bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of an amorphous metallic hydride by reaction of hydrogen with crystalline intermetallic compounds—A new method of synthesizing metallic glasses
Authors: Yeh X. L. , Samwer K. , Johnson W. L.
Published: February 2003

Noncrystalline metallic hydrides can be formed from certain crystalline Zr3Rh intermetallic phases by hydrogenation. X-ray diffraction patterns, density measurements, and superconducting properties confirmed the transition from the crystalline to the amorphous phase by this solid state reaction. The transition can be explained in terms of a ‘‘chemical frustration’’ effect.
Initial stage of sputtering in silicon oxide
Authors: Hattori Takeo , Hisajima Yukimoto , Saito Hiroyuki , Suzuki Toshihisa , Daimon Hiroshi , Murata Yoshitada , Tsukada Masaru
Published: February 2003

The effect of argon ion bombardment on a silicon oxide film prepared on a Si(111) surface by dry oxidation was investigated by measuring partial yield spectra in addition to the oxygen induced Si 2p core level shift. The experimental observations can be understood such that the SiO2 network is decomposed at the initial stage of argon ion bombardment. In the following stage of bombardment, the silicon oxide films are sputter etched resulting in a decrease in the oxide film thickness.
High quality polysilicon by amorphous low pressure chemical vapor deposition
Authors: Harbeke G. , Krausbauer L. , Steigmeier E. F. , Widmer A. E. , Kappert H. F. , Neugebauer G.
Published: February 2003

Undoped and in situ phosphorus-doped low pressure chemical vapor deposited polysilicon films have been studied by various structural analysis and optical techniques as a function of deposition temperature. Polysilicon films of high quality can only be obtained by deposition in the amorphous phase and subsequent crystallization.
Single-valued strength of ‘‘perfect’’ silica fibers
Authors: Kurkjian C. R. , Paek U. C.
Published: February 2003

An analysis has been made of the tensile strength statistics of two silica fibers with quite different degrees of diameter uniformity. It has been found that the coefficient of variation in diameter (νd) is equal to that in minimum diameter (νd,min) and that the measured coefficient of variation in breaking load (νL) and breaking stress (calculated assuming constant d) are twice this value. Since νL =νσ =2νd =2νd,min it is clear the apparent variability in strength is the result of the variability in diameter and therefore the real strength is essentially single valued. Because of this lack of statistical variation in breaking strength, it is suggested that these fibers are flaw-free as drawn.
Characteristics of Schottky diodes at 10.6 μm
Authors: Inoue N. , Harakawa K. , Yasuoka Y.
Published: February 2003

Antenna-coupled point contact n-Ge/tungsten Schottky diodes have been used to detect CO2 laser radiation, and a very clear antenna pattern is obtained for an electric field polarized in the plane of incidence. The polarity of the detected voltage of the diode at low frequency and CO2 laser frequency regions indicates that the nonlinear I-V characteristic of the diode at low frequency persists up to the CO2 laser frequency.
Origin of the difference in the open circuit voltage between p-i-n type and n-i-p type hydrogenated amorphous silicon solar cells
Authors: Sakata I. , Hayashi Y.
Published: February 2003

The origin of the difference in the open circuit voltage Voc between a p-i-n and n-i-p type hydrogenated amorphous silicon solar cells is discussed theoretically, considering the interaction of photogenerated free electrons and holes, i.e., the effect of a self-field. It has been clarified that the self-field aids the carrier collection in an n-i-p cell whereas it impedes the carrier collection in a p-i-n cell. This difference in the effect of the self-field on the photovoltaic process causes the difference in Voc between these two type cells.
Complete dielectric isolation by highly selective and self-stopping formation of oxidized porous silicon
Authors: Holmstrom R. P. , Chi J. Y.
Published: February 2003

Complete dielectric isolation of silicon regions 45 μm wide for microcircuits on silicon substrates is demonstrated by selective formation of oxidized porous silicon in heavily doped n-type regions. Anodic etching of n-type silicon in a hydrofluoric acid electrolyte exhibits a concentration-dependent voltage threshold. This voltage dependence allows the porous silicon formation process to be selective to heavily doped regions and self-stopping on lightly doped regions. Rapid oxidation of this porous silicon yields an oxide with dielectric properties approaching those of standard thermally grown silicon oxides. This process is an improvement over previously reported processes utilizing porous silicon in that wider regions (up to 300 μm) are dielectrically isolated by an oxide whose thickness is controllable and uniform so that stress and wafer warpage are minimized.
Low noise niobium dc SQUID with a planar input coil
Authors: de Waal V. J. , van den Hamer P. , Klapwijk T. M.
Published: February 2003

A practical all-niobium dc superconducting quantum interference device (SQUID) with a niobium spiral input coil has been developed. The SQUID utilizes submicron Josephson junctions. The best intrinsic energy resolution obtained with a 1-nH SQUID is 4×10−32 J/Hz. A 20-turn 1.2-μH input coil is coupled to a 2.3-nH SQUID with an efficiency of 0.5. The energy resolution with respect to the coil is 1×10−30 J/Hz.
Electron beam writing on a 20-Å scale in metal β-aluminas
Authors: Mochel M. E. , Humphreys C. J. , Eades J. A. , Mochel J. M. , Petford A. M.
Published: February 2003

