bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion implantation of Si in Be-implanted In0.53Ga0.47As
Authors: Choudhury A. N. M. M. , Slater N. J. , Tabatabaie-Alavi K. , Fonstad C. G.
Published: February 2003

Ion implantation of Si has been used to create n+ layers in Be-implanted InGaAs epilayers. A peak electron concentration of 7×1018 cm−3, a sheet resistance of 28 Ω per square, and an average electron mobility of 3000 cm2/Vs are measured in layers implanted with doses of 5.6×1013 cm−2 and 14×1013 cm−2 at 100 and 250 keV, respectively, and proximity cap annealed at 670°C for 15 min. Activation efficiencies of 86 and 38% are found for the low and high energy implants, respectively.
Observation of cyclotron resonance in the photoconductivity of two-dimensional electrons
Authors: Maan J. C. , Englert Th. , Tsui D. C. , Gossard A. C.
Published: February 2003

We have observed cyclotron resonance in the photoresponse of the two-dimensional electron gas at the interface of a GaAs/AlGaAs heterojunction. A 0.5% change in resistivity was obtained under resonance conditions for a far-infrared intensity of about 10−4 W/cm2.
Oxygen gettering by graphite baffles during organometallic vapor phase epitaxial AlGaAs growth
Authors: Kisker D. W. , Miller J. N. , Stringfellow G. B.
Published: February 2003

The effects of baffles upon the incorporation of oxygen into organometallic vapor phase epitaxial AlxGa1−x As have been investigated. Both graphite and SiC baffles have been studied. A simple model can be used to describe this effect as being dependent on the adsorption of trimethylaluminum onto the graphite, followed by reaction with oxygen to remove, or getter it from the gas stream.
Efficient GaAs solar cells formed by UV laser chemical doping
Authors: Deutsch T. F. , Fan John C. C. , Ehrlich D. J. , Turner G. W. , Chapman R. L. , Gale R. P.
Published: February 2003

ArF and XeF excimer laser radiation has been used to form p-n junctions in GaAs. The laser releases S atoms by the dissociation of H2S gas and simultaneously heats the substrate to allow incorporation of the S dopant. Solar cells having AM1 efficiencies of 10.8% have been fabricated from these junctions. The process can also produce doped GaAs layers with sheet resistances as low as 30 Ω/⧠.
Carbon in polycrystalline silicon, influence on resistivity and grain size
Authors: Bloem J. , Claassen W. A. P.
Published: February 2003

Polycrystalline silicon grown by chemical vapor deposition was doped with small carbon concentrations by the introduction of C2H2 into the gasflow. Incorporation of small carbon concentrations leads to a reduction in the resistivity of phosphorous-doped layers. Higher carbon concentrations lead to an increase in resistivity and a reduction in grain size accompanied by the formation of a second phase. These layers show an increased resistance to grain growth on annealing. The present study suggests a compensation of the electrical effects of surface states by the presence of carbon.
Growth of InP and InGaAsP (E
g≥1.15 eV) layers by liquid phase epitaxy under phosphorus overpressure
Authors: Keramidas V. G. , Temkin H. , Bonner W. A.
Published: February 2003

A method is presented for the liquid phase epitaxial growth of stoichiometric InP and InGaAsP (Eg⩾1.15 eV) epitaxial layers by creating a phosphorus overpressure in the growth ambient. The effectiveness of the method and the stoichiometry of InP layers can be monitored with the photoluminescent spectra of a phosphorus vacancy-impurity complex.
Thermal noise induced switching of Josephson logic devices
Authors: Klein M. , Mukherjee A.
Published: February 2003

Thermal noise induced switching of Josephson logic devices is studied, both theoretically and experimentally. The results are critical for the design of the operating bias points for these devices. An analysis of the relevant energy contours shows that a three-junction superconducting quantum interference device has the same noise switching rate as a point junction with the same maximum critical current. Experimental results, for the dependence of the thermal noise induced switching rate on the gate current bias ratio, are in very good agreement with the theory.
Textured germanium optical storage medium
Authors: Craighead H. G. , Howard R. E. , Liao P. F. , Tennant D. M. , Sweeney J. E.
Published: February 2003

A new optical storage medium is described which consists of a Ge film microscopically textured by reactive ion etching. The Ge surface, with a random array of decoupled columns of cross-sectional dimensions less than 100 nm, has a visible specular reflectance of less than 0.06. Reflective spots ∼1 μm in diameter have been produced on this surface by local heating with a low power laser beam. The fabrication, microstructure, and possibility of encapsulating the medium are discussed.
Optical-thermal induced total internal reflection-to-transmission switching at a glass-liquid crystal interface
Authors: Khoo I. C.
Published: February 2003

An intensity dependent change from a state of total internal reflection to transmission of an optical beam at a nonlinear glass-nematic liquid crystal interface is observed. The effect is attributed to optically induced molecular reorientation and thermal indexing, depending on the liquid crystal used.
AlN capped annealing of Si implanted semi-insulating GaAs
Authors: Okamura S. , Nishi H. , Inada T. , Hashimoto H.
Published: February 2003

AlN capped annealing can be used successfully for thin n-layer formation to minimize the thermal conversion effects. Si ions were implanted into Cr-doped semi-insulating GaAs substrates with 145 keV, to a dose of 2.40×1012 cm−2. Subsequently, the samples were annealed at 850 °C, 20 min with reactive sputtered AlN cap. The carrier profiles fit very well to the theoretical one. No thermal pits, cracks, and peeling-off were observed even on 1.2-μm-thick AlN cap after up to 1000 °C annealing.
Hot carrier effects in the collection efficiency of solar cells: a-Si:H
Authors: Rothwarf Allen
Published: February 2003

