bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies of an 80-J KrF oscillator at excitation rates of 2–7 MW/cm3
Authors: Tisone G. C. , Patterson E. L. , Rice J. K.
Published: February 2003

We have examined the performance of a 2-liter KrF oscillator pumped by a high-intensity electron beam. For input pump rates of 7 MW/cm3, up to 80 J of laser energy is extracted from the cavity in 50 ns with an efficiency (laser energy divided by deposited electron-beam energy) of 11%. Values of the small-signal-gain length product g0L, the absorption length product αL, and the saturation intensity Is were determined to be 6–16, 0.3–0.6, and 1–10 MW/cm2, respectively.
High-resolution scanning electron-beam annealing of ion-implanted silicon
Authors: Ratnakumar K. N. , Pease R. F. W. , Bartelink D. J. , Johnson N. M. , Meindl J. D.
Published: February 2003

A commercial scanning electron microscope, modified for high-current operation, has been successfully used to anneal silicon layers driven amorphous by high doses of implanted arsenic. Selected-area electron channeling patterns indicate complete recrystallization of the implanted layer with substrate orientation. Spreading-resistance measurements reveal complete electrical activation of the implanted arsenic with no dopant redistribution. The potential for localized annealing through a focused scanning electron beam is illustrated by the fabrication of submicron islands of recrystallized silicon surrounded by amorphous silicon of very high resistivity.
Casting of dendritic Cu-Nb alloys for superconducting wire
Authors: Verhoeven J. D. , Schmidt F. A. , Gibson E. D. , Ostenson J. E. , Finnemore D. K.
Published: February 2003

Consumable electrode-arc-casting techniques have been developed for the preparation of large billets of dendritic Cu-Nb alloys which are suitable for the fabrication of multifilamentary superconducting wire. The dendrite structure is somewhat more coarse than chill cast material but metallographic and chemical analyses show acceptably small radial and longitudinal segregation. The billets can be drawn to wire with no intermediate anneals. Both external diffusion after tin plating and internal diffusion of wire with a tin core can be used to transform the Nb filaments to Nb3Sn. The arc cast wire displays Jc values equivalent to previously reported values on in situ wire at high fields, but somewhat lower values at low fields.
On the elimination of Kirkendall voids in superconducting composites
Authors: Cogan S. , Holmes D. S. , Rose R. M.
Published: February 2003

Kirkendall void formation, which has hitherto prevented the use of the external diffusion technique for the manufacture of practical multifilamentary superconducting composites, can be suppressed by using solution anneals to eliminate sites for heterogeneous void nucleation.
A comparison of the behaviors of tungsten trioxide and anodic iridium oxide film electrochromics in a nonaqueous acidic medium
Authors: Rice C. E.
Published: February 2003

The performance of anodic iridium oxide film (AIROF) and WO3 electrochromic electrodes was tested in a water-free perchloric acid/dimethylsulfoxide solution. WO3 could be colored and bleached electrochemically to nearly the same extent as in water solutions, albeit much more slowly. By contrast, no electrochromic effect could be produced with AIROF electrodes. This proves that the electrochromic processes for these two materials are fundamentally different and that a simple proton-electron injection mechanism cannot account for AIROF electrochromism.
Optimization of a multistage thermoelectric refrigerator using the asymptotic temperature distribution
Authors: Weissman Y.
Published: February 2003

In this letter we suggest that the interstage temperatures which optimize the coefficient of performance of a multistage thermoelectric refrigerator can be obtained from the asymptotic temperature distribution. This temperature distribution is derived by variation calculus in the limit of infinite number of stages. Numerical calculations show that the accuracy of this method is sufficient for practical purposes. The only limitation on the temperature dependence of the thermoelectric properties of the material is the average parameter approximation.
Improved geometry for polarization-sensitive nonlinear spectroscopy
Authors: Scarparo M. A. F. , Song J. J. , Lee J. H. , Cromer C. , Levenson M. D.
Published: February 2003

An improved geometry for nonlinear spectroscopy experiments is proposed and demonstrated with the Raman-induced Kerr effect. The new scheme utilizes the nonreciprocal rotation of linearly polarized light in a Faraday rotator to manipulate the pump, probe, and signal beams. Complete collinear overlap of the interacting laser beams is conveniently achieved, with 100% of the nonlinearly generated signal incident on the detector. The sensitivity is consequently maximized.
Highly efficient (GaAl)As buried-heterostructure lasers with buried optical guide
Authors: Chinone N. , Saito K. , Ito R. , Aiki K. , Shige N.
Published: February 2003

A new buried-heterostructure laser with a buried optical guide has been developed. A threshold current around 20 mA and a differential quantum efficiency as high as 85% are obtained under cw operation. This results in highly efficient laser operation, i.e., 35% power conversion efficiency at an optical output of 15 mW per facet, at which no degradation is observed over 3000 h at room temperature. Stable lowest-order transverse mode and nearly isotropic laser beam (∼25°×35°) are obtained. Second-order harmonic distortion is 55–65 dB below the fundamental level for 30% modulation with a 100-MHz sinusoidal signal at 5 mW.
Dependence of spontaneous magnetic fields in laser produced plasmas on target size and structure
Authors: Raven A. , Rumsby P. T. , Stamper J. A. , Willi O. , Illingworth R. , Thareja R.
Published: February 2003

Faraday rotation observations of magnetic fields generated by a high-power (λ=1.06 μm) laser focused on various targets have been made. Results indicate that the fields produced on spherical targets may depend strongly on the target capacitance. Strongly structured fields were observed using large prepulse-formed plasmas on wire targets. Using novel composition discontinuity targets and a UV probe beam, planar magnetic fields were noted and toroidal fields in the critical density region measured.
Direct injection readout of the p-n PbS-Si heterojunction detector
Authors: Steckl A. J. , Tam K. Y. , Motamedi M. E.
Published: February 2003