Holes 20 Å diameter and lines 20 Å wide can be cut in sodium β-alumina, sodium β″ alumina, lithium β-alumina, potassium β-alumina, lead β-alumina, and silver β-alumina using a small focused electron probe (approximately 104 A/cm2). Drilling can proceed along any crystal direction in the specimen and can penetrate material more than 1000 Å thick maintaining the small (20 Å) diameter. The holes and lines remain stable and the specimen can be removed from the electron microscope and replaced later for further drilling or examination at reduced beam intensities.
Long wavelength Pb1−xSnxTe homostructure diode lasers having a gallium-doped cladding layer
Authors: Zussman A. , Feit Z. , Eger D. , Shahar A.
Published: February 2003

The electron concentration in Ga-doped liquid phase epitaxy (LPE) layers of Pb1−xSnxTe was studied as a function of the Ga concentration in the growth solution for various x compositions. Maximum electron concentrations of 5×1019 cm−3 and 2×1018 cm−3 were measured for x=0 and x=0.3, respectively—the highest values ever published for these LPE grown compositions. n+-p-p+ Pb1−xSnxTe homostructure diode lasers with a Ga-doped cladding layer were fabricated. The lasers showed extended wavelength ranges (11.5≤λ≤18.5 μm for x=0.24 and 8.2 μm≤λ≤11.2 μm for x=0.12), and low threshold current densities (30 A/cm at T=10 K). The threshold current density at low temperatures was found to be determined by excess tunneling currents.
Wave propagation in a finely laminated periodic elastoacoustic medium
Authors: Schoenberg Michael
Published: February 2003

The exact solution for plane wave propagation through periodically alternating solid and fluid layers has been derived for all frequencies and all wave numbers. In the low-frequency limit an explicit dispersion relation is found relating the wave slowness parallel to the layering to that perpendicular to the layering. At any angle of propagation, except perpendicular, there are two waves: a fast wave and a slow wave. The tangential motion across a solid fluid interface for the fast wave is in phase, and for the slow wave, out of phase. An equivalent medium is found which has the same equation of motion with an anisotropic density tensor as a periodically layered fluid, but which has a constitutive relation relating pressure and dilation which is nonlocal in space and time. This equivalent medium exhibits the same wave propagation properties as the layered solid, fluid medium in the long wavelength limit and is called an elastoacoustic medium.
c-axis inclined ZnO piezoelectric shear wave films
Authors: Wang J. S. , Lakin K. M.
Published: February 2003

This letter reports on the growth and characterization of ZnO films having c axis oriented 40° to the substrate normal. These films are of significant interest for shear wave generation for bulk wave delay lines and resonators. The films were grown on Si wafers or membranes under low pressure and high growth rate conditions in a reactive dc planar magnetron sputtering system having an auxiliary anode structure. Shear wave resonators were fabricated and used for film evaluation. A ZnO/Si composite resonator exhibited a Q of approximately 4600 at 293-MHz fundamental resonance. The effective coupling coefficient of the film alone was found to be 17% (k2=0.029) using an edge-only supported ZnO plate resonator. The temperature coefficient of the ZnO resonator was found to be −36 ppm/°C and −20.5 ppm/°C for the composite structure.
Isotopically selective photoionization of mercury atoms
Authors: Dyer P. , Baldwin G. C. , Kittrell C. , Imre Dan G. , Abramson E.
Published: February 2003

Isotopically selective resonance ionization of mercury atoms has been accomplished by three-step excitation via the 6 3P1 and 8 1S0 excited states. Three collinear beams, respectively 254, 286, and 532 nm, from two dye lasers and a pulsed neodymium:yttrium aluminum garnet (ND:YAG) pump laser, were passed through a closed mercury vapor cell containing electrodes to which the ions were drawn by an electric field. The ion current and the 254-nm fluorescence radiation were measured as a function of laser wavelengths. Hyperfine structures for the 254- and 286-nm transitions were observed.
Reactive outdiffusion of contaminants from (AlGa)As laser facets
Authors: Tihanyi P. , Scifres D. R. , Bauer Robert S.
Published: February 2003

We report improved overcoating adhesion and reduction of facet contaminants by predeposition of a 20–50-Å layer of metallic Al onto cleaved GaAlAs 〈110〉 and GaAs 〈110〉 mirror facets. Electrical, adhesive, and Auger measurements show impurity outdiffusion from the facet into the Al interlayer. This procedure reduces the oxygen by at least a factor of 5 by gettering contaminants from the facet as effectively as ion beam milling, without producing (AlGa)As surface nonstoichiometry inherent in the sputtering process.
Threshold behavior of super-radiance under continuous pumping
Authors: Lee C. T.
Published: February 2003

Recognizing that the super-radiance emission rate is proportional to the product of the number of cooperative atoms in the upper level and that in the lower level, we propose simple deterministic and stochastic equations to describe the evolution of the super-radiant atomic system pumped continuously at a constant rate. The steady-state solutions of these equations display threshold behavior very similar to the laser. This provides yet another example of nonequilibrium phase transition of the second order.
Influence of transient absorber gratings on the pulse parameters of passively mode-locked cw dye ring lasers
Authors: Kühlke D. , Rudolph W. , Wilhelmi B.
Published: February 2003

A theoretical explanation of the experimental results obtained by the method of colliding pulse mode locking (CPM) is given. It is shown that, compared to other passive methods, the coherent interaction of the counter-running pulses in the thin absorber yields considerably shorter pulses with a more favorable stability region. Deviations from an amplifier position being symmetric with respect to the amplification of the counter-running pulses lead to different energies of the pulses and to a strong decrease of the stability range of the CPM.
Quantum transport in a single layered structure for impurity scattering
Authors: Lee Johnson , Spector Harold N. , Arora Vijay K.
Published: February 2003

