bluuebunny/crossref_metadata_2025 huggingface dataset:
Semiconductor interferometric laser
Authors: Fattah Ismail H. A. , Wang Shyh
Published: February 2003

A novel semiconductor laser employing a cavity structure of the open ended Michelson interferometer is studied. The interference effect is used to select and stabilize the longitudinal mode of the laser. Experimental results showed that lasing action is observed only at the few coincident resonant modes that do not suffer any interference loss. Hence the operating wavelength is primarily determined by the cavity dimensions. The laser showed a change of 0.667 Å/ °C in its lasing wavelength with temperature, a considerable improvement over the conventional Fabry–Perot lasers.
A GaAsxP1−x/GaP strained-layer superlattice
Authors: Osbourn G. C. , Biefeld R. M. , Gourley P. L.
Published: February 2003

Strained−layer superlattices form a broad new class of semiconductor materials with tailorable electronic properties. We have succeeded in growing a GaAsxP1−x/GaP(100) strained−layer superlattice (SLS). The structure was grown by alternate metalorganic chemical vapor deposition of thin (60 Å)layers (20 each) of GaAs0.4P0.6 and GaP. These layers were grown onto a GaAsxP1−x layer which was graded in composition from x = 0 (composition of underlying GaP substrate)to x = 0 (average composition of the SLS). Photoluminescense studies of the SLS were carried out to determine the optical band gap. At T = 78 K, the spectrum shows a dominant band−edge peak at 2.03 eV as well as weaker peaks at higher energies. Tight binding and effective mass calculations, also carried out, predict a direct band gap (due to zone folding) of 2.02 eV and higher lying transition energies which are in good agreement with these data.
Mobility of copper centers in reverse-biased germanium junction diodes
Authors: Pearton S. J. , Tavendale A. J.
Published: February 2003

The motion of copper centers in reverse-biased germanium n+-p junctions has been observed using deep level transient spectroscopy. The concentration profile of the doubly ionized copper center is presented as a function of the duration of the electric field application. A mobility of 9.0±4.8×10−12 cm2/Vs at 25 °C was obtained for the Cu2− center.
Photothermal ionization identification of sulfur donors in GaAs
Authors: Low T. S. , Stillman G. E. , Nakanisi T. , Udagawa T. , Wolfe C. M.
Published: February 2003

Photothermal ionization data for undoped and S-doped epitaxial GaAs grown by metalorganic chemical vapor deposition (MOCVD) are presented which permit the positive identification of the S donor. This identification is unambiguous because S is not a significant residual impurity in the undoped MOCVD GaAs used for these measurements. Implications of the new identification for the importance of S as a residual donor in epitaxial GaAs prepared by various other growth techniques.
InP/InGaAs heterojunction phototransistor with integrated light emitting diode
Authors: Campbell J. C. , Dentai A. G.
Published: February 2003

We describe a novel heterojunction phototransistor structure which incorporates an integrated light emitting diode (LED) to provide an optically coupled dc bias current. A drive current of 6 mA through the LED results in a threefold decrease in the rise time (from 210 to 70 ns) and a twofold increase in the gain (from 30 to 60). The optically coupled dc bias can be adjusted to optimize the bandwidth and signal to noise ratio for particular applications.
Bias-free selectively doped AlxGa1−x As-GaAs picosecond photodetectors
Authors: Chen C. Y. , Cho A. Y. , Bethea C. G. , Garbinski P. A.
Published: February 2003

We demonstrate a novel AlxGa1−x As-GaAs picosecond photodetector which does not require any bias voltage. High-speed operation is achieved by an inherent capacitive coupling, a unique microwave mounting scheme, and a selectively doped structure. An observed rise time of 30 ps and a full width at half-maximum of 60 ps have been reproducibly obtained for a device with an area two orders of magnitude larger than a previously reported device. This detector enables monolithic integration with modulation-doped field-effect transistors. Furthermore, the results point to a possibility of achieving a bias-free detector for a gigabit-rate optical communication system.
Melting model and Raman scattering during pulsed laser annealing of ion-implanted silicon
Authors: Wood R. F. , Lowndes D. H. , Jellison G. E. , Modine F. A.
Published: February 2003