An n-channel MOSFET circuit implemented within a CMOS structure has been used to test the feasibility of integrating the infrared signal readout within a PbS-Si heterojunction detector (HJD) array. The efficiency of the source-coupled direct injection readout was determined from ηinj=I′ph/Iph, where I′ph is the photocurrent measured with the direct injection readout and Iph is the photocurrent measured with a virtual ground transimpedance amplifier. From the equivalent circuit of the direct injection input, the theoretical injection efficiency at low frequency has been shown to be ηinj =gm(gm+GD)−1, where gmis the MOSFET transconductance and GD is the detector conductance. Good agreement between the experimental and theoretical injection efficiency has been found over a wide range. Injection efficiencies as high as 90% have been measured.
Highly doped evaporated amorphous silicon by alkali implantation
Authors: Beyer W. , Barna A. , Wagner H.
Published: February 2003

Evaporated films of amorphous silicon can be doped interstitially by implantation of alkali ions. Room temperature conductivity values as high as σ=2×10−3 (Ω cm)−1 and activation energies of σ as low as 0.25 eV are obtained by implantation of 1% potassium in films prepared with a low rate of deposition. The doped state is stable up to 320 °C. Results from stepwise doping with sodium indicate a rather constant density of localized states in the gap of the order 3×1019/cm3 eV for rapidly evaporated films.
Low-loss reflection-star couplers for optical-fiber distribution systems
Authors: Johnson D. C. , Kawasaki B. S. , Hill K. O.
Published: February 2003

Low-loss reflection-star couplers using fused biconically tapered fiber loops are described. The fabrication technique is simple and also allows the construction of hybrid reflection-transmission-star couplers.
Cadmium-tin oxide films deposited by rf sputtering from a CdO-SnO2 target
Authors: Miyata N. , Miyake K. , Fukushima T. , Koga K.
Published: February 2003

Cadmium-tin oxide (CTO) films with high conductivity and high transparency were prepared by rf sputtering from a CdO-SnO2 target in an Ar or Ar-O2 atmosphere. The resistivity of CTO films was 6.5×10−4 Ω  in the film thickness range of 2500–15000 Å, and the average transmission was 90% over the visible region.
Fabrication of mesa-type waveguides in AlGaAs structures by laser irradiation
Authors: Salathé R. P. , Gilgen H. H. , Rytz-Froidevaux Y. , Lüthy W. , Weber H. P.
Published: February 2003

Passive three-dimensional light guides have been generated by exposing small areas of AlxGa1−xAs heterostructure material to cw argon laser radiation and subsequent removal of the irradiated zones by selective etching. Mesa-type waveguides with a width of 2.5 μm and a lateral definition of better than 0.3 μm have been produced. The luminescence emitted by the samples during the irradiation has been monitored to investigate the dynamics of processing.
(InGa)(AsP)/InP embedded mesa stripe lasers
Authors: Prince F. C. , Patel N. B. , Bull D. J.
Published: February 2003

A structure to avoid nonlinearities in the light-output versus current is proposed in long wavelength lasers of InGaAsP. This structure is very similar to a channeled-substrate planar laser in GaAlAs system. As in the GaAs lasers, nonlinearities are significantly reduced by introducing a built-in passive wave-guiding mechanism.
A new InGaAsP/InP dual-wavelength LED
Authors: Sakai Shiro , Aoki Takahiro , Amemiya Yoshifumi , Umeno Masayoshi
Published: February 2003

A new dual-wavelength light-emitting diode (LED) emitting near 1.2 and 1.3 μm has been fabricated. The differential efficiencies of the two outputs were 0.36 and 0.88%, respectively. The intensities of these optical outputs can be controlled independently. The optical cross talk between the two wavelengths was −10 and −16 dB at 1.15 and 1.35 μm, respectively. This device is useful for wavelength-multiplexed optical communication systems.
Hall effect in reactively sputtered Cu2S
Authors: Leong John Y. , Yee Jick H.
Published: February 2003

The Hall effect in thin films of reactively sputtered Cu2S was measured at temperatures from 90 to 300 °K. The hole concentration ranged from 1018 to 2×1019 cm−3. The hole mobility ranged from 5.5 to 9 cm2/V s. The predominant scattering mechanisms are ionized impurity scattering at T<100 °K and optical phonon scattering at T≳100 °K.
Vapor-phase epitaxial InxGa1−xAs on (100), (111)A, and (111)B InP substrates
Authors: Kanbe Hiroshi , Yamauchi Yoshiharu , Susa Nobuhiko
Published: February 2003

Effects of InP substrate orientation on InxGa1−xAs vapor-phase epitaxial growth are studied. The fractional composition x of the grown layer on (100) substrate is smaller than for (111) B at identical growth temperatures and gas flow rates. The In content x decreases with increasing temperature. Growth rate, carrier concentration, and carrier mobility depend on substrate orientation. Growth on (100) substrates at temperatures above 710°C is suitable for obtaining smooth surface layers with low carrier concentration and high mobility.
Methods for minimizing silicon regrowth in aluminum films
Authors: Learn Arthur J. , Nowicki R. S.
Published: February 2003