In this letter we present results for the mobility of electrons confined in a layered structure when the scattering of the confined carriers is dominated by ionized impurity scattering. In the size quantum limit, the mobility is found to decrease with the layer thickness in contrast to the situation where acoustic phonon scattering is dominant. In the latter case, the mobility is found to increase with the layer thickness. We have considered the effects of both background and remote impurities on the mobility of the confined carriers. The results which we have obtained are considerably different from those currently available in the literature.
Effect of electric fields on Cr redistribution at GaAs surfaces
Authors: Yee Camellia M. L. , Fedders P. A. , Wolfe C. M.
Published: February 2003

During the annealing of ion-implanted Cr-doped GaAs, Cr often redistributes and accumulates at the surface. Although this behavior has been attributed to strain fields and other mechanisms, the widths of these accumulation regions suggest that electric fields due to surface states are a limiting factor in Cr redistribution. For this reason we have developed a thermodynamic model for Cr redistribution which takes into account the electric field due to surface states. A qualitative fit to SIMS data on annealed unimplanted GaAs samples can be obtained with this model. We have also used applied voltages during annealing to modify the amount of band bending and Cr buildup at the surface. This experiment indicates that the accumulated ions are positively charged. We conclude from these experiments that electric fields play a significant role in the redistribution of Cr at GaAs surfaces.
Time-dependent small-angle x-ray scattering from stress-induced crazes in polymers
Authors: Rothwell W. S , Martinson R. H. , Gorman R. L.
Published: February 2003

High-intensity x radiation from the Stanford Synchrotron Radiation Laboratory storage ring has been used in a small-angle scattering mode to study dynamic deformation behavior in polymers. Complete scattering curves were obtained as a function of time during relaxation with the strain direction oriented parallel and perpendicular to the plane of measurement. Interpretation is made of the resulting information on relative number, size, and time dependence of heterogeneities. A tentative model proposes that the application of stress starts a rapid creation of approximately uniform spherical voids which migrate and coalesce to form crazes and relieve the stress.
Electrical properties and ion implantation of epitaxial GaN, grown by low pressure metalorganic chemical vapor deposition
Authors: Khan M. A. , Skogman R. A. , Schulze R. G. , Gershenzon M.
Published: February 2003

High quality single crystal GaN films with extremely uniform thicknesses have been grown in low pressure metalorganic chemical vapor deposition system using the reaction of (C2H5)3Ga with NH3. Electrical and optical properties of the layers were measured. Schottky barriers were fabricated after compensating the background donor concentration (typically ND ∼1×1019 cm−3) with Be+ or N+ implants. These Schottky barriers were electrically and optically characterized.
High optical power cw operation in visible spectral range by window V-channeled substrate inner stripe lasers
Authors: Yamamoto S. , Hayashi H. , Hayakawa T. , Miyauchi N. , Yano S. , Hijikata T.
Published: February 2003

High optical power cw operation has been achieved at the wavelength range of 780 nm by newly developed window V-channeled substrate inner stripe lasers. This laser consists of a waveguiding window region with a plane active layer and a stimulated region with a crescent active layer. These two regions are coupled to each other. cw optical power over 70 mW and low cw threshold current of 30 mA were obtained. Moreover, the fundamental transverse mode was observed up to 60 mW, and it was found that the beam waist along the junction existed at the mirror.
Subnanosecond time-resolved photoconductive response of semiconducting diamond
Authors: Young Jeff F. , Vermeulen L. A. , Moss D. J. , van Driel H. M.
Published: February 2003

The time-resolved photoconductive response of several natural and synthetic semiconducting (IIb) diamonds has been measured at room temperature using an optoelectronic cross-correlation technique. The response times are between 100 and 300 ps, indicating a capture cross section for the photoexcited holes of ∼4×10−13 cm−2. We have found that IIb diamonds can serve as a simple, rugged pulsed laser detector for 0.45<λ<4.2 μm.
Correlation of Fermi-level energy and chemistry at InP(100) interfaces
Authors: Waldrop J. R. , Kowalczyk S. P. , Grant R. W.
Published: February 2003

X-ray photoemission spectroscopy data are used to correlate the interface Fermi-level pinning energy EiF and the corresponding interface chemistry for n-type and p-type InP (100) samples simultaneously subjected to a series of surface treatments. Interfaces of Schottky-barrier contacts formed during a sequence of Au and of Al depositions made both onto chemically etched and thermally cleaned InP surfaces were investigated. Changes in EiF of up to ∼0.6 eV in the upper half of the InP band gap occurred in response to changes in interface chemistry. The observed behavior of EiF is interpreted in terms of a single defect model with multiple charge states.
Flame annealing of arsenic and boron implanted silicon
Authors: Narayan J. , Young R. T.
Published: February 2003

We have investigated the characteristics of flame annealing of ion implantation damage in (100) and (111) silicon substrates using transmission electron microscopy and Van der Pauw measurements. The temperature of the hydrogen flame ranged from 1050 to 1200 °C and the interaction time from 5 to 10 s. Transmission electron microscopy studies showed that a ‘‘defect-free’’ annealing could be achieved with concomitant full electrical activation of dopants. The Hall mobility of flame annealed specimens was found to be comparable to pulsed laser annealed specimens.
Coherent behavior of 2N-Josephson junction closed loop
Authors: Kobayashi Tadayuki , Hamasaki Katsuyoshi , Kondoh Nobuyoshi , Komata Toranosuke , Yamashita Tsutomu
Published: February 2003