Compaan and coworkers have reported the results of Raman scattering experiments on ion- implanted Si which they claim disprove the melting model of pulsed laser annealing. These results concern the onset of a Raman signal after an intense laser pulse, the simultaneous occurrence of a Raman signal and a high reflectivity phase characteristic of molten Si, and the lattice temperature measured by Raman scattering. It is shown here that there is, in fact, good agreement between the experimental results and the predictions of the melting model.
Superconductor-insulator-superconductor reflection parametric amplifier
Authors: Lee G. S.
Published: February 2003

An analysis of reflection parametric amplifiers using superconductor-insulator-superconductor (SIS) junctions is presented. Both singly degenerate (three-photon) and doubly degenerate (four- photon) schemes are possible. Due to the fact that the reactive part of the quasiparticle response function Re j1 rises steeply just below the gap frequency, whereas the resistive part Im j1 remains 0 until the gap, the SIS junction may be operated as a purely reactive device. The quantum limit for detectable power h/ω B is therefore achievable.
Submicrometer-linewidth doping and relief definition in silicon by laser- controlled diffusion
Authors: Ehrlich D. J. , Tsao J. Y.
Published: February 2003

Boron doping patterns characterized by very sharp lateral edge definition and 300–1000-nm linewidths have been written in silicon by localized heating with a diffraction-limited cw laser beam. The tightly focused beam generates free dopant atoms, and simultaneously promotes solid- state diffusion into the substrate. The nonlinear dependence of diffusion rates on temperature results in linewidths substantially narrower than both the temperature and the laser beam profiles on the surface. An enhancement is observed in diffusion rates under the strong thermal gradients created.
Low threshold, high efficiency Ga1−xAlxAs single quantum well visible diode lasers grown by metalorganic chemical vapor deposition
Authors: Burnham R. D. , Scifres D. R. , Streifer W.
Published: February 2003

Laser threshold current density and emission wavelength were investigated for broad area single quantum well double heterostructure (SQW DH) Ga1−xAlxAs lasers grown by metalorganic chemical vapor deposition (MOCVD) under pulsed operation at room temperature. The shortest lasing emission wavelength was 7065 Å. At that wavelength, the threshold current density was 1 kA/cm2 for a Fabry–Perot diode of 500-μm cavity length and the external differential quantum efficiency was 48%. These values are significantly better than those previously reported for Ga1−xAlxAs DH lasers operating under similar conditions at the same wavelengths. We attribute the improved performance in part to the quantum size effect (active layer thickness 400– 600 Å).
Highly resolved, monochromatic, x-ray images of laser-produced plasmas through the single-crystal double-reflection spectrometer
Authors: Fraenkel Benjamin S.
Published: February 2003

The double-reflection method is used to produce highly collimated x-ray spectra, down to less than 0.1 mrad, from laser-produced plasmas. Thus images of the plasmas are obtained for each wavelength. He-like and Li-like transitions from sulfur and titanium are shown. The first results give the different sizes of the volumes in the plasmas emitting the various species of ions.
Atomic displacements in metals due to low-energy light ion implantation
Authors: Bernas H. , Traverse A.
Published: February 2003

Damage production rates due to 3–10-keV proton and deuteron implantations at 6 K into thin metallic (Ni, Pt, Pd, Ag, Au, Cr) films were deduced from residual resistivity measurements. A simple analytical calculation, taking into account the dominating contribution of electronic stopping and the low recoil energies involved, accounts for the experimental results. It is also directly applicable to low-energy T and 4He implantation results.
Preparation of x-ray lithography masks using a tungsten reactive ion etching process
Authors: Randall John N. , Wolfe J. C.
Published: February 2003

High-resolution x-ray lithography masks which use a tungsten absorbing layer were fabricated on polyimide support membranes. The tungsten was patterned with a reactive ion etching process. 70-nm lines and spaces have been replicated in polymethylmethacrylate (PMMA) using carbon K x rays. The process should allow high-resolution, high-contrast masks to be made for any wavelength.
X-center formation by neutron irradiation of Ga-doped float-zone silicon
Authors: Rome John J. , Mitchel W. C. , Brown Gail J. , Fischer David W. , Ohmer M. C. , Peterson T. L.
Published: February 2003