Recent models for the falloff in spectral response at short wavelengths in low mobility solar cell materials have been based upon the diffusion of thermalized carriers against the electric field to high recombination contacts or interfaces. These models neglect the excess energy imparted to the carriers by short wavelength light, that enable them to easily move against the field while thermalizing. Calculations of the distance the carriers diffuse before losing their excess energy by phonon emission indicate that in the high absorption coefficient region of a-Si:H up to 50% of the carriers can reach a contact or interface before thermalizing.
Reduction of fast surface states on p-type GaAs
Authors: Ahrenkiel R. K. , Wagner R. S. , Pattillo S. , Dunlavy D. , Jervis T. , Kazmerski L. L. , Ireland P. J.
Published: February 2003

Native oxides and oxyfluorides were grown on GaAs by a glow discharge plasma process. Analysis of metal-insulator-semiconductor structures based on oxyfluoride dielectrics indicated vastly different interface properties compared to pure oxide dielectrics. Whereas oxide structures showed high densities of fast surface states, oxyfluorides showed no evidence of such effects.
A novel normally-off camel diode gate GaAs field-effect transistor
Authors: Drummond T. J. , Wang T. , Kopp W. , Morkoç H. , Thorne R. E. , Su S. L.
Published: February 2003

A novel normally-off GaAs field-effect transistor utilizing a ’’camel diode’’ in place of a Schottky barrier and exhibiting excellent properties was demonstrated. The devicies have channel lengths of 3 or 4 μm, gate lengths of approximately 3 or 4 μm, and gate widths of 290 μm. The layers from which the devices were fabricated were prepared by molecular beam epitaxy and consisted of a 1-μm-thick Al0.3Ga0.7As buffer, an ∼500-Å GaAs layer doped to a level of 1.5×1017 cm−3 to form the channel, and 100-Å p+ Al0.47Ga0.53As and 400-Å n+ GaAs layers to form the gate. The devices exhibited transconductances as high as 80 mS/mm and excellent saturation characteristics.
Impedance conversion using quantum limit nonreciprocity for superconductor-insulator-superconductor mixer compensation
Authors: Whiteley S. R.
Published: February 2003

It is shown how a superconductor-insulator-superconductor (SIS) mixer when inductively terminated at the if port has inductive reactance at the signal port. This reactance may be used to compensate for the geometric capacitance of a conventionally operated SIS mixer over twice the bandwidth available through signal port resonance techniques.
Fluxon motion in long overlap and in-line Josephson junctions
Authors: Levring O. A. , Pedersen N. F. , Samuelsen M. R.
Published: February 2003

The motion of a single fluxon in long Josephson junctions of the overlap and inline geometries is investigated. It is concluded that if the junction is long and the damping is not too large then zero-field steps exist also in the inline junction. Thee zero-field steps are found to be mathematically identical to those of the overlap junctions in spite of the fact that the fluxon dynamics are quite different in the two cases.
A theory of longitudinal modes in semiconductor lasers
Authors: Lau Kam Y. , Yariv Amnon
Published: February 2003

A theory of longitudinal mode lasing spectrum of semiconductor lasers is developed which takes into account the nonuniform carrier and photon distributions and local gain spectrum shifts inside lasers with low end mirror reflectivities. The theory gives results consistent with observed longitudinal mode behavior in lasers with reduced facet reflectivity.
Detection of CF2 radicals in a plasma etching reactor by laser-induced fluorescence spectroscopy
Authors: Hargis P. J. , Kushner M. J.
Published: February 2003

Laser-induced fluorescence spectroscopy was used to detect ground-state CF2 radicals in 13.56-MHz discharge plasmas sustained in C2F6 and CF4 in a plasma etching reactor. Measurements of the relative CF2(X̃) density in each plasma as a function of discharge power demonstrated that CF2 densities were significantly higher in the C2F6 plasma. These results provide the first direct observation of CF2(X̃) radicals in a plasma etching reactor.
Strain of laser annealed silicon surfaces
Authors: Nemanich R. J. , Haneman D.
Published: February 2003

High resolution Raman scattering measurements have been carried out on pulse and continuous-wave laser annealed silicon samples with various surface preparations. These included polished and ion-bombarded wafers, and saw-cut crystals. The pulse annealing treatments were carried out in ultrahigh vacuum and in air. The residual strain was inferred from the frequency shift of the first-order Raman active mode of Si, and was detectable in the range 10−2–10−3 in all except the polished samples.
Interface-state generation during avalanche injection of electrons from Si into SiO2
Authors: Sunaga Toshio , Lyon S. A. , Johnson Walter C.
Published: February 2003

We have studied at both liquid-nitrogen temperature and room temperature the development of the interface states that are generated in the Si-SiO2 system when electrons are avalanche injected from the Si into the SiO2. Differences in development at the two temperatures indicate that the states are of two types. One appears immediately at liquid-nitrogen temperature and is probably identical with the states previously found to occur as the result of photoinjecting electrons through the interface. The other requires thermal energy to develop. These states may be associated with positive charge trapped at the interface and are probably related to those observed after radiation damage.
Threshold switching in hydrogenated amorphous silicon
Authors: den Boer W.
Published: February 2003