Voltage-current characteristics of a superconducting closed loop which consists of a parallel combination of two linear series arrays of N-Josephson junctions are theoretically and experimentally investigated for N=3. The results show that the rf-induced constant voltage steps in v-i characteristics in the presence of the rf radiation of frequency F appear at voltages corresponding to nNFΦ0 with an integer n. We find that the junctions show a coherent behavior even though the closed loop does not consist of identical junctions. The voltage standard application of this circuit seems feasible.
Continuous 300-K laser operation of strained superlattices
Authors: Ludowise M. J. , Dietze W. T. , Lewis C. R. , Camras M. D. , Holonyak N. , Fuller B. K. , Nixon M. A.
Published: February 2003

Continuous (cw) 300-K laser operation of a 66-period lower energy GaAs-InxGa1−xAs (x∼0.2) strained superlattice (SL) and a higher energy 128-period GaAs1−xPx-GaAs (x∼0.25) strained SL is demonstrated. The strained SL’s are grown by organometallic vapor phase epitaxy (OMVPE) or metalorganic chemical vapor deposition (MOCVD) with higher gap quaternary confining layers and LB ∼75 Å barriers and Lz ∼75 Å quantum wells. These SL’s are unstable during high level excitation, failing in 2–20 min when operated cw at 300 K as photopumped lasers.
Heteroepitaxial Si films on yttria-stabilized, cubic zirconia substrates
Authors: Golecki I. , Manasevit H. M. , Moudy L. A. , Yang J. J. , Mee J. E.
Published: February 2003

Epitaxial single-crystal growth of Si films has been achieved on the (100), (110), and (111) planes of yttria-stabilized, cubic zirconia single crystals. The Si films were grown by the pyrolysis of SiH4 at temperatures in the range 950–1075 °C and at deposition rates of 0.08–1.2 μm/min. The structural and electrical properties of the Si films have been determined by Rutherford backscattering and channeling, x-ray diffraction, and Hall effect measurements. Several 0.4–0.5-μm-thick (100) and (110) Si films on cubic zirconia were found to be of higher crystal quality than commercial (100) Si-on-sapphire films of similar thickness.
Transient photoconductivity studies of the light soaked state of hydrogenated amorphous silicon
Authors: Street R. A.
Published: February 2003

Studies of transient photoconductivity show that the primary effect of light soaking in hydrogenated amorphous silicon is to introduce dangling bonds of bulk density 1016–1017 cm−3. Light soaking reduces the μτ product of both electrons and holes to values which are quantitatively related to the observed increase in the dangling bond electron spin resonance (ESR) spin density. In addition, no change in the carrier drift mobilities is detected after light soaking.
Fabrication and Josephson behavior of high-T
c superconductor-normal-superconductor microbridges
Authors: de Lozanne A. , DiIorio M. S. , Beasley M. R.
Published: February 2003

We describe a simple new technique for fabricating superconductor-normal metal-superconductor (SNS) microbridges that allows the use of high-Tc materials. We have used this technique to make the first high-Tc SNS microbridges, incorporating Nb3Ge, Nb3Sn, and Nb as the superconductor, and Cu and Au as the normal metal. These devices have a Tc up to 19 K and exhibit very good electrical characteristics over a wide range of temperatures. Both the dc and the ac Josephson effects are clearly displayed by these junctions.
Intense polarized 3He source for use in fusion reactors
Authors: Murnick D. E.
Published: February 2003

A method is described to produce intense beams of nuclear polarized 3He atoms for injection into a fusion reactor. The polarized beam is produced by charge exchange of He+ in sodium vapor followed by selective optical pumping with circularly polarized laser radiation at 1.08 μ.
Conical transducer for generation of acoustic waves in fluids
Authors: Baer R. L. , Khuri-Yakub B. T. , Kino G. S.
Published: February 2003

A conical transducer has been developed as an extension of the edge-bonded transducer. Surface waves on the inside of a conical radiator are used to launch longitudinal waves in fluids. This transducer offers a broad bandwidth and low sidelobe levels.
Migration of implanted indium in silicon as a function of thermal annealing
Authors: Reihl R. F. , Smith G. A. , Katz W. , Koch E. F.
Published: February 2003

The study of indium implantation in silicon has gained considerable interest because of its potential in producing high value resistors in integrated circuits. We have studied the redistribution of indium as a function of high-temperature anneal and dose. While the data show some anomalous redistribution, the bulk of the implanted indium remains undisturbed supporting a trapping mechanism during solid phase epitaxial growth for high-temperature thermal anneals up to 1050 °C.
Reinvestigation of first phase nucleation in planar metal-Si reaction couples
Authors: Ronay Maria
Published: February 2003

It is proposed that the first nucleating phase in planar metal-silicon reaction couples is that congruently melting phase neighboring the central eutectic in the phase diagram, which is closer in composition to the diffusing species. This phase also must have a low interfacial free energy with one of the elements constituting the phase diagram. The low interfacial free energy is indicated either by eutectic formation with, or, by epitaxial growth on one of the elements. It is suggested that a low-energy interface is no barrier to diffusion; therefore, phases that nucleate first in metal-silicon reaction couples are not good as diffusion barriers.
Temperature and field dependence of the generation of interface states in the Si-SiO2 system after high-field stress
Authors: Wu J. K. , Lyon S. A. , Johnson W. C.
Published: February 2003

We have studied the time dependence of the generation of interface states in the Si-SiO2 system after metal-oxide-semiconductor capacitors were stressed by a 7.4-MV/cm gate positive electric field for 8 h at 90 K. The interface state density increased logarithmically with time for temperatures between 180 and 300 K with fields between +2 and −2 MV/cm. An analysis based upon a distribution of formation energies is proposed to explain the logarithmic time dependence. We find that there are two peaks in this distribution. One peak at 0.7 eV is field independent while the other at 0.9 eV disappears when a zero or negative bias is applied.
On the mechanism of light-induced effects in hydrogenated amorphous silicon alloys
Authors: Guha S. , Yang J. , Czubatyj W. , Hudgens S. J. , Hack M.
Published: February 2003