Neutron irradiation of gallium-doped float-zone grown silicon has been observed to cause the appearance of the gallium X center. Hall effect, infrared absorption, and photoconductivity (photothermal ionization) were used to reveal its presence. The X center was seen in irradiated samples but not in unirradiated ones under identical annealing conditions. The measured ionization energy of this center agrees well with previously reported data (0.057 eV).
Measurement of lateral variation of hole diffusion lengths in GaAs
Authors: Fletcher Robert M. , Wagner D. Ken , Ballantyne Joseph M.
Published: February 2003

A technique for making rapidly scanned, high spatial resolution minority-carrier diffusion length measurements in direct band-gap semiconductor thin films is described. Using optical excitation of carriers through a semitransparent Schottky barrier, the technique is nondestructive, and at the highest resolution of 1 μm, permits measurements over a 100-μm square area to be made in a matter of minutes. The technique is applied to the investigation of grain boundaries in large- grained polycrystalline n-type GaAs films and is illustrated by measurements over a region containing an electrically active grain boundary. Application of the method for assessment of uniformity of minority-carrier properties of epitaxial layers is feasible.
Transport in modulation-doped structures (AlxGa1−xAs/GaAs) and correlations with Monte Carlo calculations (GaAs)
Authors: Drummond T. J. , Kopp W. , Morkoç H. , Keever M.
Published: February 2003

Electron velocity and mobility versus electric field measurements were made in AlxGa1−xAs/GaAs modulation-doped structures in an electric field range of 0–2 kV/cm and in a temperature range of 77–300 K. The electron velocities obtained at 2 kV/cm were 1.7×107 cm/ s at 300 K and 2.24×107 cm/s at 77 K. The velocity-field and mobility-field characteristics obtained were in very good agreement with Monte Carlo results for undoped GaAs, suggesting that existing Monte Carlo calculations are capable of predicting transport in AlxGa1−xAs/GaAs modulation-doped structures. An ideal modulation-doped structure can thus be assumed to exhibit transport properties identical to that of undoped GaAs. The advantage of modulation doping is the ability to place 7×1011 cm−2 electrons at the heterointerface for current conduction for devices, while avoiding all the adverse effects of impurity scattering.
Natural lithography
Authors: Deckman H. W. , Dunsmuir J. H.
Published: February 2003

A new form of microfabrication is presented in which spherical colloidal particles are used to define a large area lithographic mask. A monolayer of colloidal particles is deposited in either random or ordered array over the entire surface of a macroscopic substrate. Large area random or ordered mosaic arrays of identical submicron microcolumnar structures are produced by using the colloidal particles as either an etching or deposition mask.
Steady state model of an illuminated liquid-junction solar cell
Authors: Pinson Wm. E.
Published: February 2003

We propose that the position of the semiconductor band edges relative to the electrolyte redox potential at an illuminated semiconductor-electrolyte interface is determined by the minority photocurrent at the interface and its interaction with the density of states distribution of the redox couple, rather than by a flatband potential or by Fermi level pinning. The model is demonstrated for a solar illuminated Au/n-GaAs0.6P0.4 photoanode in contact with electrolytes having redox potentials differing by 0.8 V.
Measurement of spontaneous emission efficiency and nonradiative recombinations in 1.58-μm wavelength GaInAsP/InP crystals
Authors: Asada Masahiro , Suematsu Yasuharu
Published: February 2003

Nonradiative recombination in 1.58-μm wavelength GaInAsP/InP crystals is discussed with the measured results of the light output saturation and the carrier lifetime of light emitting diodes. Measured results of the spontaneous emission efficiency depend strongly on temperature, and nonradiative recombination is dominant in the carrier lifetime at room temperature. The reciprocal of nonradiative recombination time 1/τNR is expanded into the power series of the carrier density n as Ā+B̄NRn+C̄n2, where the three terms express the nonradiative centers, the carrier overflow, and the Auger recombination, respectively. It is shown that the coefficient C̄ is almost constant for temperature while B̄NR increases rapidly with increasing temperature, and Ā is negligible. The proportions of the carrier overflow and Auger recombination in the above approximation of 1/τNR are 71 and 29%, respectively, at room temperature at the carrier density of 1×1018 cm−3.
Measurement of third order nonlinear susceptibilities by surface plasmons
Authors: Chen Y. J. , Carter G. M.
Published: February 2003