The transport of polycrystalline silicon into an overlying aluminum film and silicon regrowth in the metal medium under heating at 500 °C was examined as a function of doping level and grain size of the silicon. Such regrowth was eliminated through phosphorus doping and was substantially reduced for increased grain size. These results are consistent with a mechanism of silicon grain-boundary transport in the films. The necessity for a silicon oxide layer at the aluminum-silicon interface, if regrowth is to occur, is also indicated.
Alloying of Au layers and redistribution of Cr in GaAs
Authors: Magee T. J. , Peng J. , Hong J. D. , Deline V. R. , Evans C. A.
Published: February 2003

Alloying of Au films on Cr-doped GaAs substrates and Sn-doped LPE layers grown on semi-insulating substrates has been investigated by TEM and SIMS profiling. Annealing at 350 °C for variable periods was found to produce rapid outdiffusion of Cr into regions of near-surface damage induced by strain effects at the interface and subsequent diffusion of Au into the GaAs.
Substrate temperature limits for epitaxy of InP by MBE
Authors: Norris M. T. , Stanley C. R.
Published: February 2003

The temperature range within which epitaxial unintentionally doped InP can be deposited from In and P2 beams by MBE on to (100) InP substrates has been determined to be 100–405 °C. Above 410 °C whisker growth from In droplets via a vapor-liquid-solid process occurs; below 95 °C polycrystalline layers result on account of the nondissociation of P2.
cw Ar+ laser annealing of optically active impurities in nitrogen-implanted AlxGa1−xAs (x=0.58)
Authors: Makita Yunosuke , Yokota Masaki , Nojiri Hidetoshi , Tsurushima Toshio , Tanoue Hisao , Kanayama Toshihiko , Shimada Jun-ichi
Published: February 2003

Laser annealing of nitrogen implanted AlxGa1−xAs was carried out by using an Ar+ laser. A reliable and well-controlled annealing was performed with threshold power density of the order of 105 W/cm2. Photoluminescence (PL) characteristics show that laser annealing is superior to thermal annealing in terms of PL intensities and the absence of deep levels. New emission bands were obtained at the intermediate power density of the laser, which were never obtained in thermal annealing.
Carrier recombination through donors/acceptors in heavily doped silicon
Authors: Hu Chenming , Oldham William G.
Published: February 2003

Carrier recombination in heavily doped semiconductors via shallow donor or acceptor states is analyzed. The results are in general agreement with experimental lifetime observations including the 1/n20 or 1/P20 dependence, and the insensitivity to temperature and to the dopant used. Capture cross sections of about 10−20 cm2 needed to fit the lifetime data are reasonable for neutral traps and are consistent with low-temperature capture cross sections reported for shallow dopants.
Measurement of the input impedance of a RF biased SQUID
Authors: Bordoni F. , Carelli P. , Modena I. , Romani G. L.
Published: February 2003

An experimental method to measure the imaginary and real part of the input impedance of an rf biased SQUID is described. The experimental results are in good agreement with the predictions of a detailed theoretical model of the rf SQUID, recently published. In particular it seems confirmed that the real part of the input impedance has a negative value which depends on the square of the input signal frequency. This effect must be taken into account whenever a SQUID is used to measure high frequency signals.
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u multifilamentary superconducting wires fabricated using a controlled high-temperature gradient
Authors: Fihey J. L. , Neff M. , Roberge R. , Flemings M. C. , Foner S. , Schwartz B. B.
Published: February 2003

A 0.64-cm-diam. Cu-Nb composite rod was continuously melted at 1800 °C, then resolidified in a controlled large temperature gradient (∼ 400 °C/cm) to produce a microstructure of aligned [directionally solidified, (DS)] dendrites in a copper matrix. Primary dendrite arm sizes of ∼50, 20, and 10 μm were measured for growth rates of 5.6×10−4, 1.7×10−2, and 0.11 cm/sec, respectively. Higher growth rates produced an equiaxed structure typical of chill casting. After processing, the overall Jc of the DS wires and the effect of stress on Jc were comparable to those of chill-cast specimens. The atomic fraction of Nb converted to Nb3Sn increased with decreasing filament size, and Tc was approximately 17.6 K for the DS alloys.
Near-equilibrium LPE growth of low threshold current density In1−xGaxAsyP1−y(λ=1.35 μm) DH lasers
Authors: Nelson R. J.
Published: February 2003

The growth of In1−xGaxAsyP1−y double heterostructure (DH) laser material by liquid phase epitaxy (LPE) under near-equilibrium growth conditions which produce small growth rates is described. Broad-area threshold current densities for this material are as low as 670 A/cm2 for 0.1-μm active layers which is the lowest value yet reported for this material system. This value is comparable with the best reported value for LPE Ga1−xAlxAs with a similar refractive index step. For comparison, material grown at higher growth rates using the commonly employed two-phase and supercooling techniques are found to give consistently higher threshold current densities than those grown under near-equilibrium conditions in the same LPE system. The spontaneous luminescence observed in window lasers grown by the near-equilibrium method appears uniform with no evidence of dark absorbing regions which could cause self-pulsations in the laser output during initial operation.
Electroluminescence in reverse-biased ZnS:Mn Schottky diodes
Authors: Gordon N. T. , Ryal M. D. , Allen J. W.
Published: February 2003

Electroluminescence in reverse-biased ZnS:Mn Schottky diodes is reported. The characteristics are similar to those ZnSe:Mn LEDS’s described previously. Light emission results from the impact excitation of manganese luminescent centres by hot electrons in the depletion region. The characteristic field for impact excitation is 8×105 V cm−1.
Implantation of shallow impurities in Cr-doped semi-insulating GaAs
Authors: Favennec P. N. , L’Haridon H.
Published: February 2003