Threshold switching is observed in n+-i-n+ sandwich structures of hydrogenated amorphous silicon after an initial forming process. At the threshold voltage the device switches from a low conductance to a high conductance state. The devices remain stable after more than 109 switching operations at a pulse frequency of 10 kHz. It is suggested that in the high conductance state filamentary conduction occurs in a permanent altered region created during the forming process.
Onset of diffusion-drift emission regime and the transition from exponential to linear current-voltage characteristic of triangular barrier semiconductor structures
Authors: Buot F. A. , Krumhansl J. A. , Socha J. B.
Published: February 2003

Using a very simple physical model of charge motion in triangular barrier structure as a Brownian motion over a potential barrier, we show that there are essentially four regimes of operation, with increasing bias voltage, in these device structures. These are (a) the thermionic emission regime, (b) the diffusion emission regime, (c) the diffusion-drift emission regime, and (d) the linear current-voltage (I-V) characteristic, drift emission regime. The diffusion emission regime occurs only for a particular value of the applied voltage and marks the onset of diffusion-drift emission regime. This simple physical model gives excellent agreement with the experimental data, particularly under forward bias.
A picosecond transient digitizer based on nonlinear integrated optics
Authors: Normandin R. , Stegeman G. I.
Published: February 2003

An optical transient digitizer with subpicosecond resolution based on the convolution of optical signals in a nonlinear integrated optics waveguide and on charge coupled devices detector arrays is demonstrated for optical signals.
Compression of femtosecond optical pulses
Authors: Shank C. V. , Fork R. L. , Yen R. , Stolen R. H. , Tomlinson W. J.
Published: February 2003

We describe the generation and measurement of optical pulses as short as 30 fs. The pulses are produced using self-phase modulation in a short 15-cm optical fiber followed by a grating compressor.
Energy absorption during pulsed-laser annealing
Authors: Peercy P. S. , Wampler W. R.
Published: February 2003

Measurements of the energy absorbed in pulsed-laser annealing of Si and Al are consistent with annealing by thermal processes and directly yield the absorption coefficients in both the solid and liquid phases. For semiconductors, the technique described further permits measurement of the time during the laser pulse at which melting occurs which, when used in conjunction with the energy absorbed in the solid and liquid phases, allows critical evaluation of theoretical models for the annealing process.
Narrow 87Rb hyperfine-structure resonances in an evacuated wall-coated cell
Authors: Robinson H. G. , Johnson C. E.
Published: February 2003

Examination of 87Rb δF = 1, δ‖mF‖ = 1 hyperfine resonances in a 200-cm3 evacuated tetracontane wall-coated Pyrex cell which has been sealed since 1968 shows remarkable Dicke-narrowed sub-Doppler Lorentzian line shapes with less than 11 Hz full width. This linewidth is 70 times narrower than that in buffer gas filled cells used in commercial Rb atomic frequency standards. The phase shift per wall collision is 0.058 radians/collision as derived from an observed wall-induced hyperfine frequency shift of −52 Hz at a wall temperature of 26 °C.
28Si implantation into 40Ar implant-pretreated semi-insulating GaAs substrates—mobility and activation efficiency enhancement
Authors: Liu S. G. , Narayan S. Y. , Magee C. W. , Wu C. P.
Published: February 2003

We describe a 750-keV, 5–10×1012 cm−2 dose, 40Ar implant pretreatment for semi-insulating (SI) GaAs substrates allowing generation of 28Si implanted n layers with higher mobility and/or activation efficiency. This effect was observed in Bridgman Cr-doped, Bridgman Cr-O-doped, liquid encapsulated Czochralski (LEC) Cr-doped, and LEC undoped substrates. Pretreated and control samples were studied by carrier profiling, van der Pauw measurements, and secondary ion mass spectrometry (SIMS). The compensation ratio (ϑ = NA/ND) of n layers in pretreated substrates was lower than in controls. Probable mechanisms of improvement in ϑ are (1) reduced surface Cr concentration due to pretreatment, (2) preferential incorporation of 28Si on Ga sites due to pretreatment-created stoichiometry imbalance, and (3) a combination thereof.
Microsecond carrier lifetimes in Si films prepared on SiO2-coated Si substrates by zone-melting recrystallization and by subsequent epitaxial growth
Authors: Tsaur B-Y. , Fan John C. C. , Geis M. W.
Published: February 2003

The generation lifetimes in zone-melting-recrystallized Si films on SiO2-coated Si substrates and in epitaxial Si layers grown by chemical vapor deposition on the recrystallized films have been determined by pulsed metal-oxide-semiconductor (MOS) capacitor and p-n junction leakage current measurements. For recrystallized Si films that are 1×1017 cm−3 n type and 1×1016 cm−3 p type, respectively, the lifetimes are 0.2–0.5 μs and ∼1 μs. For epitaxial Si layers that are 2×1015 cm−3 n type, lifetimes are 0.8–1.3 μs, compared to ∼2 μs for control layers grown on single- crystal Si 〈100〉 wafers. The relatively high lifetimes suggest the possibility of fabricating bipolar devices utilizing Si-on-insulator structures prepared by the present techniques.
Parameter fluctuations and low frequency noise in Josephson junction devices
Authors: Tesche C. D.
Published: February 2003

A model is presented for a possible source of low frequency (1/f) noise in the dc superconducting quantum interferometer device (SQUID). Thermal fluctuations within the device are assumed to generate low frequency fluctuations in the device parameters. The resultant parameter fluctuations induce fluctuations in the device characteristics. As an example, low frequency voltage noise spectral densities are computed as a function of temperature and applied flux. In addition, low frequency variations in the forward transfer function of the SQUID are predicted. The model can be generalized to predict low frequency noise generated by parameter fluctuations in other Josephson junction circuits.
Poloidal flux loss in a field-reversed theta pinch
Authors: Hoffman Alan L. , Milroy Richard D. , Steinhauer Loren C.
Published: February 2003

