bluuebunny/crossref_metadata_2025 huggingface dataset:
Planar-type self-magnetically-insulated diode as a new source of intense pulsed light-ion beam
Authors: Yoshikawa T. , Masugata K. , Ito M. , Matsui M. , Yatsui K.
Published: February 2003

A new type of ion diode named the ‘‘Planar-Type Self-Magnetically-Insulated Diode’’ is developed. Good efficiency of ion production (∼30%) is obtained with good reproducibility. A multiple-shot operation (40 shots or even more) is possible with relatively high power (900 kV, 180 kA). Surface flashover of the anode is affected by an initial irradiation of lower-energy electrons of the incident voltage pulse.
A new type of corona-discharge photoionization source for gas lasers
Authors: Marchetti R. , Penco E. , Salvetti G.
Published: February 2003

We present results of an experimental study aimed at characterizing a new type of corona-discharge photon source, which is particularly suitable to be used as preionizer in transversely excited gas lasers operating at high pulse repetition frequencies. Results of comparative tests carried out in CO2 laser gas mixtures between this photoionization source and a conventional bare spark source are also reported, showing the superiority of the proposed scheme.
Momentum equation for arc-driven rail guns
Authors: Batteh Jad H.
Published: February 2003

In several models of arc-driven rail guns, the rails are assumed to be infinitely high to simplify the calculation of the electromagnetic fields which appear in the momentum equation for the arc. This assumption leads to overestimates of the arc pressures and accelerations by approximately a factor of 2 for typical rail-gun geometries. In this paper, we develop a simple method for modifying the momentum equation to account for the effect of finite-height rails on the performance of the rail gun and the properties of the arc. The modification is based on an integration of the Lorentz force across the arc cross section at each axial location in the arc. Application of this technique suggests that, for typical rail-gun geometries and moderately long arcs, the momentum equation appropriate for infinite-height rails can be retained provided that the magnetic pressure term in the equation is scaled by a factor which depends on the effective inductance of the gun. The analysis also indicates that the magnetic pressure gradient actually changes sign near the arc/projectile boundary because of the magnetic fields associated with the arc current.
Twin channel laser with high cw power and low beam divergence
Authors: Figueroa L. , Morrison C. , Law H. D. , Goodwin F.
Published: February 2003

We report on a new GaAlAs/GaAs semiconductor laser, the Twin Channel Laser, consisting of two closely spaced channel substrate planer (CSP)-type lasers having high cw power (50–80 mW), high differential efficiency (45–55%), low beam divergence (4–6° by 25°), almost single longitudinal mode operation at high output power (50 mW), and high T0 (180°< T0 < 200°). The favorable output characteristics are related to the strong coupling between the individual emitters which is a consequence of the large optical gain between the emitters.
Observation of ablatively accelerated thin foils by x-ray backlighting at 0.35-μm laser wavelength
Authors: Daido H. , Nishimura H. , Tateyama R. , Ogura K. , Nakai S. , Yamanaka C.
Published: February 2003

The x-ray backlighting technique is a very important technique for the investigation of laser-imploded target dynamics. We examined the problem of x-ray opacity for shadowgraphy, which depends both on the x-ray source and the accelerated material. Ablatively accelerated Al foil targets were observed by x-ray backlighting with either an Al or Cu source. The large difference of the results indicates the importance of source selection for a meaningful interpretation of the results.
Thermal stabilities of amorphous and crystalline TiCuHx
Authors: Bowman R. C. , Furlan R. J. , Cantrell J. S. , Maeland A. J.
Published: February 2003

The irreversible transitions of the glassy alloy a-TiCu as well as the crystalline and amorphous ternary hydrides TiCuHx were studied by differential scanning calorimetry and x-ray diffraction. While the exothermic transition peaks and kinetic activation energies are closely correlated, the heats of transitions do not follow the same trends as the transition temperatures. The thermal stability of a-TiCuH1.41 is much less than the stabilities of either a-TiCu or c-TiCuH0.96. This behavior is attributed to greater atomic diffusivities in the amorphous hydride.
Rapid annealing of titanium silicide using a graphite strip heater
Authors: Jones R. E. , Li B. Z. , Daneshvar K. , Davis J.
Published: February 2003

Titanium silicide films cosputtered on a polycrystalline silicon layer over a thermally oxidized silicon wafer were rapidly annealed at various temperatures and times using a graphite strip heater. Sheet resistances comparable with those of furnace annealed samples were obtained using 45-sec anneals at 1000–1200 °C. X-ray diffraction revealed only the formation of a TiSi2 phase, but Rutherford backscattering showed that the amount of excess silicon beyond stoichiometric TiSi2 increased with increasing anneal temperature. Significant increases in the infrared reflectivity spectrum were observed upon annealing which suggests that front side annealing may result in better thermal uniformity across a wafer.
Anisotropy, magnetic field, and stress influences on the phase transitions of spin-flop-type antiferromagnets
Authors: Machado Sydney F. , Tsallis Constantino
Published: February 2003

We discuss, within a mean field approximation, the influences of anisotropy (in the spin space) and external uniaxial stress on the Heisenberg antiferromagnet in the presence of magnetic field. The phase diagram evolution (as function of anisotropy and stress) which is obtained enables a satisfactory overall interpretation of recent experiments on Mn(Br1−xClx)2⋅4H2O, K2[FeCl5(H2O)], CoCl2⋅6H2O, and (C2H5NH3)2CuCl4.
Electron paramagnetic resonance spectroscopy of fast neutron-generated defects in GaAs
Authors: Goltzene A. , Meyer B. , Schwab C. , Greenbaum S. G. , Wagner R. J. , Kennedy T. A.
Published: February 2003