We have investigated the effects of both forward bias current soaking in the dark and prolonged light exposure on the photovoltaic properties of lightly doped, n- and p-type hydrogenated amorphous silicon Schottky barrier diodes. The results show that recombination rather than single carrier trapping is responsible for the light-induced changes.
Development of silver sensitized germanium selenide photoresist by reactive sputter etching in SF6
Authors: Huggett P. G. , Frick K. , Lehmann H. W.
Published: February 2003

Silver sensitized germanium selenide/polymer bilevel resist system has been used to pattern structures in SiO2 on silicon. Using reactive sputter etching in an SF6 plasma for developing germanium selenide gives superior results compared to CF4 or CHF3 in terms of sensitivity; 500:1, contrast; 7, and sensitivity; 50 mJ/cm2 at 436 nm. By this method 1-μ lines and spaces and 1-μ contact holes have been defined in germanium selenide. These have been transferred into polymer and SiO2 using standard reactive sputter etching with O2 and CHF3, respectively.
cw electro-optical characteristics of graded-index waveguide separate-confinement heterostructure lasers with proton-delineated stripe
Authors: Tsang W. T. , Hartman R. L.
Published: February 2003

Shallow proton-bombarded stripe-geometry (5 μm wide, 380 μm long) lasers were fabricated from graded-index waveguide separate-confinement heterostructure (GRIN-SCH) laser wafers grown by molecular beam epitaxy (MBE). Low median cw threshold currents of ∼50 mA were obtained for this stripe-geometry gain-guided structure. Such threshold currents represent a reduction by 25% from those of similar geometry lasers fabricated under the same technologies from the lowest threshold regular double heterostructure (DH) lasers wafers grown by MBE or liquid phase epitaxy (LPE). Up to the maximum measured output power of 10 mW/mirror (cw) the linearity is good and the symmetry of the output powers from both mirrors of these GRIN-SCH (gain guided) lasers compares well to those lasers of the buried heterostructure type (index guided). The average intrawafer variation in the symmetry of the two end mirror outputs can be characterized by the average of the quantity 〈α〉, which is the deviations from unity of the A/B power output ratio measured at 3 mW. For three LPE grown DH wafers 〈α〉 is about ±20%, and varies from ±5% to ±8% for three MBE grown DH wafers. For three GRIN-SCH wafers, 〈α〉 between ±3% and ±0.8% was obtained. The standard deviations of the cw threshold current distributions for MBE grown lasers (σ≂4 mA dc) are one-half that for LPE grown lasers. This documents the improved layer thickness and composition control achievable with the MBE growth procedure.
Diffraction coupled phase-locked semiconductor laser array
Authors: Katz J. , Margalit S. , Yariv A.
Published: February 2003

A new monolithic, diffraction coupled phase-locked semiconductor laser array has been fabricated. Stable narrow far-field patterns (∼3°) and peak power levels of 1 W have been obtained for 100-μm-wide devices with threshold currents as low as 250 mA. Such devices may be useful in applications where high power levels and stable radiation patterns are needed.
1-Gbit/s code generator and matched filter using an optical fiber tapped delay line
Authors: Jackson K. P. , Newton S. A. , Shaw H. J.
Published: February 2003

The macrobend optical fiber tapped delay line is a new device which is ideally suited for the processing of signals that have very large bandwidths. Two new applications of this device are presented: code generation and matched filtering. An 8-bit code at 1 Gbit/s was generated with a programmable eight tap delay line having 1-ns tap intervals. Matched filtering at a rate of 1 Gbit/s was also demonstrated with a similar deivce. This letter presents the first fiber optic code generator/matched filter of its kind.
Semiconductor integrated étalon interference laser with a curved resonator
Authors: Antreasyan Arsam , Wang Shyh
Published: February 2003

A semiconductor interferometric laser with a resonator having curved and straight segments is reported. Interference is caused by internal reflection at the junction discontinuity between curved and straight segments due to a slight difference between the wave propagation constants. Lateral mode stability is provided by the fabrication of a buried heterostructure type laser cavity. The outstanding features of the laser are (1) very stable single longitudinal mode and stable lateral mode operation, and (2) a wavelength locking range of up to 23 °C within which the wavelength changes at a rate of 0.5–0.6 Å/°C.
Low loss poly(methylmethacrylate-d8) core optical fibers
Authors: Kaino Toshikuni , Jinguji Kaname , Nara Shigeo
Published: February 2003

Low loss plastic optical fibers (POF’s) have been prepared employing a poly(methylmethacrylate-d8) core and fluorinated alkyl methacrylate copolymer cladding with attenuation losses of 20, 25, and 50 dB/km at wavelengths of 660, 780, and 850 nm, respectively. These values were attained using the POF fabrication method which incorporates a closed polymerization and fiber drawing procedure. The POF can allow optical signal transmission over about 1300 m at −34 dBm at a rate up to 10 MHz using a display grade GaAlAs light-emitting diode whose emission power at 660 nm and 20 mA of forward input current is 1 mW. The loss limit of this poly(methylmethacrylate-d8) core POF is estimated to be 10 dB/km at 680 nm.
Suppressing Al outdiffusion in implantation amorphized and recrystallized silicon on sapphire films
Authors: Reedy R. E. , Sigmon T. W. , Christel L. A.
Published: February 2003