Poloidal flux loss has been measured in field-reversed configurations and related to anomalous resistivity near the magnetic field null. The results indicate that mechanisms in addition to the lower hybrid drift instability are affecting transport.
A stress detection technique for stressed structures, including superconducting magnets
Authors: Tamada N. , Schauer F. , Iwasa Y.
Published: February 2003

It is demonstrated here that the resonant frequencies of a structure shift with stress in the structure. We propose to use this stress-induced shift in resonant frequency to monitor stressed structures such as superconducting magnets. Results observed from a large superconducting magnet are presented.
Stroboscopic microscopy of fast electro-optic switching in ferroelectric smectic C liquid crystals
Authors: Handschy M. A. , Clark Noel A.
Published: February 2003

We have characterized the process that yields high-speed, bistable, electro-optic switching in the surface-stabilized ferroelectric liquid crystal geometry, at intermediate electric fields. Switching proceeds by a continuous reversal of ferroelectric polarization in regions away from the surfaces of the sample, followed by the nucleation and growth of domains of reversed polarization in the remaining surface layers. A model involving bulk distortion+electrostatic+surface free energy successfully accounts for the variation of the switching process with changes in applied electric field.
Optical writing on blue, sputtered iridium oxide films
Authors: Bösch M. A. , Kang K. S. , Hackwood S. , Beni G. , Shay J. L.
Published: February 2003

Optical writing on sputtered iridium oxide films is reported. Optical changes on a 1-μm scale have been observed with a low-power helium neon laser. The basic writing mechanism is thermally induced dehydration at temperatures well below the melting point.
An efficient, small scale chemical oxygen-iodine laser
Authors: Bachar J. , Rosenwaks S.
Published: February 2003

More than 40% extractable power efficiency has been achieved in a transverse flow, small scale, chemically pumped iodine-atom laser. 5 W of cw laser emission at 1315 nm has been obtained via energy transfer from chemically generated O2(1Δ) to I atoms in a 10×1 cm2 rectangular flow duct. Simple construction materials, safely handled chemicals, and a medium size vacuum pump were used for fabricating and operating the laser. The importance of minimizing quenching of excited species by collision with water molecules or with the wall is demonstrated.
Picosecond surface Raman spectroscopy beyond the damage limit
Authors: Voss D. F. , Paddock C. A. , Miles R. B.
Published: February 2003

Picosecond Raman spectra of adsorbed CN were obtained for the first time in the presence of extensive surface damage. The incident laser intensity was 40 times than previously reported. At this intensity, nonlinear Raman spectroscopy such as coherent anti-Stokes Raman scattering should be feasible without dependence on surface enhancement.
Schottky barrier height measurement by electron-beam induced voltage
Authors: Huang H.-C. W. , Aliotta C. F. , Ho P. S.
Published: February 2003

We demonstrate that electron-beam induced voltage (EBIV) technique can be used for direct measurement of Schottky (or p-n junction) barrier height. Schottky barrier heights of PtSi, Pd2Si, and TiSi2 on n-type (111) Si measured by this technique were found to be 0.84, 0.74, and 0.57 eV, respectively, in excellent agreement with values obtained by the standard current-voltage technique. Because of no complication due to leakage current in EBIV measurement, this technique is particularly suited for studying the formation of low barrier height Schottky diodes. Furthermore, this technique can be extended for in situ measurements of barrier height to supplement surface electron spectroscopy studies on the electrical and chemical characteristics of silicide/Si interfaces.
Preparation of surface silicon nitride films by low energy ion implantation
Authors: Thomas G. E. , Beckers L. J. , Habraken F. H. P. M. , Kuiper A. E. T.
Published: February 2003

Surface silicon nitride layers have been formed on Si(100) crystals via high dose implantation of 1 keV N+ and 2 keV N+2 ions in ultrahigh vacuum. Auger electron spectroscopy depth profiles and Rutherford backscattering measurements indicate the formation of a relatively uniform layer having a composition near Si3N4 to a depth of approximately 70 Å. The current-voltage characteristics of such implanted layers are inferior to those of standard Si3N4 layers.
Observation of discrete current levels in metal-oxide-semiconductor field- effect transistors switched into weak inversion between 10 and 25 K
Authors: Tewksbury S. K.
Published: February 2003

A discrete conductance effect in the transient response of an n-channel metal-oxide- semiconductor field-effect transistor (MOSFET) switched from accumulation to weak surface inversion between 10 and 25 K is described. The discrete conductance appears as a set of equally spaced current levels superimposed on the steady state and transient currents. Transitions to lower discrete current levels are randomly distributed in time over the interval 0⩽t⩽τp(n), with τp(n) the maximum persistence time of the nth level and t = 0 the time when the MOSFET is switched into weak inversion. Up to six discrete levels have been observed. The general dependence of the current on biases and temperature is described.
Laser-induced lateral epitaxial growth of silicon over silicon dioxide with locally varied encapsulation
Authors: Sakurai J. , Kawamura S. , Nakano M. , Takagi M.
Published: February 2003

The effect and use of locally varied encapsulation thickness has been demonstrated in cw Ar laser- induced lateral epitaxial growth of silicon (Si) layers over silicon dioxide (SiO2) islands. The reflectivity of the laser light has been separately controlled in each region of the Si seed or the SiO2 island by changing the thicknesses of SiO2 and/or silicon nitride (Si3N4) caps. The technique essentially eliminates the surface ripples and thermal detachment of the laser-recrystallized Si layer, producing single crystalline layers over SiO2 islands as large as 15×80 μm and 20×40 μm.
A new method to control impact ionization rate ratio by spatial separation of avalanching carriers in multilayered heterostructures
Authors: Tanoue T. , Sakaki H.
Published: February 2003