A series of fast neutron-irradiated GaAs samples (neutron fluence range of 2×1015–2.5×1017 cm−2) has been investigated by electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra at 9 GHz exhibit a broad (∼1 kG) Lorentzian singlet at g≊2.09 superimposed on the AsGa quadruplet. The singlet intensity scales linearly with neutron fluence as does that of the quadruplet. The presence of this new defect has not been reported in as-grown GaAs known to have large concentrations of AsGa defects. EPR measurements at 35, 159, and 337 GHz indicate that the singlet linewidth increases with the microwave frequency.
Surface accumulation of manganese in Si+-implanted and annealed semi-insulating indium phosphide
Authors: Rao E. V. K. , Duhamel N. , Gauneau M.
Published: February 2003

Using low-temperature photoluminescence and secondary ion mass spectrometry measurements, we show here that Mn, a residual impurity, accumulates in a region close to the sample surface in Si+- but not in Ar+-implanted and close contact annealed bulk semi-insulating (SI) InP(Fe). These results which constitute a first observation on the influence of the electrical nature of the species implanted in InP are tentatively explained using a simple model based on the amphoteric nature of Mn (substitutional and interstitial) and the electric field due to the charge distribution of the implanted impurities.
Near band-gap photoluminescence from sulfur-doped silicon samples
Authors: Weber J. , Holm C.
Published: February 2003

Photoluminescence measurements in sulfur-doped silicon samples reveal new luminescence lines at 1.1439 eV (S1), 1.1150 eV (S2), and 1.0858 eV (S1TO). [S1TO is the transverse optical (TO) phonon replica of the S1 line.] The sharp luminescence lines result from the recombination of excitons bound to two different centers. The S1 line was found to have a thermal ionization energy of 12.0 meV, which corresponds directly to the spectroscopically determined binding energy of the bound exciton. A correlation of the binding centers with the sulfur donor levels is suggested.
Comment on ‘‘Threshold switching in chalcogenide-glass thin films’’
Authors: Chiang Chun
Published: February 2003

D. Adler, M. S. Shur, M. Silver, and S. R. Ovshinsky [J. Appl. Phys. 51, 3289 (1980)] propose that field-induced filling of traps may lead to S-shaped negative differential conductance (SNDC), and use the existence of two solutions of electron concentration for a given applied field as evidence for it. We comment on the conditions for this existence of two solutions and its significance to the SNDC.
Excimer laser projection photoetching
Authors: Latta M. , Moore R. , Rice S. , Jain K.
Published: February 2003

Direct photoetching of various resists and polymers with a 193-nm ArF excimer laser has been demonstrated by imaging a mask through a projection lens. Feature sizes ranging from 2 to 20 μm have been cleanly etched in 1-μm-thick films.
Role of stress on the parabolic kinetic constant for dry silicon oxidation
Authors: Fargeix A. , Ghibaudo G.
Published: February 2003

This paper is concerned with the temperature dependence of the parabolic kinetic constant Kp for dry oxidation of silicon. Based on the stress stated model of oxidation, an explanation of the change with temperature of the activation energy of Kp, as well as of the diffusivity decaying near the Si-SiO2 interface, is presented by considering the temperature-dependent free energy change due to stress relaxation during growth. The results are favorably compared to dry oxidation data. Moreover, the maximum stress at the Si-SiO2 interface found on the order of 4×1010 dyn/cm2 is consistent with experimental data of stress measurements.
Impurity effects of the 3d transition metal atoms on the first-order magnetic and electrical transition in NiS
Authors: Futami T. , Anzai S.
Published: February 2003

In the NiAs-type Ni1−xMxS (M: the 3d transition metal impurities), the solubility limits xL are determined to be 0.077±0.005 for M:Ti, 0.04±0.01 for M:Cr, 0.001±0.002 for M:Mn, 0.060±0.005 for M:Co, and 0.015±0.005 for M:Cu. The first-order transition temperature Tt (between the antiferromagnetic less-conductive and the Pauli-paramagnetic high-conductive states) is investigated as a function of x for M:Ti, Cr, Co, and Cu (as described on M:V in our previous paper). The lattice parameters c and a are also investigated. The larger x gives the lower Tt for these M, except in the lower x for M:V or Cr. The following features are found on M:Ti (similar to V and Cr): a Curie–Weiss-type susceptibility is superimposed on the constant Pauli-paramagnetic one in temperatures above Tt; the sign of dθ(T<Tt)/dT (θ: thermoelectric motive force) changes from plus to minus at a critical concentration. The ratio c/a hardly depends on x in the cases of more than half filled M (Co and Cu), while it increases in x in the less than half filled M (Ti, V, and Cr). Correlations between these experimental results and the nuclear charges of M atoms or the exchange splitting energies of M(3s) bands in MS compounds are discussed on the basis of the Friedel-type dilute-alloy model. It is additionally noted that Ni0.96Co0.04S exhibits an anomalous temperature behavior of susceptibility just above Tt. This behavior indicates the presence of an intermediate state, between the above two magnetic states, in the high x region for M:Co.
Effect of photocarrier spreading on the photoluminescence of double heterostructure material
Authors: Degani J. , Wilt D. P. , Besomi P.
Published: February 2003