We have developed a novel technique which utilizes the intensity-dependent dispersion relation of surface plasmons to study the third order nonlinear susceptibility coefficient χ(3). This new technique yields information about both the magnitude and the sign (with respect to χ(1)) of χ(3). Experimental results are reported for GaAs and Si at input wavelengths of 1.05 and 1.11 μm, respectively.
Direct detection of vacuum ultraviolet scintillations in liquid helium using germanium photodiodes
Authors: Luke Paul N. , Steiner Herbert M. , Haller E. E.
Published: February 2003

Direct detection of vacuum ultraviolet scintillations in liquid helium produced by 5.3 MeV α particles has been accomplished using a high-purity germanium photodiode. The diode was immersed in the liquid helium and operated in the side-entry mode with a senstive area of 0.3×1.0 cm. Scintillation from each α particle was detected as a single pulse. A signal rise time <0.1 μs was obtained at an electric field ≳1200 V cm−1. The quantum efficiency of the photodiode was estimated to be ∼4.
High energy AlxGa1−xAs (0⩽x⩽0.1) quantum-well heterostructure laser operation
Authors: Camras M. D. , Holonyak N. , Hess K. , Coleman J. J. , Burnham R. D. , Scifres D. R.
Published: February 2003

Besides high pressure or bulk crystal composition change, a size-determined direct-indirect transition can be obtained in an AlxGa1−xAs (0⩽x⩽0.1) quantum-well heterostructure (QWH), in fact, at higher energy (E∼2.05 eV) than in bulk AlxGa1−xAs (∼1.98 eV). Laser operation is demonstrated at 6700–6500 Å on a QWH grown by metalorganic chemical vapor deposition (MOCVD).
New type of thin-film electroluminescent device having a multilayer structure
Authors: Suyama Takahiro , Okamoto Kenji , Hamakawa Yoshihiro
Published: February 2003

A new kind of multilayered thin-film electroluminescent (EL) device is proposed. The device consists of multiple alternate layers in which the functions of carrier acceleration and light emission are separated. One big advantage of the proposed structure is that the light emitting phosphor can be selected independently of the carrier accelerating material, thus permitting a variety of color emissions. Therefore, one can optimize the device performance by selecting combinations of materials and cell structure design parameters. For example, a device employing ZnS and Y2O3:Eu thin films as the carrier accelerator and light emitter, respectively, emits a red color, and a brightness level of 40-ft lambert has been obtained under sinusoidal voltage excitation of 5 kHz. This value is several times higher than that reported for EL in powdered layers of Y2O3:Eu.
Electron mobility enhancement in epitaxial multilayer Si-Si1−xGex alloy films on (100) Si
Authors: Manasevit H. M. , Gergis I. S. , Jones A. B.
Published: February 2003

Enhanced Hall-effect mobilities have been measured in epitaxial (100)-oriented multilayer n-type Si/Si1−xGex films grown on single-crystal Si substrates by chemical vapor deposition. Mobilities from ∼20 to 40% higher than that of epitaxial Si layers and ∼100% higher than that of epitaxial SiGe layers on Si were measured for the doping range ∼8×1015–∼1017 cm−3. The mobilities of multilayer Si/SiGe films approach that of single-crystal Si films at ∼2×1017 cm−3. No mobility enhancement was observed in multilayer p-type (100) films and n-type (111)-oriented films. Experimental studies included the effects upon film properties of layer composition, total film thickness, doping concentrations, layer thicknesses, and growth temperature.
Electron drift velocity measurement in compositionally graded AlxGa1−xAs by time-resolved optical picosecond reflectivity
Authors: Levine B. F. , Tsang W. T. , Bethea C. G. , Capasso F.
Published: February 2003

We have measured for the first time the velocity of minority-carrier electrons in a heavily doped (p = 2×1018 cm−3) molecular beam epitaxy grown compositionally graded (0.12 eV/μm) AlxGa1−x As layer. The drift velocity is determined to be ve = 2.3×106 cm/s in a quasi-electric field of 1.2 kV/cm.
Threshold and memory switching in polycrystalline silicon
Authors: Mahan John E.
Published: February 2003