In this work we have used a dual implant and anneal process to significantly improve the crystalline quality of 0.3-μm silicon on sapphire films while simultaneously minimizing the outdiffusion of free Al from the sapphire into the Si layer. The crystalline quality, as measured by MeV 4He+ ion channeling closely approached 〈100〉 bulk Si values and the Al concentration, as measured by secondary ion mass spectrometry, was less than 3×1015 cm−3. An explanation for why similar techniques result in large amounts of aluminum outdiffusion when applied to 0.5-μ films is proposed.
Photoconductivity enhancement by light trapping in rough amorphous silicon
Authors: Tiedje T. , Abeles B. , Cebulka J. M. , Pelz J.
Published: February 2003

The photoconductivity of amorphous silicon films is shown to be enhanced by a factor of 25 at long wavelengths when the material is deposited on a rough, reflecting substrate. In a solar cell, this light trapping effect would produce a 4.5-mA/cm2 increase in the short circuit current.
cw laser activated flow applied to the planarization of metal-oxide-semiconductor field-effect transistor structures
Authors: Delfino M. , Reifsteck T. A.
Published: February 2003

The cw laser activated flow method is applied to the planarization of phosphosilicate glass passivated n-channel metal-oxide-semiconductor field-effect transistors with various device geometries. Flow is demonstrated over a range of raster scan velocities and at all principal CO2 laser wavelengths. Device characteristics, namely, threshold voltage, junction breakdown voltage, and transconductance, are essentially unaffected by the laser irradiation, whereas the polycrystalline silicon interconnect resistance is reduced by about 20%. The effect of thermal conductivity of the phosphosilicate glass on the laser flow threshold is shown.
Tunneling current microscopy
Authors: Lin P. S. D. , Leamy H. J.
Published: February 2003

The field dependence of electron beam induced current in thin oxide (22.5 nm) capacitors has been studied with a view of using the induced current for detecting defects in such devices. Results indicate that the induced current follows Fowler–Nordheim tunneling behavior when the field exceeding 4 MV/cm, and that a certain type of defect in thin oxide capacitors can be imaged with high contrast and low noise. A high current gain (∼103) of the induced current was also obtained. These findings open the possibility of acquiring information on the quality and reliability of composite metal-insulator-metal/semiconductor structures, and of achieving a high current for signal amplification.
Electron transport in InP at high electric fields
Authors: Windhorn T. H. , Cook L. W. , Haase M. A. , Stillman G. E.
Published: February 2003

The high field (>30 kV/cm) electron drift velocity in n-type (100) InP has been measured at temperatures from 95 to 400 K and electric field strengths up to 215 kV/cm using a fixed frequency (7.54 GHz) microwave time-of-flight technique. The velocity decreases monotonically with increasing electric field strength at all temperatures over the entire range of field strengths investigated. At 300 K the electron drift velocity in InP is 1.2 times the velocity in GaAs at 150 kV/cm, and increases to 1.34 times the velocity in GaAs when the field is lowered to 30 kV/cm.
Superconducting current injection transistor
Authors: Van Zeghbroeck Bart J.
Published: February 2003

A new superconducting transistor has been investigated, both theoretically and experimentally. The device has a current gain of 10 and an estimated power-delay product of 90 aJ. It is shown that in principle, the gain of the device is limited only by its length. Possible applications include analog amplification and digital logic.
Subharmonic generation in Josephson junction fluxon oscillators biased on Fiske steps
Authors: Soerensen M. P. , Christiansen P. L. , Parmentier R. D. , Skovgaard O.
Published: February 2003

Numerical integration of the perturbed sine-Gordon equation describing a long overlap-geometry Josephson junction in a magnetic field indicates a branched structure of the first Fiske step. The major portion of the step corresponds to a simply periodic fluxon oscillation whereas the branches are characterized by subharmonic generation.
Size effect on magnetic moment density of dispersed nickel
Authors: Cale T. S. , Richardson J. T. , Ginestra J.
Published: February 2003

An extension of superparamagnetic superposition analysis is used to show a crystallite size effect on the magnetic moment density of nickel dispersed on silica. A clear effect on room-temperature moment density is seen for samples with crystallites much less than 3 nm in radius.
New approach to electron beam lithography
Authors: Fulton T. A. , Dolan G. J.
Published: February 2003

We describe a new approach to the lithography of thin films and thin-film devices. Instead of fully exposing a pattern in, for example, electron beam or ion beam lithography, only the outlines of individual features in the pattern are exposed, leaving the completion of the features to a later processing step which is novel in concept but compatible with conventional processing. This approach can potentially reduce exposure time considerably, reduce proximity effects in the exposure process and reduce electron damage to the substrate. As a specific example we describe a process applicable to electron beam fabrication of chrome master masks for photolithography.
Hard carbon coatings with low optical absorption
Authors: Dischler B. , Bubenzer A. , Koidl P.
Published: February 2003

Hydrogenated amorphous (a-C:H) films were prepared by rf-plasma deposition from benzene vapor. Complete optical absorption spectra from the UV to the IR (0.2–20.0 μm) have been measured. The optical gap depends linearly on hydrogen content and Eopt can be varied between 0.8 and 1.8 eV. For energies below Eopt the films are almost transparent and absorption is especially low in the 2–6-μm region (e.g., α=15 cm−1 at λ=2.8 μm). Sharp C–H stretch absorption bands occur near 3.4 μm, giving insight into the microstructure of the films. A newly reported weak band at 3.03 μm is first evidence for C–C triple bonds (sp1 hybridization) in a-C:H, where sp3 (single) and sp2 (double) C–C bonds dominate.
Runaway self-absorption in multikilowatt CO2 lasers
Authors: Kaye A. S. , Naylor D. L.
Published: February 2003