Zinc and selenium implantations have been performed in Cr-doped semi-insulating GaAs. We show that all zinc and selenium implanted impurities are electrically active after annealing at 900 °C. But, in addition to the implantation distribution, there is a distribution induced by the chromium outdiffusion during annealing leading to a Cr-depleted zone, which can become conductive. By taking into account these distributions, the electrical measurements may be explained.
Self-diffusion in silicon as probed by the ( p,γ) resonance broadening method
Authors: Hirvonen J. , Anttila A.
Published: February 2003

The self-diffusion preexponential factor D0=8.0 cm2/s and activation energy Q=4.1 eV for intrinsic silicon have been determined with the ( p,γ) resonance broadening method in the temperature region 900–1100 °C, in a first application of this method to self-diffusion measurements. Its suitability was tested by extending the self-diffusion measurements to lower temperatures than those performed with other methods.
High-speed InP optoelectronic switch
Authors: Leonberger F. J. , Moulton P. F.
Published: February 2003

The successful fabrication and demonstration of an InP optoelectronic switch is reported. The results obtained suggest that this device may be better suited for high-speed analog signal processing applications than previously reported Si and GaAs switches. In experiments using cw mode-locked lasers, the switches have exhibited an on-state impedance of 45 Ω for 40pJ of incident laser energy and an inherent rise time of 30 psec. In addition, the switches have been used to generate a train of 70-psec-wide pulses at a 900-MHz repetition rate, and to sample a 68.9-MHz sine wave at 275 MS/sec with an accuracy to 0.2 dB (98%) and an on-off ratio of 40 dB.
An amorphous silicon photodetector for picosecond pulses
Authors: Auston D. H. , Lavallard P. , Sol N. , Kaplan D.
Published: February 2003

A new photoconductive detector utilizing an amorphous silicon film grown by CVD is demonstrated to have a response time of 40 ps. An estimate of the carrier mobility suggests a mechanism involving the rapid relaxation of photoexcited carriers from relatively mobile extended states to immobile localized states.
Comparison of ion optics for transverse slot and cylinders
Authors: Whealton J. H. , McGaffey R. W. , Jaeger E. F.
Published: February 2003

A theoretical comparison of ion optics for transverse slot and cylinders was performed with an algorithm that accurately computes the two-dimensional collisionless sheath. An aberration-dominated optics situation, typical of many neutral injectors used for fusion research, was analyzed. The slot geometry produced a minimum beam rms divergence of 3.1°, while the cylinder geometry produced a divergence of 1.8° (in agreement with experiment). We present evidence to delineate the cause for this effect.
Dry development of Se-Ge inorganic photoresist
Authors: Yoshikawa Akira , Ochi Osamu , Mizushima Yoshihiko
Published: February 2003

Striking rate differences in gaseous plasma etching is found between undoped and Ag-photodoped Se-Ge inorganic photoresist. After the Ag photodoping, the plasma etch rate almost disappears and the etch rate ratio reaches 370:1. This leads to the ’’dry development’’ of the Se-Ge inorganic resists. It is shown that by using the plasma etching technique, fine pattern delineation of less than 1-μm linewidth is easily possible. Several advantages over wet chemical processing are expected in process simplification and reproducibility.
Very low current threshold GaAs-AlxGa1−xAs double-heterostructure lasers grown by molecular beam epitaxy
Authors: Tsang W. T. , Reinhart F. K. , Ditzenberger J. A.
Published: February 2003

GaAs-AlxGa1−xAs (x=0.3) double-heterostructure (DH) lasers having very low current threshold densities have been prepared by molecular beam epitaxy (MBE). For DH lasers having Al-mole-fraction differences between the active layers and AlxGa1−xAs confinement layers Δx∼0.3, the best of the MBE-grown DH laser wafers have averaged current threshold densities similar to those obtained from the best of similar-geometry DH lasers prepared by liquid-phase epitaxy (LPE) and by metalorganic chemical vapor deposition (MO-CVD). With Δx=0.3, the lowest averaged current threshold density achieved is 800 A/cm2 (without reflective coating) for a wafer with an active layer thickness of 0.15 μm.
High-power constricted double-heterojunction AlGaAs diode lasers for optical recording
Authors: Botez D. , Spong F. W. , Ettenberg M.
Published: February 2003

In this letter we describe a new type of constricted double-heterojunction injection laser especially designed for optical disk recording. The laser is capable of steady operation in a stable fundamental spatial mode at powers of 80 mW/facet at 20% duty cycle (25-MHz repetition rate, 8-nsec-wide pulses) and 50 mW/facet at 50% duty cycle (10-MHz repetition rate, 50-nsec-wide pulses). Such devices have been used in high-data-rate optical recording and preliminary results indicate operating life in excess of 103 h at 40 mW/facet and 50% duty cycle. The laser employs a very thin active region (500–800 Å) and a nearly planar structure to provide as large a source size as possible while remaining in fundamental spatial mode operation. Single longitudinal mode cw operationwas recorded up to 21 mW/facet. It is also found that an antireflection coating on the emitting facet not only raises the overall efficiency and facet damage limit, but also can simplify the modal pattern.
Attenuation of a parabolic-index fiber with periodic bends
Authors: Fields J. N.
Published: February 2003

We have measured the excess loss induced by periodic distortions of a multimode optical fiber having parabolic index profile. Agreement with theory is dramatic: the attenuation as a function of distortion wavelength exhibits a well-defined peak, characteristic of a coherent mode-coupling process in a system having uniform mode spacings. Results from measurements on step-index fibers are also presented and are shown to be in qualitative agreement with theory.
Broadband efficient thin-film Sezawa wave interdigital transducers
Authors: Bowers J. E. , Khuri-Yakub B. T. , Kino G. S.
Published: February 2003