We propose a new scheme to control the impact ionization rate ratio α/β of electrons and holes by utilizing multilayered heterostructures (–A–B–A–B–). In the structure, avalanching carriers, which accelerated mainly along the layer plane, are spatially separated by the action of band edge discontinuities in such a way that the impact ionization process of electrons takes place mainly in layer A and that of holes in layer B. An analysis is made to show that a proper choice of constituent materials allows the control of α/β over an extremely wide range (10−2∼103).
Direct evidence for the site of substitutional carbon impurity in GaAs
Authors: Theis W. M. , Bajaj K. K. , Litton C. W. , Spitzer W. G.
Published: February 2003

Direct evidence that substitutional carbon in GaAs is predominantly on the As sublattice is obtained from Fourier transform infrared spectroscopy absorption measurements of the carbon-induced localized vibrational mode (LVM). The previously reported LVM absorption band of carbon is measured under high resolution conditions and is found to be the near superposition of at least four bands. It is shown by comparison with similar measurements of silicon-doped GaAs and by physical arguments that the only satisfactory explanation is that the bands arise from carbon on As sites with different nearest-neighbor configurations of the two Ga isotopes. There is no experimental indication of carbon on the Ga sublattice. These are the first observations of such shifts in LVM spectra for simple substitutional impurity defects in semiconductors.
One-dimensional isentropic compression measurements of multiply loaded polymethylmethacrylate
Authors: Rosenberg Z. , Partom Y.
Published: February 2003

We present direct measurements of stress, strain, and temperature in multiply shocked polymethylmethacrylate (PMMA) discs. From these measurements we determine an approximation for the main compression isentrope of PMMA in the 0–16-GPa range. The experimental technique is based on embedding the three types of gauges (stress, strain, and temperature) in a thin PMMA disc and shock it in a series of up-going reverberations. We also show that from the measured temperature and strain increments one can calculate the volume dependence of the Grueneisen parameter in the relevant compression range.
Clausius–Mossotti-type approximation for elastic moduli of a three-dimensional, two-component composite
Authors: Kantor Yacov , Bergman David J.
Published: February 2003

A new approach to the problem of calculating the bulk elastic moduli of two-component composites with a specified microgeometry is applied to the problem of a 3-D system of circular-cylindrical inclusions with cubic symmetry. Explicit expressions, valid at least up to and including terms of order p2 (where p is the volume fraction of the inclusions), are obtained for the bulk compressibility and the two shear moduli. The approximation used, which is the leading order in a systematic expansion of the bulk moduli, is related to the Clausius–Mossotti approximation of electrostatics.
Pulsed excimer laser annealing of ion implanted silicon: Characterization and solar cell fabrication
Authors: Lowndes D. H. , Cleland J. W. , Christie W. H. , Eby R. E. , Jellison G. E. , Narayan J. , Westbrook R. D. , Wood R. F. , Nilson J. A. , Dass S. C.
Published: February 2003

A pulsed ultraviolet excimer laser (XeCl, 308-nm wavelength, ∼41-ns pulse duration) has been sucessfully used for laser annealing of both boron- and arsenic-implanted silicon, and for formation of high quality p-n junctions. Transmission electron microscopy, secondary ion mass spectroscopy, and sheet electrical properties measurements are used to characterize ion implanted and XeCl laser annealed specimens. Predictions of thermal melting model calculations of the annealing process are also compared with results of these measurements. Finally, we demonstrate the first use of high repetition rate, scanned, overlapping excimer laser pulses to fabricate large area photovoltaic solar cells with good performance characteristics.
Very narrow graded-barrier single quantum well lasers grown by metalorganic chemical vapor deposition
Authors: Kasemset D. , Hong C. S. , Patel N. B. , Dapkus P. D.
Published: February 2003

Graded-barrier GaAs-GaAlAs single quantum well lasers have been fabricated, utilizing the graded-index separate confinement heterostructure to confine carriers and optical field. Very low threshold current densities have been observed down to a well size of 75 Å. The lowest threshold current density observed is 240 A/cm2 for a 100-Å heavily doped quantum well laser. This experimental value agrees very well with the calculated threshold current density obtained from detailed band calculation and is attributed to the enhanced gain-current characteristic in these quantum well structures.
Meaning of the photovoltaic band gap for amorphous semiconductors
Authors: Yablonovitch E. , Tiedje T. , Witzke H.
Published: February 2003

We introduce the concept of a photovoltaic band gap Epvg for amorphous solar cells. This is the minimum photon energy thermodynamically required for the generation, of two free carriers in an operating solar cell. For hydrogenated amorphous silicon the photovoltaic band gap is 1.57 eV at 1-sun illumination.
Electron irradiation induced deep levels in p-InP
Authors: Sibille A. , Bourgoin J. C.
Published: February 2003

Room-temperature 1-MeV electron irradiations have been performed on p-type epitaxial InP and the induced defects have been investigated by deep level transient spectroscopy in the range 90–300 K. Five hole traps created by the irradiations were detected, corresponding to a total introduction rate of ∼1 cm−1, much higher than what had been found in n-InP. The dominant traps anneal out at 360–410 K.
Epitaxial growth of Fe on GaAs by metalorganic chemical vapor deposition in ultrahigh vacuum
Authors: Kaplan R. , Bottka N.
Published: February 2003