Lateral spreading of photoexcited carriers can suppress the photoluminescence signal from double heterostructure wafers containing a p-n junction independently from saturable defects in the material. Experimental results are presented and a theory is derived to show that in any double heterostructure with a p-n junction the photoluminescence is suppressed if the power of the excitation source does not exceed a threshold value. The threshold power has been calculated in terms of material parameters, in excellent agreement with experimental results. This effect is the basis of a novel technique used for a nondestructive optical determination of the p-clad layer sheet conductance as well as junction misplacement in double heterostructures, both of which are important parameters for injection lasers.
Infrared radiation annealing for extended-defect reduction in As-implanted Si crystals
Authors: Komatsu Ryosaku , Kajiyama Kenji
Published: February 2003

Infrared radiation annealing (IRA) has been used to remarkably reduce extended defects in As-implanted Si. In the present work, As+ was implanted into a 76-mm-diam (111) Si wafer at a 5×1015/cm2 dose and 25-keV energy. The sample had a Si outer ring and was uniformly heated by means of IR at 1340 °C for 10 min in a dry-O2 ambient; about 0.05 μm of the Si was oxidized. In the epitaxial layer on the annealed sample, the etch-pit density was lower than 102/cm2. Contrarily, the etch-pit density rose above 108/cm2 when the implantation energy was increased, annealing temperature decreased, or the oxidation thickness decreased. The IRA described here is effective in annealing high-dose samples, such as in applications involving buried collectors in n-p-n transistors.
Conditions for stability of bubble nuclei in solid surfaces contacting a liquid-gas solution
Authors: Ward C. A. , Levart Eugene
Published: February 2003

We first consider the conditions under which pockets of a gaseous phase, i.e., bubble nuclei, would be in stable equilibrium in the roughness of the walls of a container of liquid-gas solution or in the walls of small, solid particles suspended in the liquid phase. It is shown that if there are a sufficient number of such nuclei, then in an arbitrarily large, closed volume of solution maintained at constant temperature and pressure, these tiny bubble nuclei can be in a thermodynamically stable equilibrium state when the gas concentration in the liquid phase is only slightly greater than the equilibrium value and the contact angle is small. The conditions under which these bubble nuclei result in the appearance of macroscopic bubbles is then considered. It is shown that small superheats would result in macroscopic bubble appearance in such a system. Physically, the stable equilibrium state of the bubble nuclei results from the mutual competition of the bubble nuclei for the dissolved gas of the liquid phase.
Mode conversion of obliquely incident guided magnetic waves by a grating on a yttrium iron garnet film for the normal magnetization
Authors: Seshadri S. R. , Tsai Ming-Chi
Published: February 2003

The partial differential equations governing the transport of the slowly varying amplitudes of the interacting guided magnetic waves supported by a yttrium iron garnet film having a periodic array of shallow grooves on one of its surfaces are deduced using quasioptical techniques for the case in which the magnetization is normal to the midplane of the film and the wave vectors are inclined to the grating vector. For the periodic array extending only for a finite length along the film, the longitudinal boundary value problem is solved for an incident-plane guided magnetic wave to obtain the reflection, the transmission, and the absorption coefficients. The important characteristics of the reflection coefficient are examined and the various dephasing effects on the reflection characteristics are investigated.
Depletion layer formation rate at T<30 °K in buried channel, metal-oxide-semiconductor transistors
Authors: Tewksbury S. K. , Biazzo M. R. , Lindstrom T. L. , Tennant D. M.
Published: February 2003

Measurements of depletion layer formation rates in buried channel silicon, metal-oxide-semiconductor devices at carrier freeze-out temperatures are presented. The procedure is based on the current injected into the gate region by a pulsed gate bias and the dependence of this injection current on the pulse frequency. This method avoids strong electric field effects (field-enhanced emission) and a response due to surface state trapping. In addition to describing a new dynamic response effect in metal-oxide-semiconductor transistors at low temperatures, the measured activation energy of the arsenic dopant is found to be 54.2 meV, in close agreement with the accepted ionization energy.
Photovoltage profiling of hydrogenated amorphous Si solar cells
Authors: Szostak D. J. , Goldstein B.
Published: February 2003

We have used Surface Photovoltage Profiling (SPVP) to study hydrogenated amorphous Si (a-Si:H) p-i-n solar cells grown on glass/conductive-transparent oxide (CTO) or stainless-steel substrates. This technique involves the measurement by a Kelvin Probe of photoinduced changes in the surface potential with respect to a fixed back contact as tha cahh is layers of a-Si:H are consistent with these interface voltages. The junctions of the solar cell are analyzed in terms of their barrier heights (obtained by measuring Δφ at very high illumination levels at low temperature), their depletion widths (obtained from the photovoltage profiling), and their space-charge densities (estimated from published density-of-states curves). The principal reasons for poor cells were found to be: (1) poor i/n junction photovoltages, and (2) the presence of a low- or zero-field region in the i layer, caused primarily by high space-charge densities and correspondingly narrow depletion widths, leading to poor minority carrier current collection and fill factor. Similar low- or zero-field regions can also exist in cells of very good quality (efficiency ∼10%), but their harmful effects can be compensated for by higher diffusion lengths. Such zero-field regions may also play a pivotal role in the optically induced degradation of a-Si:H solar cells; we have found that in an unstable cell prolonged illumination can produce a fivefold increase in space-charge density above that before illumination, with a concommitant decrease in p/i junction depeletion width.
Photon effect on electron-irradiated boron-doped silicon solar cell
Authors: Roux Michel , Bernard Jacques , Reulet René , Crabb Roy L.
Published: February 2003