The phase velocities and coupling coefficients for Sezawa waves in (001) ZnO on (001) cut, (100) prop. Si and on (111) cut, (112̄) prop. Si are presented. Experimental results from Sezawa wave delay lines are presented which represent for the first time bandwidths in excess of 30 MHz in a thin-film monolithic device.
Subsurface imaging with photoacoustics
Authors: Busse G. , Rosencwaig Allan
Published: February 2003

We have performed thermal-wave imaging of subsurface features in a metal using, for the first time, piezoelectric detection. Photoacoustic magnitude and phase images are presented.
Continuous series of metastable Ag-Cu solid solutions formed by ion-beam mixing
Authors: Tsaur B. Y. , Lau S. S. , Mayer J. W.
Published: February 2003

Metastable Ag-Cu solid solutions have been formed by ion-beam mixing of thin deposited Ag and Cu layers of various compositions. X-ray diffraction measurements indicated that the lattice parameters of the ion-induced Ag-Cu alloys vary almost linearly with composition, with a slight positive deviation from Vegard’s law for ideal solid solutions. The microstructures of the alloyed layers were studied by transmission electron microscopy and their stability was examined by thermal annealing up to 250 °C. The present results are compared with those obtained previously by rapid quenching techniques.
Depth resolution degradation of sputter-profiled InP/InxGa1−xAsyP1−y interfaces caused by cone formation
Authors: Williams R. S. , Nelson R. J. , Schlier A. R.
Published: February 2003

Both InP and InxGa1−xAsyP1−y surfaces with trace metal contaminations are unstable with respect to cone formation when sputter etched by Ar+. Such gross surface texture severely degrades the depth resolution of sputter profiling techniques. Cone formation can be prevented by avoiding contamination of the material being profiled with metals sputtered from various surfaces in the analysis system. An uncorrected width of 140 Å was determined using techniques which optimize sputter depth profiling for an In0.74Ga0.26As0.60P0.40-InP heterojunction grown by liquid phase epitaxy.
A low-beam-divergence cw (GaAl)As double-heterostructure laser grown by low-pressure metallorganic chemical vapor deposition process
Authors: Hirtz J. P. , Bui-Dinh-Vuong  , Duchemin J. P. , Hirtz P. , de Cremoux B. , Bisaro R. , Merenda P. , Bonnet M. , Duda E. , Mesquida G. , Carballes J. C.
Published: February 2003

We report the operation of a new stripe geometry (GaAl)As double-heterostructure laser, grown by low-pressure metallorganic vapor deposition (MO-CVD). Several points make this MO-CVD laser very suitable for optical communication: (i) a very low beam divergence in the direction perpendicular to the junction plane, 26 °; (ii) a low pulsed threshold current, 80 mA (stripe geometry: 5×300 μm); (iii) an emission wavelength of 8300 Å (optimum for optical fiber transmission).
Chromium redistribution during thermal annealing of semi-insulating GaAs as a function of encapsulant and implant fluence
Authors: Vasudev P. K. , Wilson R. G. , Evans C. A.
Published: February 2003

Chromium depth distributions have been measured in semi-insulating GaAs substrates that were thermally annealed (840 °C, 20 min) under both capless and SiO2-encapsulated conditions, with and without the presence of sulfur implants of several fluences. It is clearly shown that the chromium redistribution is not strongly influenced by the encapsulant but depends on the background chromium level and the implantation-induced damage. For sulfur implant fluences below ∼1013 cm−2, the chromium redistribution is similar to that in an annealed, unimplanted substrate.
Electrochemical light-emitting diodes
Authors: Butler M. A. , Ginley D. S.
Published: February 2003

Luminescence has been observed at a p-GaP/electrolyte interface in several different electrolytes. A new mechanism, direct injection of ions into the semiconductor surface, is shown to be responsible for the luminescence. Experimental results for the luminescence spectral response, current dependence, time dependence, and ion dependence will be presented. Elastic recoil detection experiments have directly observed the injected ions.
Processing dependence of metal/tunnel-oxide/silicon junctions
Authors: Dressendorfer P. V. , Lai S. K. , Barker R. C. , Ma T. P.
Published: February 2003

The effects of process variations on the fixed-charge density, interface-state density, and tunneling properties of tunnel oxides on (100) silicon are discussed. Annealing the oxide in nitrogen reduces the fixed-charge and interface-state densities substantially, but also causes a marked increase in oxide capacitance. Anneals in forming gas before metallization alter the interface-state distribution and decrease the insulating qualities of the tunneling oxides. Postmetallization anneals in forming gas reduce the interface-state density to 1×1011 cm−2 eV−1 or below, and appear not to affect the current through the oxide. No evidence for metal-induced interface states is observed.
Photoacoustic detection of ferromagnetic resonance in films
Authors: Evora C. , Landers R. , Vargas H.
Published: February 2003

We report on the detection of the ferromagnetic resonance of Ni and Fe films through the photoacoustic effect. The photoacoustic signal dependence on both the magnetic field and the chopping frequency is also discussed in light of existing theoretical models for the production of the photoacoustic signals.
Effect of structure and impurities on the epitaxial regrowth of amorphous silicon
Authors: Foti G. , Bean J. C. , Poate J. M. , Magee C. W.
Published: February 2003