Fe epitaxial films have been grown on GaAs(100) by thermal dissociation of Fe (CO)5 in a high vacuum environment. In situ low-energy electron diffraction (LEED) and Auger spectroscopy have been used to study the MOCVD process and to characterize the growing films. Excellent film quality is evidenced by the observed small ferromagnetic resonance linewidth.
Current oscillations in semi-insulating GaAs associated with field-enhanced capture of electrons by the major deep donor EL2
Authors: Kaminska M. , Parsey J. M. , Lagowski J. , Gatos H. C.
Published: February 2003

Current oscillations thermally activated by the release of electrons from deep levels in undoped semi-insulating GaAs were observed for the first time. They were attributed to electric field-enhanced capture of electrons by the dominant deep donor EL2 (antisite AsGa defect). This enhanced capture is due to the configurational energy barrier of EL2, which is readily penetrated by hot electrons.
Evidence for Auger and free-carrier losses in GaInAsP/InP lasers: Spectroscopy of a short wavelength emission
Authors: Mozer A. , Romanek K. M. , Schmid W. , Pilkuhn M. H. , Schlosser E.
Published: February 2003

We report the observation of two high-energy emission bands near 1.31 eV in Ga0.29In0.71As0.61P0.39 /InP laser diodes. One emission band is associated with recombination in the InP due to carrier leakage from the active layer. A second, more important emission band with an energy close to E0+Δ0 is associated with recombination of holes in the split-off valence band and electrons in the conduction band. The split-off valence band is significantly populated by Auger recombination and intervalence band absorption. From the dependence of the integrated E0+Δ0 luminescence intensity on injection current (below threshold) we determine an Auger coefficient for holes of C≂5×10−29 cm6 s−1 at T=300 K.
Lateral zone growth and characterization of device quality silicon-on-insulator wafers
Authors: Lam H. W. , Pinizzotto R. F. , Malhi S. D. S. , Vaandrager B. L.
Published: February 2003

A lateral zone melting process has been developed whereby (100) silicon-on-insulator wafers can be obtained. Small angle grain boundaries exist extensively in the recrystallized silicon, with a maximum variation in the orientation between adjacent grains of 0.3°. A SiC coating prevents the dusting of carbon from the moving heater from contaminating the silicon film. It has been found that enhanced arsenic diffusion along the small angle grain boundaries in this material is significantly less than that in the grain boundaries in laser-recrystallized silicon-on-insulator material. Furthermore, it was found that the small angle grain boundaries do not significantly affect the carrier mobility, probably because of the relatively low surface trapping state density at the small angle grain boundaries. Complementary-metal-oxide-semiconductor devices fabricated in this material exhibit characteristics that are comparable to those of bulk devices.
Characterization of seeded-lateral epitaxial layer by microprobe reflection high-energy electron diffraction
Authors: Ohkura M. , Ichikawa M. , Miyao M. , Tokuyama T.
Published: February 2003

The crystallinity and regrowth mechanism of a seeded-lateral epitaxial layer of Si on a SiO2 substrate is evaluated using a newly developed microprobe reflection high-energy electron diffraction method. Measurements with a spatial resolution of 0.1 μm reveal that the lateral seeding process actually occurs in the regrowth process and that the seeding area is indispensable to the process, though a seed length of less than 0.5 μm is required.
New fabrication process for Josephson tunnel junctions with (niobium nitride, niobium) double-layered electrodes
Authors: Shoji Akira , Shinoki Fujitoshi , Kosaka Shin , Aoyagi Masahiro , Hayakawa Hisao
Published: February 2003

All hard Josephson tunnel junctions, whose base and counter electrodes are composed of double-layered niobium nitride (NbN) and niobium (Nb) films, have been successfully fabricated by isolating a junction sandwich formed on a whole silicon wafer with a reactive ion etching technique. The reactive ion etching technique has been used for patterning both base and counterelectrodes, and self-aligning definition of junction areas has been performed. The fabricated junctions show good quality single-particle tunneling characteristics and excellent uniformity in critical currents.
Picosecond, tunable ArF* excimer laser source
Authors: Egger H. , Luk T. S. , Boyer K. , Muller D. F. , Pummer H. , Srinivasan T. , Rhodes C. K.
Published: February 2003

A 40-mJ ArF* laser with pulse duration ∼10 ps and spatial and spectral properties close to the transform limits is described. Substantial extraction of the available energy from the final amplifier is demonstrated, a fact providing direct evidence against the presence of significant nonlinear losses in the amplifying medium up to an intensity of ∼1 GW/cm.2
Electrical properties of donor and acceptor implanted Hg1−xCdxTe following cw CO2 laser annealing
Authors: Bahir G. , Kalish R. , Nemirovsky Y.
Published: February 2003

The electrical properties of P and B implanted and cw CO2 laser annealed n- and p-type Hg1−x CdxTe (x=0.21, 0.29) are studied. Hall, conductivity, and capacitance-voltage (C-V) measurements carried out on the virgin, implanted, and annealed samples all show that both donor and acceptor implants can be electrically activated when annealing with a cw CO2 laser (0.3 s, 250 W/cm2) is employed.
Far-infrared surface plasmon coupling with overcoated gratings
Authors: Seymour R. J. , Koteles E. S. , Stegeman G. I.
Published: February 2003

Calculated and experimental results are presented for coupling bulk electromagnetic waves to surface electromagnetic waves using overcoated gratings at 118.8 μ. A coupling efficiency of 8.7% is reported.
Pseudo-optical absorption spectra in HgCl2 and HgBr2 from 4 to 14 eV
Authors: Spence David , Wang R.-G. , Dillon M. A.
Published: February 2003

