observed ozone concentrations in an altitude range 16–25 km are in good agreement with those measured by radiosonde. The present system is promising for the continuous monitoring of the stratospheric ozone concentration because of the simplicity of the construction.
(SN)x-GaAs polymer-semiconductor solar cells
Authors: Cohen Marshall J. , Harris J. S.
Published: February 2003

We report the first solar cell whose junction is formed by a polymer-semiconductor interface. Open-circuit voltages, Voc≳0.7 V, have been observed on cells consisting of a thin film of polymeric sulfur-nitride, (SN)x, deposited on GaAs. This is an enhancement of more than 40% over the Voc commonly measured with metal-GaAs solar cells. Initial efforts have resulted in efficiencies ≳6% without antireflection coatings.
Single polarization optical fibers: Exposed cladding technique
Authors: Ramaswamy V. , Kaminow I. P. , Kaiser P. , French W. G.
Published: February 2003

A simple method is described for fabricating fibers with large strain birefringence starting with standard MCVD preforms. The method is illustrated using borosilicate fibers. The birefringence and polarization properties are measured in a long fiber and the birefringence is also measured using a fiber slice and polarizing microscope.
Wavelength-modulation Raman spectroscopy
Authors: Levin K. H. , Tang C. L.
Published: February 2003

The derivative Raman spectral method using an electro-optically tuned laser is shown to be highly sensitive, can pick out weak and narrow spectral features hidden in a broad fluorescence background, and, most importantly, can detect extremely small shifts in the peak relative to the linewidth of the Raman-scattered light.
Transfer and quenching rate constants for XeF(III,1/2) and XeF(II,3/2)
Authors: Brashears H. C. , Setser D. W.
Published: February 2003

Rate constants for transfer between XeF(III,1/2) and XeF(II,3/2) states and quenching of XeF(III,1/2) have been measured using a method which employs the steady-state photolysis of XeF2. For He, Ne, Ar, Kr, N2, CF4, and SF6 transfer dominates over quenching; for Xe, NF3, CF3Cl, and CF3H quenching and transfer are competitive. Only for F2 is quenching dominant. Based upon the relative emission intensities from XeF(III,1/2) and XeF(II,3/2) at high pressures of buffer gases, XeF(II,3/2) must be 0.08 eV lower in energy than XeF(III,1/2).
Oxidation of sputtered molybdenum silicide thin films
Authors: Inoue Tomoyasu , Koike Katsuo
Published: February 2003

An Auger in-depth analysis and a 350 keV He+ backscattering technique were used to investigate the growth of an SiO2 protective layer and the compositional change in sputtered molybdenum silicide films after oxidation, respectively. Silicon depletion and molybdenum pileup in molybdenum silicide were observed near the SiO2/Mo-Si interface. The film becomes molybdenum rich with increasing oxidation time. The Si/Mo atomic ratio decreases rapidly in the first 30-min period and then decreases slowly, nearly proportionally to the square root of the oxidation time. These behaviors are explained by the preferential oxidation of silicon and the reduced silicon present at the SiO2/Mo-Si interface from the rest of the molybdenum silicide layer.
Intense electron-beam pinch formation and propagation in rod pinch diodes
Authors: Mahaffey R. A. , Golden J. , Goldstein Shyke A. , Cooperstein G.
Published: February 2003

Intense electron-beam pinches are formed and propagated at relatively high impedance (5–25 Ω) using rod pinch diodes. Pinch propagation of up to 20 cm with 45% efficiency and ion-generation efficiency ≳15% has been observed.
A computer simulation of laser annealing silicon at 1.06 μm
Authors: Schultz J. C. , Collins R. J.
Published: February 2003

A computer simulation of laser annealing ion-implanted silicon with 1.06-μm radiation at energy densities of 38–76 MW/cm2 shows that the amorphous surface layer of the silicon melts. Quantitative predictions for the depth of the molten zone and the impurity distribution as a function of peak laser intensity and pulse duration agree well with published experimental observations. Additional analysis indicated that pulse duration, peak power density, and the impurity implantation depth are of primary importance in controlling the laser annealing process. Also, step junctions may be produced for optimal values of these parameters.
Beryllium-ion implantation in InP and In1−xGaxAsyP1−y
Authors: Donnelly J. P. , Armiento C. A.
Published: February 2003

Anneal temperatures ⩾700 °C are necessary to obtain maximum electrical activation of implanted Be in InP. At these temperatures, activation ≳50% is generally achievable. Both the implant temperature and implanted-Be concentration affect p-n junction depth and presumably, therefore, the in-diffusion of implanted Be. For room-temperature implants, the maximum Be concentration which showed insignificant in-diffusion was 3×1018 cm−3. Using a multienergy implant schedule (highest energy 400 keV), which results in a flat as-implanted Be concentration of ≈3×1018 cm−3, sheet hole concentrations as high as 2.2×1014 and 1.5×1014 cm−2 have been obtained in InP and In0.75Ga0.25As0.52P0.48, respectively.
Planar sandwich antennas for submillimeter applications
Authors: Hwang Tien-Lai , Rutledge D. B. , Schwarz S. E.
Published: February 2003

A planar receiving antenna with a predictable pattern at submillimeter wavelength is demonstrated experimentally for the first time. It is single lobed and efficient, with a gain of approximately 8 dB at a wavelength of 119 μm.