The regrowth of ultrahigh-vacuum-deposited amorphous silicon occurs along a planar interface which moves outward from the crystalline substrate at a nonlinear rate. Secondary ion mass spectroscopy indicates that atmospheric gases percolate into the films upon exposure to air. Of the entrapped gases, the oxygen content at a given depth correlates particularly well with the regrowth rate at that point. Extrapolation to zero oxygen content shows that deposited and implanted amorphous silicon have significantly different intrinsic regrowth rates. This difference suggests that these materials have a fundamentally different structure.
Direct optical visibility of ferroelectric domains of dicalcium strontium propionate, Ca2Sr(C2H5CO2)6
Authors: Hosokawa T. , Kobayashi J. , Uesu Y.
Published: February 2003

It has been found that antiparallel domains in a ferroelectric phase of Ca2Sr(C2H5CO2)6 are visible in polarized light traveling along the unique optic axis, although the phase is optically uniaxial. The domains with opposite polarity are discerned as pseudo-octagonal islands with dark and bright contrast. As the most probable origin of the visibility the induced dissymmetry due to growth pyramids is proposed.
Graded-index antireflection surfaces for high-power laser applications
Authors: Lowdermilk W. H. , Milam D.
Published: February 2003

Graded-index antireflection (AR) surfaces can be developed on phase-separated optical-quality glass. These surfaces have a median damage threshold of 12 J/cm2 for 1-ns, 1.06-μm laser pulses which is 2.5 times higher than the threshold of thin-film AR coatings, and reflectivity ≲0.2%, comparable to thin-film coatings.
InP surface conducting films from electron-pulse annealing
Authors: Davies D. Eirug , Kennedy E. F. , Comer J. J. , Lorenzo J. P.
Published: February 2003

Heavily conducting layers have been observed in InP subjected to pulse electron beam annealing. No implantation is involved and sheet resistivities of ∼10 Ω/⧠ are typically obtained. The conduction is confined to within ∼500 Å of the surface and is annealable thermally ∼400 °C. Indicated concentrations are ≳1021 cm−3. Both electron microscopy and Rutherford backscattering show that electron beam annealing leads to a phosphorus loss at the surface. It is presumed that the observed conduction can be attributed to some defect associated with phosphorus loss.
Photoemission measurements of interface barrier energies for tunnel oxides on silicon
Authors: Dressendorfer P. V. , Barker R. C.
Published: February 2003

Internal photoemission measurements of the Si/SiO2 and Al/SiO2 barrier heights on oxides of tunneling thickness (43–56 Å) are compared with measurements on thick oxides (310 Å and greater) and the barrier heights are found to be the same. The results suggest that substantially thinner oxides, grown by the same method, can be characterized by the same barrier heights. Limits to the experimental technique posed by photovoltaic and displacement currents, and transport of hot carriers in the tunnel oxide are discussed.
Hydrogen-ion bombardment of GaAs
Authors: Steeples K. , Dearnaley G. , Stoneham A. M.
Published: February 2003

Gallium arsenide has been subjected to bombardment by protons, deuterons, and tritons, and the electrical carrier-removal effects have been investigated. Deuteron bombardment gives vastly more efficient carrier removal than either proton or triton bombardment, and with better thermal stability. A model, based upon nonradiative recombination-enhanced defect reactions, is presented to explain this effect.
Anomalous stress in thermal oxide of polycrystalline Si
Authors: Shintani A. , Nakashima H.
Published: February 2003

The thermal oxide of polycrystalline Si (poly-Si oxide) is found to be under a compressive stress two or more times larger than the stress in the thermal oxide of single-crystalline Si (single-Si oxide). The stress in poly-Si oxide depends largely on poly-Si growth temperature, oxidation temperature, and oxide thickness, especially for oxides less than 200 nm thick. The surface valleys formed at poly-Si grain boundaries relate to this phenomena. The behavior of stress variations with oxide thickness is not substantially affected by oxidation temperature. The temperature dependence (room temperature to 800 °C) of stress in poly-Si oxide is similar to that in single-Si oxide. Consequently, the large stress generation in poly-Si oxide is not due to oxide characteristics but to poly-Si surface morphological conditions.
Incorporation of boron during the growth of GaAs single crystals
Authors: Hopkins C. G. , Deline V. R. , Blattner R. J. , Evans C. A. , Magee T. J.
Published: February 2003

A study of GaAs prepared by conventional Bridgman techniques and by liquid-encapsulated Czochralski methods reveals that only small amounts of boron are incorporated from the boric oxide encapsulant. When a pyrolytic boron nitride crucible is used, there is a 100-fold increase in the amount of incorporated boron, suggesting some decomposition of the boron nitride.
Nuclear-pumped cw lasing of the 3He-Ne system
Authors: Carter B. D. , Rowe M. J. , Schneider R. T.
Published: February 2003

The gain for the 6328-Å laser line for the nuclear excited He-Ne system has been measured for 300 Torr pressure at thermal neutron flux levels from 2×107 to 1×1014 n/cm2 sec. In order to estimate small:signal gain, the gain was also measured as a function of input intensity. For demonstration of feasibility of cw operation of nuclear pumped lasers, a cavity was operated and lasing was observed. Although the laser output was small, we conclude that lasing in a cw mode has been achieved with He-Ne using moderate neutron flux levels.
The effect of substrate temperature on the current threshold of GaAs-AlxGa1−xAs double-heterostructure lasers grown by molecular beam epitaxy
Authors: Tsang W. T. , Reinhart F. K. , Ditzenberger J. A.
Published: February 2003