The correlation between current-voltage characteristics measurements and deep level transient spectroscopy data on boron-doped silicon solar cells irradiated at room temperature by 1-MeV electron beam, followed or not by an illumination, is presented in this study. From such correlation, it is possible to conclude that the additional degradation induced by the light is due to the appearance of a defect in oxygen-lean silicon, which should be associated with the vacancy-oxygen-carbon complex [V-O-C]. A model, based upon the dissociation, enhanced by capture of photogenerated carriers, of the interstitial boron–interstitial oxygen complex, accounts for these observations: it verifies that the ‘‘photon effect’’ exists in oxygen-lean cells and is absent in high oxygen concentration cells.
Organic-on-inorganic semiconductor contact barrier diodes. II. Dependence on organic film and metal contact properties
Authors: Forrest S. R. , Kaplan M. L. , Schmidt P. H.
Published: February 2003

We discuss the effects of organic film thickness, film crystalline texture, contact metal, and temperature on the current-voltage characteristics (I-V) of organic-on-inorganic (OI) semiconductor contact barrier diodes, where the prototypical compound; 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) serves as the organic thin film. The results presented can be fully understood in terms of the thermionic emission-space-charge-limited (TE-SCL) current model introduced in previous papers. Studies of the I-V characteristics suggest the presence of a trap distribution centered at Δε=0.20 eV above the PTCDA valence band edge. Also, we have found a correlation between the hole mobility (μeff) and PTCDA crystalline texture, and obtain a mobility as high as μeff=1.4 cm2/V s for highly ordered crystalline thin films. Finally, the general criteria which must be fulfilled by an organic compound used to achieve high-performance OI devices are outlined. The properties of several such devices using various organic thin films are described.
Gauge factor of manganin under uniaxial stress conditions
Authors: Partom Y. , Rosenberg Z. , Keren B.
Published: February 2003

In order to enhance our understanding of the piezoresistance behavior of manganin gauges we performed a static calibration test in which we measured the resistance change of a commercial gauge under uniaxial stress conditions. We present a detailed calculation in which we show that the gauge behavior can be predicted very well by using calibration data from different experiments under different loading conditions like uniaxial strain and hydrostatic compression.
Decay of the electron-beam-induced current in hydrogenated amorphous silicon devices
Authors: Yacobi B. G. , Herrington C. R. , Matson R. J.
Published: February 2003

Decay of the electron-beam-induced current in hydrogenated amorphous silicon devices at continuous electron irradiation is investigated as a function of both the electron-beam energy and current. The decay mechanism is based on the formation of electron-irradiation-induced microscopic defects that act as recombination centers and reduce the lifetime of carriers.
Ion beam mixing of Pt/GaAs and formation of ohmic contacts
Authors: Tsutsui Kazuo , Furukawa Seijiro
Published: February 2003

Alloying was observed in the Pt/GaAs system, induced by ion beam mixing using Si+, Ar+, and Ge+ beams at room temperature. A 2.3-MeV He+ backscattering measurement showed that an alloyed layer was formed at the Pt/GaAs interface when these ions were implanted through Pt into GaAs, and that the thickness of the layer was proportional to the mass of the incident ion for a constant dose. Ohmic contacts were realized utilizing Si+ ion beam mixing in the Pt/GaAs system.
ac field effect in amorphous silicon
Authors: Srivastava A. K. , Narasimhan K. L. , Bapat D. R.
Published: February 2003

We have measured the frequency dependence of the field effect in amorphous silicon. We show that the frequency dependence allows us to separate out the effects of mobile charges and slow states in a field effect measurement. For a-Si on 7059 substrates, the value deduced from ac field effect for g(EF) differs only by a factor of two from that deduced from dc field effect measurements. We show from a study of the Nb2O5/a-Si interface that the ac field effect is not as sensitive to the nature of the interface as the dc field effect.
Influence of F and Cl on the recrystallization of ion-implanted amorphous Si
Authors: Suni I. , Shreter U. , Nicolet M-A. , Baker J. E.
Published: February 2003

The effect of fluorine and chlorine implantation on the solid-phase epitaxial regrowth of amorphized 〈100〉 Si was studied in intrinsic and heavily boron doped material. Annealings were performed at 500 and 600 °C. Both F and Cl retard the regrowth rate at 500 °C. The growth rates are much faster in B-doped than in undoped Si. Complete regrowth in B-doped Si is obtained for all investigated doses of fluorine up to 5×1015 F/cm2 at 600 °C for 30 min. The highest dose of chlorine (5×1015 Cl/cm2) stops the regrowth at this temperature.
Clausius equation and thermodynamics of a bistable liquid-crystal cell
Authors: Heffner William
Published: February 2003

The Clausius–Clapeyron equation has been extended to describe the temperature dependence of the operating voltage of a bistable liquid crystal cell. The voltage dependence is obtained in terms of the free energy derivatives of the two states of the bistable cell. These free energy derivatives may be calculated numerically. Furthermore, by employing a constant configuration approximation, these free energy derivatives yield a simple expression for the operating voltage as proportional to the square root of the ratio of the splay elastic constant to the dielectric anisotropy. This result provides a criterion for evaluating the temperature dependence of operation of various liquid crystal mixtures from the temperature dependence of elastic and dielectric constant data.
Compressibilities and high-pressure phase transitions of sodium tungstate perovskites (NaxWO3)
Authors: Hazen R. M. , Finger L. W.
Published: February 2003