Using a high-resolution electron-impact energy-loss spectrometer we have measured the energy-loss spectra of electrons scattered near the forward direction from HgCl2 and HgBr2, for incident energies of 200 eV and energy-loss between 4 and 14 eV. Under these conditions the energy-loss spectra correspond closely to optical-absorption spectra. In addition to the well known 1Πu and 1∑+u absorption bands, we observe many new energy-loss processes beginning at 7.9 eV in HgBr2 and 8.60 eV in HgCl2. The relative cross sections and energies of these processes are in excellent agreement with those inferred as being necessary to account for discharge and fluorescence measurements in e-beam sustained mercuric bromide lasers.
Bistability observed in a Fabry–Perot interferometer with quadratic nonlinear medium
Authors: Wedding Berthold , Jäger Dieter
Published: February 2003

Bistability due to a second-order dispersive nonlinearity in a Fabry–Perot resonator is studied. The experiments are performed on a nonlinear transmission line resonator. Nonlinear resonance curves, bistability as well as instabilities, and the generation of harmonics are observed. The theoretical treatment of bistability is based upon a nonlinear dispersion relation as derived from an inspection of two interacting harmonics or, in a second approach, of propagating solitons.
Charge transient spectroscopy
Authors: Farmer J. W. , Lamp C. D. , Meese J. M.
Published: February 2003

A new variation of the deep level transient spectroscopy technique is presented. In the new approach, the current transient is integrated, yielding a charge transient. A simple circuit for integrating the current is given and is analyzed. The charge transient technique is compared to previous capacitance transient and current transient techniques, and the advantages of the new method are discussed. The effects of diode leakage currents are also analyzed. Data are presented for defects in neutron irradiated Si.
High-field electron transport in InxGa1−xAsyP1−y (λg =1.2 μm)
Authors: Windhorn T. H. , Cook L. W. , Stillman G. E.
Published: February 2003

A fixed-frequency microwave time-of-flight technique has been used to measure electron drift velocities in Inx Ga1−x Asy P1−y (λg =1.2 μm) at temperatures 95–400 K and electric field strengths of up to 200 kV/cm. The room-temperature electron drift velocity in the quaternary is equal to the velocity in GaAs for field strengths greater than ∼62 kV/cm, but the velocity is higher in the quaternary for field strengths from about 20–62 kV/cm at 300 K. At temperatures above 300 K the high-field velocity is larger in the quaternary than in GaAs, but below 300 K the high-field velocity is larger in GaAs.
Growth of InGaAsP by molecular beam epitaxy
Authors: Holah G. D. , Eisele F. L. , Meeks E. L. , Cox N. W.
Published: February 2003

Molecular beam epitaxy has been used to grow good quality films of InGaAsP on InP substrates. The films have been characterized using infrared absorption, electroreflectance, x-ray diffraction, reflection electron diffraction, and Hall measurements. Lattice matching was achieved and room-temperature mobilities up to 4600 cm2 V−1 s−1 were measured.
Index of refraction dispersion of n- and p-type InP between 0.95 and 2.0 eV
Authors: Stone J. , Whalen M. S.
Published: February 2003

The index of refraction dispersion of InP has been measured by a normal incidence reflection method. The index of refraction is proportional to the reflected power with a small correction necessary for absorption. Spectra are reported for one p-type and several n-type crystals, and are fitted with single-oscillator Sellmeier curves below the band-gap energy.
Motion of deep gold-related centers in reverse-biased silicon junction diodes at room temperature
Authors: Pearton S. J. , Tavendale A. J.
Published: February 2003

The room-temperature motion of gold-related centers in reverse-biased silicon n+p junction diodes has been observed using deep level transient spectroscopy. The concentration profile of the gold-related donor level (Ev +0.34 eV) is presented as a function of the duration of the electric field application. A mobility of 7.8±3.2×10−15 cm2 V−1 s−1 at 25 °C was obtained for this center. Under the same conditions, no movement was observed of the deep gold-related acceptor center (Ec −0.55 eV) in n-type silicon surface barrier diodes.
Phase-matched light amplification by three-wave mixing process in a birefringent fiber due to externally applied stress
Authors: Ohashi Masaharu , Kitayama Ken-ichi , Ishida Yukinori , Uchida Naoya
Published: February 2003

A novel method to achieve phase-matched light amplification in a birefringent fiber via the three-wave mixing is proposed by using frequency shift change due to the stress applied to the fiber. It is confirmed that the signal power from a cw laser diode at λ=1.292 μm is amplified by 6.1×103 times in the birefringent fiber pumped with a Q-switched Nd: yttrium aluminum garnet laser at λ=1.064 μm. This will provide a new fiber-optic light signal amplifier having a good tolerance for variation of signal wavelengths.
Focusing of a 7700-Å high power phased array semiconductor laser
Authors: Scifres D. R. , Sprague R. A. , Streifer W. , Burnham R. D.
Published: February 2003

A high power (200 mW/facet) phased array semiconductor injection laser consisting of multiple optically coupled 7700-Å emitters is focused to obtain over 90 mW in a single nearly diffraction limited 2.5-μm-diam spot. Focusing is accomplished by imaging the vertical near-field and the lateral far-field patterns. Such an optical system functions only when the emitters are mutually coherent, as with this device.
Precision measurement of Rayleigh wave velocity perturbation
Authors: Liang K. , Bennett S. D. , Khuri-Yakub B. T. , Kino G. S.
Published: February 2003