The current threshold densities (Jth) of broad-area double-heterostructure (DH) lasers, the photoluminescence (PL) intensities of the p-GaAs cap layers, P-AlxGa1−xAs (x∼0.3) confinement layers, and the GaAs active layers of the DH wafers are investigated as a function of the substrate temperature (450–650 °C) during MBE growth. The PL intensities of the P-AlxGa1−xAs (x∼0.3) confinement layers and the GaAs active layers increase and the Jth’s of the DH lasers decrease with increasing substrate temperature. The improvement of Jth with increasing substrate temperature is found to be well correlated to the improvement of the optical qualities of the AlxGa1−xAs layers with increasing substrate temperature. However, the PL intensities of the p-GaAs cap layers are relatively independent of substrate temperature.
Transverse mode stabilized AlGaAs/GaAs plano-convex waveguide laser made by a single-step liquid phase epitaxy
Authors: Ide Y. , Furuse T. , Sakuma I. , Nishida K.
Published: February 2003

A new laser structure, the plano-convex waveguide (PCW) laser is described. A thickness-varied waveguide layer used for transverse mode stabilization was formed adjacent to the planar active layer. The laser structure was fabricated by a single-step liquid phase epitaxial growth on a grooved substrate. With pulsed injection, stable fundamental transverse mode operation was observed up to 3.5 times threshold current, where power output was 36 mW/facet. At zero dc bias, single longitudinal mode was attained after 10 ns of the leading edge of the optical pulse. Far-field beam divergences of about 10° and 50° were obtained in directions parallel and perpendicular to the junction plane, respectively.
Pulsed CO2 laser interaction with a metal surface at oblique incidence
Authors: McKay J. A. , Schriempf J. T. , Cronburg T. L. , Eninger J. E. , Woodroffe J. A.
Published: February 2003

Thermal fluence deposition and surface pressure generation produced by a CO2 laser pulse (λ=10.6 μm, during 10 μs, maximum intensity 3 MW/cm2) have been measured as a function of angle of incidence ϑ on sheet aluminum in air. We find that air plasma ignition depends on the laser beam intensity I0 only, not on the surface-normal flux I0 cosϑ. Conversely, the fluence deposition and surface pressure depend only on the product I0 cosϑ, and obey the square-root and two-thirds-power dependences observed with simple I0 variation at normal incidence.
Photoacoustic measurements of ion-implanted and laser-annealed GaAs
Authors: McFarlane R. A. , Hess L. D.
Published: February 2003

Photoacoustic techniques were developed for use as a rapid and sensitive diagnostic of crystalline disorder produced by ion implantation in gallium arsenide. With a 150-keV silicon implant, doses as low as 1012 cm−2 were detectable. Recrystallization of ion-implanted gallium arsenide by laser annealing is readily detected by the photoacoustic method.
Liquid crystal alignment on surfactant treated obliquely evaporated surfaces
Authors: Heffner W. R. , Berreman D. W. , Sammon M. , Meiboom S.
Published: February 2003

We report observations on the alignment of nematic liquid crystals on surfaces of obliquely deposited silicon monoxide, with and without additional treatment with surfactant. The liquid crystals reported on are 4.4-dihexylazoxybenzene and 4-heptyl-4’-cyanobipheny. The surfactants used are N,N-dimethyl-N-octadecyl-3-aminopropyltrimethoxysilyl chloride and plasma polymerized tetrafluoroethylene. While untreated silicon monoxide surfaces produce inclined alignment, with the liquid crystal director oriented in the same quadrant as the direction of deposition, it was found that treatment with surfactant can result in an inclined alignment away from the direction of deposition, with the director now oriented nearly perpendicular to the direction obtained in the absence of surfactant. A simple model to explain these observations is presented.
A 500-MHz GaAs charge-coupled device
Authors: Deyhimy I. , Eden R. C. , Anderson R. J. , Harris J. S.
Published: February 2003

The higher electron mobility in GaAs relative to silicon makes it possible to design an ultra-high-Speed charge-coupled device. A buried-channel Schottky barrier gate GaAs charge-coupled device (CCD) is described which has been operated at up to 500 MHz clock frequency. The transit-time-limited upper clock frequency in this device is predicted to exceed 5 GHz.
Solid-phase growth of large aligned grains during scanned laser crystallization of amorphous Ge films on fused silica
Authors: Fan John C. C. , Zeiger H. J. , Gale Ronald P. , Chapman Ralph L.
Published: February 2003

Well-aligned grains of dimensions up to 2–3×100 μm have been obtained by laser crystallization of amorphous Ge films on fused-silica substrates. A theoretical model has been developed for the dynamics of the crystallization process, a solid-phase transformation that is greatly accelerated by liberation of the latent heat of transformation, resulting in either periodic or runaway motion of the crystallization front. We believe that scanning of amorphous films with an energy beam of large aspect ratio may be developed into an effective process for preparing large-grained or even single-crystal sheets of Ge and other semiconductors, including Si and GaAs.
Polycrystalline silicon films deposited in a glow discharge at temperatures below 250 °C
Authors: Iqbal Z. , Webb A. P. , Vepřek S.
Published: February 2003

Raman scattering, x-ray diffraction and electron diffraction results show that thin films of silicon (ranging in thickness from a few hundred Å to 1 μm) prepared by chemical transport in low-pressure hydrogen plasma at a temperature between 230 and 280 °C and a deposition rate of up to ∼0.5 Å sec−1, are polycrystalline. X-ray diffraction and transmission electron microscopic data indicate crystallite sizes amounting to a few hundred Å.
Leakage current in InGaAsP avalanche photodiodes
Authors: Yeats R. , Chiao S. H.
Published: February 2003

The increased leakage current in InGaAsP APD’s near breakdown is found to be a rather uniform bulk property, not associated with conventional microplasmas, dislocations, or surface effects. Surface effects were eliminated by the fabrication of guard ring APD’s, but the increased leakage current persisted. Surface effects were further ruled out by a statistical study of the leakage current in a large sample of APD’s. The study shows conclusively that the leakage current is proportional to diode area, not perimeter.
cw high-power single-mode operation of constricted double-heterojunction AlGaAs lasers with a large optical cavity
Authors: Botez Dan
Published: February 2003