Runaway self-absorption within a CO2 laser cavity, recently reported at high pressure, has also been observed in a low pressure (50 mbar), multikilowatt cw CO2 laser. A numerical model of the laser discharge is used to simulate the runaway absorption and gives results consistent with experiment. Runaway absorption is readily suppressed by eliminating regions of stagnant gas within the cavity.
Phase-locked (GaAl)As laser emitting 1.5 W cw per mirror
Authors: Scifres D. R. , Burnham R. D. , Lindström C. , Streifer W. , Paoli T. L.
Published: February 2003

A phase-locked multiple quantum well (GaAl)As injection laser is demonstrated to emit over 1.5 W/mirror (>3 W total) cw output power at ∼8350 Å with a maximum power conversion efficiency of 17.4%.
Twin-channel substrate-mesa-guide injection lasers fabricated by organometallic vapor phase epitaxy
Authors: Ackley D. E. , Hom G.
Published: February 2003

An easily fabricated high-power index-guided laser, the twin-channel substrate-mesa-guide (TCSM) laser, has been developed for applications in recording, printing, and communications. The TCSM laser is fabricated by one-step organometallic vapor phase epitaxy (OMVPE) on photolithographically patterned and etched substrates. Linear output characteristics were observed to 40 mW cw with corresponding operation in zero order lateral and transverse modes and no astigmatism. Stable single longitudinal mode oscillation also resulted from the strong refractive index guiding produced by the nonplanar structure.
A new type of laser probe
Authors: Stearns R. G. , Kino G. S. , Khuri-Yakub B. T.
Published: February 2003

A new technique to measure surface acoustic wave beam profiles is described. A measurement is made of the average phase change of the acoustic wave resulting from periodic heating of the sample surface by an incident modulated laser beam. Scanning of the laser beam across the acoustic wave results in a profile of the energy density in the acoustic beam. To measure the phase change, a surface acoustic wave oscillator configuration is used. Possible application of the technique to the measurement of applied and residual surface stress is discussed.
Laser induced deposition of zinc oxide
Authors: Solanki R. , Collins G. J.
Published: February 2003

We have used an excimer laser to photodeposit uniform (±5%) films of zinc oxide from dimethylzinc and nitrogen dioxide. Deposition rates of 3000 Å/min over 2 cm×5 cm areas were obtained. We have measured the stress, refractive index, etch rate, adhesion, pinhole density, and the stoichiometry of these photodeposited films.
Carbon fibers produced by pyrolysis of natural gas in stainless steel tubes
Authors: Tibbetts Gary G.
Published: February 2003

Carbon fibers of uniform diameter have been grown by pyrolysis of natural gas in type 304 stainless steel (18% Cr, 8% Ni) tubes at temperatures between 950 and 1075 °C. The method utilizes the circulation of wet hydrogen outside the growth tube in order to promote effective nucleation. Fibers 12 cm long having average moduli of 1.8×1011 Pa have been grown.
Rapid temperature variation of hopping conduction in GaAs low-temperature bolometers
Authors: Wigmore J. K. , Tlhabologang B.
Published: February 2003

The very rapid temperature dependence between 1 and 4 K of the resistivity of GaAs bolometers was found to follow ρ∼exp(AT−1/4). The most plausible attribution of this behavior was to variable range, single particle, hopping, and our data were consistent with the model of Apsley and Hughes.
Glow discharge polycrystalline silicon thin-film transistors
Authors: Hirai Y. , Osada Y. , Komatsu T. , Omata S. , Aihara K. , Nakagiri T.
Published: February 2003

Thin-film transistors were fabricated from polycrystalline silicon films which were produced by glow discharge decomposition of silane at 500 °C on thermal oxidized silicon substrates. The dependence of the crystalline and electrical properties was observed for thicknesses from about 500 to 4500 Å. As the film grew thicker, the strongly (110) oriented polycrystalline structures became predominant. The conductivity changed from 4×10−9 to 10−6 (Ω cm)−1 and the activation energy from 0.57 to 0.5 eV. The field-effect mobility of these thin-film transistors also varied with the thickness of the film.
Lateral dopant transport during laser recrystallization of polysilicon
Authors: Kamins T. I.
Published: February 2003

Significant lateral dopant transport occurs during seeded laser recrystallization of polysilicon. Both spreading-resistance measurements and voltage-contrast scanning electron microscopy show that phosphorus, arsenic, and boron are transported several tens of microns in the direction of the beam travel during recrystallization, while much less transport is observed in the other directions. The dopant motion orthogonal to the beam scan is consistent with liquid-phase diffusion.
A high-power, narrow linewidth XeCl* oscillator
Authors: Bourne O. L. , Alcock A. J.
Published: February 2003

A narrow linewidth (Δλ=0.0004 Å) modular dye laser system has been constructed and used to investigate the gain characteristics of a XeCl* oscillator. When operated as a free-running oscillator lasing occurred simultaneously on the Bv=0→Xv=1 and Bv=0→Xv=2 transitions. The injection of 20 μJ of UV radiation from the dye chain was sufficient to confine the entire output to either one of these two transitions. A measured linewidth of 0.0004 Å was obtained at average power levels of up to 5 W.
Heavy ion beam pumped He-Ar laser
Authors: Ulrich A. , Bohn H. , Kienle P. , Perlow G. J.
Published: February 2003