Unit-cell parameters of the sodium tungstate perovskites, NaxWO3(x=0.55, 0.62, and 0.70), have been determined at a number of pressures to 5.3 GPa with single-crystal x-ray diffraction techniques. Pseudocubic Na0.55WO3 and Na0.62WO3 (probably tetragonal, C4/mmb, c>a at room pressure) have compressibilities of 0.0095(1) and 0.0084(1) GPa−1, respectively. The Na0.55WO3 perovskite compresses uniformly with pressure to 4.2 GPa, but Na0.62WO3 transforms reversibly at 1.8(1) GPa to a second single phase (presumably tetragonal, I4/mmm) with c<a and compressibility 0.0094(3) GPa−1. A volume change of −0.1% accompanies this reversible, first-order transition. Crystals of Na0.70WO3 (probably tetragonal, I4/mmm, c<a) have a room-pressure compressibility of 0.0110 (3) GPa−1; however, the compressibility of this phase decreases to less than 0.0070 GPa−1 at pressures above 2.5 GPa.
Precise determination of lattice parameter and thermal expansion coefficient of silicon between 300 and 1500 K
Authors: Okada Yasumasa , Tokumaru Yozo
Published: February 2003

The lattice parameter of high-purity silicon is measured as a function of temperature between 300 and 1500 K, and the linear thermal expansion coefficient is accurately determined. Precise measurements are made by the high-temperature attachment for Bond’s x-ray method to a few parts per million. It is found that the temperature dependence of the linear thermal expansion coefficient α(t) is empirically given by α(t)=(3.725{1−exp[−5.88×10−3{(t−124)} +5.548×10−4t)×10−6 (K−1), where t is the absolute temperature ranging from 120 to 1500 K. It is shown that the lattice parameter in the above temperature range can be calculated using α(t) and the lattice parameter at 273.2 K (0.5430741 nm). Measured values of the lattice parameter and the thermal expansion coefficient for high-purity float-zoned (100 kΩ cm) and Czochralski-grown (30 Ω cm) single crystals are uniformly distributed within ±1×10−5 nm and ±2×10−7 K−1 with respect to the values obtained from the above empirical formula.
Copper electromigration in polycrystalline copper sulfide
Authors: Allen Leslie H. , Buhks Ephraim
Published: February 2003

Measurements of the electrochemical potential distribution on polycrystalline Cu2-αS have been made. It was found that the basic transport mechanism for ionic conduction at temperatures between 25–70 °C for single phase chalcocite can be modeled as a vacancy mechanism. The chemical diffusion coefficient of copper in coper sulfide depends on the stoichiometry of the material and exhibit Arrhenius-type activated temperature dependence with the activation energy Ea=0.45 eV.
Flat-band voltage and surface states in amorphous silicon-based alloy field-effect transistors
Authors: Shur M. S. , Hack M. , Hyun C.
Published: February 2003

We propose a new technique to determine both the flat-band voltage and the characteristic energy of the deep localized states in amorphous silicon-based alloy field-effect transistors from their current-voltage characteristics. We also analyze the effects of surface states and show that they become important when their density is greater than 1011 cm−2 eV−1.
The interface and the field effect in thin-film transistors
Authors: Chen Inan
Published: February 2003

The effects of interface properties on the performance of thin-film transistors are examined theoretically. The static characteristics, e.g., the off conductance and the on-off ratio, and the dynamic response represented by the fraction of induced charge that is free, are considered. The interfaces, both at the gate side and the substrate side, are specified by the interface charge transfer (at equilibrium) from the semiconductor to the insulator, as well as the more familiar density of interface states. The properties of the two interfaces are found to control different regimes (high field and low field) of field-effect conductance. Thus, by a careful tailoring of the two interfaces, and/or the two insulator materials, the transistor characteristics can be optimized.
Some characteristics of In-diffused CuInSe2 homojunctions
Authors: Shih I. , Shahidi A. Vahid , Champness C. H.
Published: February 2003

CuInSe2 homojunctions have been fabricated by diffusing indium (at 200 °C) into p-type monocrystalline samples. The electrical and photovoltaic properties of the junctions were investigated at room temperature. The majority carrier concentration distribution in the p-type side of the junction was determined from differential capacitance measurements.
Optical bistability in nonlinear media: An exact method of calculation
Authors: Band Y. B.
Published: February 2003

The method of invariant imbedding is used to obtain exact equations for reflection and transmission coefficients for a plane wave incident on a slab of nonlinear material. These equations are solved for thin slabs of InSb and clear bistability is obtained.
High-energy (λ≲7300 Å) 300 K operation of single- and multiple-stripe quantum-well heterostructure laser diodes in an external grating cavity
Authors: Epler J. E. , Holonyak N. , Brown J. M. , Burnham R. D. , Streifer W. , Paoli T. L.
Published: February 2003