A new type of constricted double-heterojunction (CDH) injection laser is presented: a single-mode laser with a large optical cavity (CDH-LOC) and leaky lateral waveguide. Single-mode cw operation (spatially and longitudinally) is achieved in a large lasing spot (1.7×6.5 μm) up to 40 mW output power (one facet) and 2.5 times above threshold. cw thresholds as low as 75 mA and external quantum efficiencies as high as 35% from one facet are obtained for diodes with reflectors on the back facet. The antiguiding nature of these devices is confirmed in the lateral far-field patterns. As opposed to positive-index lateral guiding structures, in CDH devices heating can be beneficial for single-mode selection at high powers.
Plasma sheath driven targets
Authors: Brownell John H. , Freeman Bruce L.
Published: February 2003

Plasma focus driven target implosions are simulated using hydrodynamic-burn codes. Support is given to the idea that the use of a target in a plasma focus should allow ’’impedance matching’’ between the fuel and gun, permitting larger fusion yields from a focus-target geometry than the scaling laws for a conventional plasma focus would predict.
SiO2 antireflection coating effect on cw laser annealing of ion implanted Si
Authors: Okabayashi H. , Yoshida M. , Ishida K. , Yamane T.
Published: February 2003

Annealed strip width, formed by a single line scan of Nd : YAG laser beam on SiO2/As-implanted Si structure, was found to vary with SiO2 thickness. Observed SiO2 thickness dependence of the annealed strip was in good agreement with calculation made on the basis of the SiO2 antireflection coating effect.
Characterization of surface oxides by Raman spectroscopy
Authors: Farrow R. L. , Mattern P. L. , Nagelberg A. S.
Published: February 2003

Raman spectroscopy is shown to provide direct information on the composition and structure of surface oxides formed on alloys. Previously, identification of specific compounds present in these oxides only could be inferred from conventional surface analysis methods. In our studies, backscattering spectra were obtained from thick oxide films (⪞10 μm) present on high purity and commercial stainless steels after exposure to air and coal gasifier environments at 980 °C. With as-grown oxides, data were obtained from the outer oxide regions. Spectra from inner regions also were measured using grazing-angle sectioning techniques. The presence of impurities and minor alloying constituents in the substrates are shown to have profound effect on results; for example, the addition of a few percent of titanium and manganese resulted in the formation of a duplex scale with a thin, complex, outer layer and a relatively thick α–Cr2O3 inner scale.
Application of laser annealing techniques to increase channel mobility in silicon on sapphire transistors
Authors: Yaron Giora , Hess LaVerne D.
Published: February 2003

Laser annealing techniques were successfully incorporated into standard metal-oxide-semiconductor silicon-on-sapphrie (MOS/SOS) processing to increase transistor channel mobility. Silicon islands were photolithographically defined and chemically etched (by KOH) on standard SOS wafers. The islands were exposed to radiation from an excimer laser (λ=2490 Å) having a pulse duration of 25 nsec, a beam size in the range 0.1–0.2 cm2, and an energy density in the range 0.5–1.0 J/cm2. Using standard processing techniques, MOS transistors were fabricated and characterized. It was found that MOS transistors fabricated over islands exposed to a beam having an energy density of 0.8 J/cm2 exhibit a 30% increase in channel mobility.
Monolithic integration of a GaAlAs injection laser with a Schottky-gate field effect transistor
Authors: Fukuzawa T. , Nakamura M. , Hirao M. , Kuroda T. , Umeda J.
Published: February 2003

Monolithic integration of a GaAlAs laser with a GaAs Schottky-gate field effect transistor is demonstrated. A GaAs field effect transistor with a 3-μm gate length is formed on a double-heterostructure laser crystal which is protected by a high-resistivity isolation layer. Laser light intensity is modulated to realize rise and fall times of less than 0.4 ns by modulating the field effect transistor gate voltage.
Picosecond signal processing with planar, nonlinear integrated optics
Authors: Normandin R. , Stegeman G. I.
Published: February 2003

The convolution of picosecond optical signals is demonstrated via the nonlinear mixing of guided waves in a Ti in-diffused LiNbO3 waveguide. Various applications are discussed.
Heavy-doping effects and impurity segregation during high-pressure oxidation of silicon
Authors: Fuoss Dennis , Topich James A.
Published: February 2003

Silicon samples which were ion- implanted with boron or arsenic were oxidized in high-pressure (10 atm) pyrogenic steam to determine the effects of heavy doping on the oxide growth rate. Heavy n-type doping (arsenic) was found to enhance the silicon oxidation rate, but the enhancement was not as great as for oxidation at atmospheric pressure. For p-type (boron) doping there was only slight enhancement for both high-pressure and 1-atm oxidations. Samples were then depth profiled using secondary-ion mass spectroscopy (SIMS) to observe the segregation of boron and arsenic at the Si:SiO2 interface. The effective coefficients of the impurities for high-pressure oxidation were found to deviate significantly from those for atmospheric pressure oxidation.
Be-implanted (GaAl)As stripe geometry lasers
Authors: Bar-Chaim N. , Lanir M. , Margalit S. , Ury I. , Wilt D. , Yust M. , Yariv A.
Published: February 2003

(GaAl)As double-heterostructure stripe geometry lasers have been fabricated using Be ion implantation. Pulsed threshold currents as low as 21 mA have been found. The light-vs-current characteristics were kink-free up to 10 mW output power and the measured differential quantum efficiency was 45%.