A 100-MeV 32S beam was used to pump a He-Ar gas laser. Laser action of the 1.79-μm line was observed above a threshold of 33-W beam power input. The light conversion efficiency is about 1×10−4 with a (99%)He-(1%)Ar gas mixture at 200-mbar pressure and 132-W input power.
Ultrasonic switching of a bistable liquid crystal cell
Authors: Hamidzada W. , Letcher S. V.
Published: February 2003

The response of a twisted nematic cell to a tone burst of ultrasound has been investigated. The cell is more sensitive than an ordinary nematic cell and, because it has two stable configurations, can store the acoustic signal. Over a wide range of acoustic pulse widths, the threshold for switching from one stable state to the other depends on the total acoustic energy of the pulse.
Phonon echoes in piezoceramic lead-zirconate-titanate
Authors: Holt R. M. , Fossum J. O.
Published: February 2003

Two-pulse phonon echoes have been generated in piezoceramic lead-zirconate-titanate, using an electric field at twice the frequency of the ultrasonic waves. The echo properties with respect to pulse width, electric field, frequency, and temperature dependences have been studied. It is demonstrated how the phonon echo can be utilized in sorting the pure sound absorption from the grain scattering losses in a ceramic material.
Theoretical evaluation of the rare-gas diluent effects for an electron-beam-excited XeCl laser
Authors: Kannari Fumihiko , Suda Akira , Obara Minoru , Fujioka Tomoo
Published: February 2003

The effect of various rare-gas diluents on the operating performance of the e-beam-excited XeCl laser is theoretically analyzed. The analysis of the XeCl* pumping process and the extraction process could solve the dependence of the intrinsic efficiency, small-signal gain, and absorption on the rare-gas diluent. As a result, there is no appreciable difference in the intrinsic efficiency between the Ar-based and the Ne-based mixtures. Selecting the optimum excitation parameters, the highest intrinsic efficiency of 5% is achieved for both diluents. Although the highest small-signal gain is achieved without a diluent gas, the extraction efficiency is reduced and the intrinsic efficiency is small due to the large amount of three-body collisional quenching.
Technique to predict specimen failure in cyclic fatigue tests
Authors: Tamada N. , Iwasa Y.
Published: February 2003

We report a technique with which to predict specimen failure from cyclic fatigue tests. The technique observes one of the resonant frequencies of the specimen; A definite shift in the resonant frequency has seen to occur preceding failure; this shift may be used to predict specimen failure.
Effect of pressure differential on channeling in thin Si crystals
Authors: Alexander R. B. , Johnson S. C. , Padmanabhan K. R. , Buchholz J. C.
Published: February 2003

The effect on ion channeling in thin Si single crystals of distortion produced by a pressure differential has been investigated. At a threshold pressure of several Torr in a Si-air cell, an abrupt increase occurs in the channeling minimum yield. Measurements have been made of the distortion using reflection of laser light, which produces an unusual interference pattern. A geometric model is proposed in which the minimum yield is determined by the tilting of the channels perpendicular to the bowed crystal surface.
Defect nature of the 0.4-eV center in O-doped GaAs
Authors: Look D. C. , Chaudhuri S. , Sizelove J. R.
Published: February 2003

We have studied the Ec −0.4 eV center in O-doped GaAs by a combination of temperature-dependent Hall-effect measurements, spark-source mass spectroscopy, and secondary-ion mass spectroscopy. The conclusion is that neither O nor any other impurity can account for the 0.4-eV center; therefore, it is a pure defect.
X-ray evidence for a terraced GaAs/AlAs superlattice
Authors: Neumann D. A. , Zabel H. , Morkoç H.
Published: February 2003

We report an x-ray diffraction study of a GaAs/AlAs superlattice, showing satellite reflections which lie on a line making a constant, nonzero angle with the [00L] reciprocal lattice rod containing the fundamental reflections. The results indicate a terraced superlattice structure in which the chemical modulation of the GaAs/AlAs layers is tilted with respect to the (001) lattice planes. This tilt imposes a reduced lateral domain size on the superlattice, which can be deduced from the angular widths of the satellite reflections.
Shubnikov–de Haas effect in (111)-epitaxial, n-type PbTe films with substrate-induced strain
Authors: Martinez Antonio , Houston Bland
Published: February 2003

Shubnikov–de Haas (SdH) magnetoresistance oscillations were observed in n-type (111)-oriented PbTe films during the same thermal cycle in which low-temperature weak-field magnetoresistance (WFMR) measurements, already reported [R. S. Allgaier, R. J. Abbundi, Bland Houston, J. L. Davis, A. Martinez, and J. B. Restorff, Appl. Phys. Lett. 41, 941 (1982)], were made. Analysis of the SdH data supports the conclusion from the 4.2-K WFMR data that nearly all of the carriers are transferred into the valley with its major axis normal to the film plane by substrate-induced strain. A more quantitative indication of the strain was obtained from the strong-field data by calculating the splitting of the L-point conduction-band minima caused by substrate-induced strain.
p
n junctions in tungsten diselenide
Authors: Späh R. , Elrod U. , Lux-Steiner M. , Bucher E. , Wagner S.
Published: February 2003

p n junctions in WSe2 have been fabricated for the first time. 10–20-μm-thick p-type layers were grown epitaxially on n-type substrates by vapor transport at 1060–1070 °C in sealed ampoules. 5–10-mm2 diodes exhibit rectification ratios ∼104 for 0.5-V bias. The diode space charge is ∼10 μm wide, indicating a small gradient in the density of electrically active impurities. At room temperature the diode current is dominated by generation/recombination. The current is space-charge limited at lower temperatures.