A set of high performance single- and multiple-stripe Alx′Ga1−x′As -AlxGa1−xAs quantum-well heterostructure (QWH) laser diodes coupled to an external grating cavity is used to demonstrate the tuning properties of a semiconductor laser at short wavelength (λ≲7300 Å). A single-stripe laser diode (6-μm stripe width) with a single AlxGa1−xAs (x∼0.22) quantum well of size Lz≊400 Å is broadly tunable (7080≤λ≤7370 Å, Δℏω∼70 meV) and delivers a single dominant longitudinal mode of moderate output power (Pout∼50 mW at 200 mA, pulsed). In continuous (cw) operation (I=135 mA) a single-stripe laser has a 36-meV tuning range, 7168≤λ≤7322 Å. Phase-locked twenty- and forty-stripe diodes (3.5-μm stripe width) from the same QWH wafer are capable of single-longitudinal-mode output at higher power (peak Pout∼1.6 W at a 8.0-A, 200-ns pulse) although at slightly longer wavelength and reduced tuning range (7225≤λ≤7425 Å). Data are presented illustrating the wavelength dependence of the gain and power output as well as the partial homogeneous broadening and phase-locked nature of the QWH laser arrays. The difference in performance of the multiple-stripe diodes compared with the single-stripe structure can be attributed to the internal coupling of the optical field in neighboring stripes and the reduced threshold current density.
An experimental method for the determination of rare gas halide laser medium parameters
Authors: Feiock F. D. , Oldenettel J. R. , Miscikowski G. R.
Published: February 2003

An experimental method based on the measurement of laser energy output from three flat-flat resonators with different outcoupling fractions is used to determine the gain medium parameters for an electron-beam pumped XeF laser. The sensitivity of the procedure to experimental errors is discussed. The resulting gain parameters are used to predict the laser output from an unstable resonator on the same laser and the results compared with experimental values.
Analysis of temperature sensitive operation in 1.6-μm In0.53Ga0.47As lasers
Authors: Takeshima Masumi
Published: February 2003

Temperature sensitive operations in 1.6-μm In0.53Ga0.47As lasers are analyzed assuming an extrinsic optical loss due to impurities. As the intrinsic loss mechanism, the intervalence-band absorption is considered for photons and the Auger recombination for excited carriers. The hot carrier effect is taken into account in terms of the hole population in the spin splitoff band. Experimental data can be well explained in terms of the extrinsic optical loss, which is most likely to occur in the cladding region outside the active region, with an activation energy of 0.19–0.28 eV.
Small and sensitive systems interacting with millimeter and submillimeter waves: Rydberg atoms in a cavity
Authors: Goy P. , Raimond J. M. , Haroche S. , Gross M.
Published: February 2003

A small number N (105≥N≥1) of sodium atoms in an atomic beam are prepared by pulsed laser excitation in a nS Rydberg level (n≂30) while transversing a millimeter wave Fabry–Perot cavity tuned to a transition connecting the nS state to a nearby n′P level. The atoms absorb the radiation in the cavity (nS→nP upward transition), or amplify it in a maser process [nS→(n−1)P, nS→(n−2)P... downward transition]. Due to the huge size of the electric dipole matrix element between nearby Rydberg levels, the system is extremely sensitive to the millimeter wave radiation field (enhanced by the tuned cavity) in both absorption and emission processes. Simple numerical expressions are given. The experiments demonstrate that the system can be used as an absolute power meter, an ultrasensitive millimeter photon counter, an absolute quantum thermometer, and a transient millimeter-wave amplifier.
Energy spectra of electrons backscattered from thick layers of C, Al, Cu, and Pb bombarded with 15.0- and 24.8-MeV electrons
Authors: Mikado Tomohisa , Tomimasu Takio , Yamazaki Tetsuo
Published: February 2003

Energy spectra of backscattered electrons from thick layers of C, Al, Cu, and Pb bombarded with 15.0- and 24.8-MeV electrons were measured at 120°. The variation of the observed energy spectra with initial electron energy is shown graphically by plotting the data against E/E0, where E0 and E are energies of initial and backscattered electrons, respectively. Frank’s prediction concerning energy distribution of backscattered electrons is supported by two energy spectra observed in the present work. The atomic-number dependence of relative values of differential number- and energy-backscattering coefficients and average energy of backscattered electrons is shown. All of them become larger as Z increases as supporting a simple insight that predicts that a high-Z material can reflect more electrons than a low-Z material.
Convergent Fourier–Bessel series to calculate potential and field strength in rotationally symmetric lens systems
Authors: Simons J. , Heerens W. Chr.
Published: February 2003

In this article a complete calculation strategy is given for potential and field strength in rotationally symmetric lens systems. The equations for these quantities are based on Fourier–Bessel series solutions. The series coefficients can be given analytically when simple boundary conditions are assumed, such as a rectangular cross section of the system and linear and logarithmic interpolation of the potentials on the walls between the points where this potential is given. It can be shown that with a continuous potential overlay on the walls the potential equations can be differentiated term by term and will also give convergent series. Methods to accelerate convergence of the calculations of the series are briefly discussed. Finally, some details are given on the calculation strategy of realistic lens systems, consisting of more than one rectangular element. The potential distributions on gaps or diaphragms, forming parts of the rectangular boundaries of one such element, are not exactly known in this case. It can be shown however that such potentials can be easily calculated with known finite-difference techniques on the basis of the equations given.
Cavity length detuning properties in synchronous mode locking
Authors: Urisu Tsuneo , Mizushima Yoshihiko
Published: February 2003