A 50-MHz acoustic microscope for imaging Rayleigh wave velocity perturbation over a surface is described. A line scan of a multiple-thickness indium film deposited on a glass shows that the system has a potential sensitivity of 1 part in 105 change in velocity.
Discrete Fourier transformation using a time-integrating, acousto-optical signal processor
Authors: Lee John N. , Lin Shih-Chun , Tveten A. B.
Published: February 2003

Discrete Fourier transformation has been implemented on a time-integrating, acousto-optical signal processor based on the chirp z-transform algorithm. Novel features are the use of an injection diode laser for signal input and an additive architecture. The operational principles are analytically derived and experimentally demonstrated. Discrete Fourier transforms of 4, 8, 64, and 128 points are in excellent agreement with fast Fourier transform simulations. The architecture lends itself easily to miniaturization and to extension to parallel, multichannel operation.
Integrated optical temperature sensor
Authors: Johnson L. M. , Leonberger F. J. , Pratt G. W.
Published: February 2003

An integrated optical temperature sensor requiring no electrical connection and consisting of a parallel array of unequal arm-length waveguide interferometers in LiNbO3 has been designed and the key components have been demonstrated. The optical transmission of each interferometer varies sinusoidally with temperature with a period inversely proportional to the path length difference between the two arms. This device has a projected range and resolution of ≳700 °C and 2×10−3 °C, respectively, and would be particularly useful in applications requiring immunity to electrical noise.
Microbend optical fiber tapped delay line for gigahertz signal processing
Authors: Jackson K. P. , Bowers J. E. , Newton S. A. , Cutler C. C.
Published: February 2003

A single-mode optical fiber tapped delay line which utilizes microbend taps has been constructed. The taps are obtained simply and repeatably and are uniform to ±1 dB. A device with 19 taps and a 1-ns delay between taps was constructed. The average tap strength was 1.5%. The frequency response for the device has been measured and simple programmability has also been demonstrated. Extension of the procedure to devices with 102–103 taps and 100-ps time delays is possible.
Thermoelectricity in composition-modulated Cu-Ni foils
Authors: Baral D. , Hilliard J. E.
Published: February 2003

Anomalous thermoelectric behavior has been observed in composition-modulated Cu-Ni foils. A maximum in the thermo-emf and its temperature differential was observed at a modulation wavelength of approximately 2.0 nm at which a maximum in the elastic modulus has also been observed.
Electron-beam induced current in GaAs field-effect transistors
Authors: Newman D. S. , Ferry D. K.
Published: February 2003

We have used an electron beam to probe the active region of n-channel GaAs junction field-effect transistors. The injected charge leads to a rise in drain current (ΔiD), and static current gains (ΔiD / ΔiB) in excess of 107 are observed. These gains are ∼104 greater than expected from pair production given the incident beam energy (15 kV). It has been previously suggested that the injected charge modifies the surface potential, but we find the major effect to be an effective channel thickness increase. In addition, this channel opening and the current gain saturate at high beam current.
Mid-infrared lasers in hydrogen and deuterium
Authors: Barr T. A. , McKnight W. B.
Published: February 2003

New laser lines at 3.71 and 3.84 μm in hydrogen and lines at 4.52, 4.60, and 4.71 μm in deuterium excited by a pulsed electrical discharge have been obtained. The lines in hydrogen are assigned to the a 3Σ+g → c 3Πu triplet band, but the lines in deuterium have not yet been assigned. Direct electronic excitation from the ground state to the a 3Σ+g state is believed to be the excitation mechanism, and indicates that an excimer-type laser from the a 3Σ+g upper state to the dissociative b 3Σ+u state may be possible.
Superconducting quantum interference device with very low magnetic flux noise energy
Authors: Van Harlingen D. J. , Koch Roger H. , Clarke John
Published: February 2003

We have fabricated dc superconducting quantum interference devices incorporating Josephson tunnel junctions with an inductance of about 2 pH and a capacitance per junction of about 0.3 pF. The lowest measured flux noise energy was 3.2 h/ at 1.4 K at a frequency of 202 kHz. When the 1/f noise was subtracted, the white noise energy decreased from around 3h/ at 4.2 K to below 2h/ at 1.4 K.
A15 Nb3(AlGe) superconductors prepared by transformation from liquid quenched body-centered cubic phase
Authors: Togano K. , Takeuchi T. , Tachikawa K.
Published: February 2003

A supersaturated body-centered cubic (bcc) solid solution of Nb3(Al1−xGex) up to x = 0.3 has been prepared by the liquid quenching on a hot Cu substrate. The quenched materials are then transformed to the A15 structure by annealing above 800 °C. Following the transformation, the critical temperature rises above 18 °K. The A15 phase converted from the bcc phase has an extremely small grain size of a few hundred angstroms, resulting in a high critical current density Jc in high magnetic fields. Jc of 3.5×105 A/cm2 at 4.2 °K and 16 T has been achieved in the Nb3(Al0.8Ge0.2) sample annealed at 850 °C for 7 h.
Palladium-surface acoustic wave interaction for hydrogen detection
Authors: D’Amico A. , Palma A. , Verona E.
Published: February 2003

A hydrogen sensitive detection technique utilizing a surface acoustic wave (SAW) delay line coated with a palladium thin film is presented. The hydrogen-palladium interaction produces a change in the velocity of SAW propagating on the coated substrate, which is detected as phase shift at the output of the delay line. Presently, hydrogen concentrations as small as 50 ppm in a flowing H2+N2 mixture have been detected.