Cavity length detuning characteristics on pulse width and spectrum bandwidth, considering intracavity bandwidth limiting elements and absorber dye addition effects, have been measured in a synchronous mode-locking Oxazine 725 dye laser system. Experimental results are in good agreement with a simplified cavity length detuning equation.
Electron leakage in 1.5-μm InGaAsP separate confinement heterostructure lasers
Authors: Westbrook L. D. , Nelson A. W.
Published: February 2003

The extent of electron leakage in λ=1.55 μm InGaAsP separate confinement heterostructure (SCH) lasers, and its dependence on the p-buffer layer crystal composition, have been studied both experimentally and theoretically. A significant difference was observed between the light output characteristics of 1.55-μm SCH lasers with λ≡1.3 buffer layers fabricated by a one-stage liquid phase epitaxy growth process and those produced by a two-step technique, suitable for the fabrication of distributed feedback lasers, comprising liquid phase epitaxy and metalorganic chemical vapor deposition. These observations are attributed to the poor electron confinement in SCH lasers with λ≡1.3 μm buffer layers which is compounded by the introduction of nonradiative interfacial recombination centers by the interruption of the growth procedure. Bulk recombination in the p-buffer layer is shown to be a problem for buffer layer compositions of lower band gaps and a composition of λ≡1.2 μm is determined to be a good compromise between electron confinement and optical wave interaction.
Quenching of metastable states of rare gases by copper atoms
Authors: Rawnitzki G. , Rosenwaks S.
Published: February 2003

The rate constants for quenching of metastable He, Ne, Ak, Kr, and Xe by copper atoms have been measured at room temperature and found to be (0.93, <0.2, 1.4, 2.3, and 2.6×10−10 cm3 s−1, respectively. The rate constants have been measured indirectly, applying an internal calibration method in whch the copper atoms are used as both quenchers and tracers. The quenching cross sections of the metastable rare gases are related to their polarizabilities. It is suggested that the relatively small quenching rate of metastable Ne by Cu might influence the electron temperature of the gas mixture and therefore contributes to the successful use of neon as a buffer gas in the copper-vapor laser.
Channelled-substrate buried heterostructure InGaAsP/InP lasers with vapor phase epitaxial base structure and liquid phase epitaxial regrowth
Authors: Wilt D. P. , Karlicek R. F. , Strege K. E. , Dautremont-Smith W. C. , Dutta N. K. , Flynn E. J. , Johnston W. D. , Nelson R. J.
Published: February 2003

Channelled-substrate buried heterostructure InGaAsP/InP lasers have been fabricated with vapor phase epitaxial grown base structures and liquid phase epitaxial regrowth. These devices have low pulsed threshold currents (14 mA minimum, median 19 mA), exhibit a pulsed threshold current temperature dependence with a characteristic temperature of 55 K, and operate cw up to 80 °C heat sink temperature. Life test results on these lasers have exhibited degradation rates in range 0–3 mA per thousand hours on burned-in laser under 60 °C and 3 mW automatic power control accelerated aging conditions.
Ultrasonic method for shear strength prediction of spot welds
Authors: Rokhlin S. I. , Adler Laszlo
Published: February 2003

A novel ultrasonic method was developed to evaluate shear strength of a spot weld. This method is based on an analytical expression relating the transmission coefficient of Lamb waves passing through an aperture in solid plates to the aperture size. Simultaneously, a fracture mechanics model was introduced to correlate fracture load to the dimension of a spot weld. Consequently, the ultrasonic Lamb wave transmission coefficient was measured through spot welds and related to fracture load. There is good agreement between experimental results and model predictions. It appears that ultrasonic waves can be used to estimate shear strengths of spot welds.
Criteria for the ultrasonic measurement of thicknesses by interferometric methods
Authors: Houze M. , Nongaillard B. , Rouvaen J. M. , Lefebvre J. E. , Gazalet M. G.
Published: February 2003

An ultrasonic interferometer, aimed at the measurement of coating thicknesses and working in a pulsed mode, has been described recently. A new scheme for using this apparatus is proposed here, which applied to the case where a severe acoustic impedance mismatch exists between the measured slice and the surrounding media. Optimal operating conditions for the new scheme and the older one are theoretically discussed and experimentally checked. Owing to the actual impedance mismatch, a choice criterion between the two schemes is then derived.
Effects of transpiration on free convection of air along a nonuniformly heated vertical plate
Authors: Chuang H. , Sanchez H.
Published: February 2003

Similar solutions for free convection of air along a nonuniformly heated vertical plate with transpiration are shown to exist for various thermal shape factors and transpiration parameters. Velocity and temperature profiles were calculated. Skin friction at the wall increases with decreasing thermal shape factor and varies irregularly with transpiration. Heat transfer at the wall increases with both transpiration and the thermal shape factor. For flows of air along a nonuniformly heated vertical plate with negative thermal shape factor and with or without transpiration, the temperature gradient at the wall changes sign from negative to positive. This result actually implies that the wall is heated by some upstream fluid which is convected into this region.
Theory of electron multiplication in gases in strong weakly nonuniform electric fields
Authors: Friedland L. , Kagan Yu. M.
Published: February 2003

A theory of avalanche ionization of gases in weakly nonuniform electric fields is developed. The generally nonlocal problem of the current growth is reduced to the solution of two ordinary differential equations. As an example the theory is applied to the case of the discharge between two concentric cylindrical electrodes.
Retrograde motion of a positive column of low pressure discharge
Authors: Yamane Mikiya , Watanabe Yoshio
Published: February 2003

The motion of a positive column of low pressure discharge passing through the annulus between coaxial glass tubes and subjected to a transverse magnetic field has been investigated. The positive column was photographed and measured optically, and was found to move in the retrograde direction. Variation in this retrograde motion with tube geometry, discharge current and gas pressure was measured and examined based on the ‘‘neutral drag instability theory’’ of Hoh and Simon.
Theoretical modeling of the plasma erosion opening switch for inductive storage applications
Authors: Ottinger P. F. , Goldstein S. A. , Meger R. A.
Published: February 2003

A theoretical model for the plasma erosion opening switch (PEOS) is presented which predicts its voltage, current and impedance history as a function of the input waveforms, geometry, and switch parameters. Scaling relations for the switch operation are developed from this model. System requirements for pulse compression and power multiplication using inductive storage are derived from a simple lumped circuit analysis and a transmission line analysis. These requirements are shown to be satisfied using the PEOS as a fast opening, vacuum switch in a configuration relevant for existing high-power accelerators. The switch model is incorporated into a transmission line code for comparison with recent inductive storage experiments. Code results agree well with the data showing conduction times of ∼60 ns and switching times of ∼10 ns with peak currents of ∼600 kA.
Glow-discharge-created electron beams: Cathode materials, electron gun designs, and technological applications
Authors: Rocca J. J. , Meyer J. D. , Farrell M. R. , Collins G. J.
Published: February 2003

The operating characteristics of glow-discharge-created electron beams are discussed. Ten different cathode materials are compared with regard to maximum electron beam current achieved and the beam generation efficiency as measured calorimetrically. Specific electron gun designs are presented for a variety of applications that include: cw ion laser excitation; electron beam assisted chemical vapor deposition of microelectronic films; and wide area annealing of ion-implantation damage to silicon substrates. The use of sintered metal-ceramic (e.g., Mo-Al2O3) cathodes to generate multikilowatt electron beams in a pure noble gas discharge is reported. Cathode materials with high secondary electron emission coefficients by ion bombardment allow for electron beam production in glow discharges at 50%–80% generation efficiency values.
Metastable helium density in gas discharges in He-H2O mixtures
Authors: Sheldon J. W. , Anderson E. D. , Hardy K. A.
Published: February 2003

A theoretical description of the positive column is presented which balances metastable loss rates due to radial diffusion and water vapor quenching with production by electron bombardment excitation. The predicted relative dependence of metastable atom density on discharge current and pressure similarity parameters is in agreement with present experiments and a previous more detailed theory.
Electrode noise in beta aluminas
Authors: Brophy James J. , Smith Steven W.
Published: February 2003

Experimental contact noise spectra of Na β″ alumina and Ag β″ alumina ceramics at room temperature exceed low-frequency thermal noise for both blocking and ohmic electrodes. Contact noise spectra above 102 Hz for ohmic electrodes of sodium amalgam and NaI in propylene carbonate agree with Nyquist noise levels determined from ac impedance measurements, and the low-frequency excess noise is shown to be associated with nonequilibrium electrochemical processes. Similar effects are found for ohmic silver amalgam and aqueous AgNO3 electrodes on Ag β″ alumina. Greatly increased voltage fluctuations are observed to accompany current in the sample, and both contact current noise and bulk granular current noise have similar characteristics. A total dc charge flow fo 25 C/cm2 at sodium amalgam electrodes to Na β″ alumina increases both contact and current noise many orders of magnitude and can be returned to initial levels by equivalent reverse charge flow. No corresponding changes in conventional experimental measurements, e.g., current-voltage characteristics, are detected.
Critical current and upper critical field of multifilament Nb3−xTaxSn superconductor
Authors: Schwall R. E. , Ozeryansky G. M. , Foner S. , McNiff E. J.
Published: February 2003

Superconductive wires containing 78 filaments of Nb3−xTaxSn for 4–16 at. % Ta were produced using the external bronze process to yield a composite with an overall composition 21.4 wt. % Nb–Ta, 64.9 wt. % Cu, and 13.6 wt. % Sn. Reaction periods of 20 to 260 h at temperatures from 650 to 735 °C were used. Critical-current densities over the entire wire cross section were 5×104 A/cm2 at 14 T and 1×104 at 19.7 T, the measured Hc2 was 27 T at 4.2 K for wires with 8 μm filaments containing approximately 4 at. % Ta. Single filament wires using a 13 wt. % bronze matrix were fabricated to determine the effect of Ta on reaction kinetics. The A15 layer thickness was approximately proportional to the square root of the reaction time and independent of tantalum concentration. The critical-current densities are discussed in terms of A15 grain structure, stoichiometry, filament uniformity, and Hc2 enhancement.
Resistance of Nb-Pb-alloy Josephson tunnel junctions at cryogenic and ambient temperatures
Authors: Beattie R. W. , Donaldson G. B. , Moore D. F.
Published: February 2003

We report experimental measurements of the ratio of the tunneling resistance of edge junctions at ∼4 and ∼300 K. The results, after correction for the contribution of the electrode resistance in the normal state, are compared with theory. The temperature dependence measured in these Nb–NbOx–Pb-alloy junctions is greater than the theory for a simple trapezoidal ∼0.5 eV high barrier. Nevertheless, the consistency of the ∼4 and ∼300 K tunneling resistances is adequate to allow the use of the resistance at ambient temperature as a process monitor in Josephson junction circuit fabrication.