Both threshold and memory switching have been observed in very high value resistors formed from undoped low pressure chemical vapor deposited (LPCVD) polycrystalline silicon and of a size suitable for microelectronic application. The resistors undergo a reversible, current-controlled negative resistance transition at a threshold voltage of around 50 V. A slightly higher applied voltage induces the memory switching transition, with a permanent increase in conductance of more than a factor of 106. It is suggested that threshold switching occurs via charge injection that neutralizes grain boundary potential barriers, thereby increasing the carrier mobility. It is probable that the memory switching event is due to the formation of a permanent, relatively conductive filament induced by Joule heating of the material.
Spatial light modulation using electroabsorption in a GaAs charge-coupled device
Authors: Kingston R. H. , Burke B. E. , Nichols K. B. , Leonberger F. J.
Published: February 2003

High-speed one- and two-dimensional spatial light modulation may be carried out using the electroabsorption (Franz-Keldysh) effect in a GaAs buried-channel charge-coupled device (CCD). For photon energies slightly lower than the energy gap, the transmission through or along the surface of a CCD structure may be controlled by the signal charge in the wells, through the change of electric field with charge. The modulator is thus electrically addressable and it promises optical quality sufficient for coherent applications. Experimental measurements on a specially designed GaAs CCD structure with semitransparent gates have verified the predicted performance.
Diffusion of fast electrons in the presence of a magnetic field
Authors: Tekula M. S. , Jacob J. H.
Published: February 2003

The Boltzman equation, for energy deposited by fast electrons in the presence of an applied magnetic field, is solved in the diffuse beam approximation. The solution is obtained by a simple coordinate transformation which is valid both when λ/rL⩽0.25 (λ = mean free path, rL = Larmor radius) and when λ/rL ⩾4.5. The half-space solution is used to determine the dose in a gas. The theoretical results are compared with experiments. It is found that agreement is better than *10% for cases of interest.
Percolation-type behavior in black chrome selective solar films
Authors: Zajac G. , Ignatiev A.
Published: February 2003

The optical constants (n and k) and dc resistivity have been measured for black chrome particulate solar absorbing coatings for the purpose of defining the applicability of various inhomogeneous medium theories in the description of the black chrome optical response. It has been shown that percolation-type behavior does exist in the films and hence of the various theories, only those exhibiting percolation at the 0.3 packing fraction value determined for the black chrome films are applicable. The two valid approaches are an effective medium theory first proposed by Bruggeman and a modified Maxwell Garnett theory which includes a particle shape distribution.
Low temperature gettering of Cu, Ag, and Au across a wafer of Si by Al
Authors: Thompson R. D. , Tu K. N.
Published: February 2003

A set of sandwich structures consisting of a noble metal film of Cu, Ag, or Au on one side of a Si wafer (200 μm thick) and an Al film on the other side was annealed at 540 °C for 100 h to study the gettering of these noble metals across the wafer by Al. Rutherford backscattering spectroscopy was used to analyze the amount of these metals in the Al. A very large quantity of Cu(∼1021 atom/cm3) in the Al film was detected after the annealing but neither Ag nor Au could be found in the Al. The solubility of Cu in Si at 540 °C has been calculated to be 1.7×1014 atom/cm3.
Pulsed x-ray annealing of ion-implanted silicon
Authors: Sigmon T. W. , Osias D. E. , Schneider R. L. , Gilman C. , Dahlbacka G.
Published: February 2003

Annealing of As ion-implant-amorphized 〈100〉 Si using a pulsed imploding plasma x-ray source is reported. The wafers were exposed to a single 50-ns pulse of x rays. For wafers annealed in the energy density range 0.3–0.4 J/cm2, Rutherford backscattering and channeling show recovery of the crystallinity of the damaged layer with incorporation of about 86% of the implanted As onto substitutional lattice positions. Movement toward the surface and flattening of the As profile, characteristic of melting, was observed. Transmission electron and optical microscopy and spreading resistance measurements verified low defect levels remaining and uniform surfaces and electrical activity.
Impurity redistribution in Bi-implanted Si after nanosecond and picosecond Nd laser pulse irradiation
Authors: Campisano S. U. , Baeri P. , Rimini E. , Malvezzi A. M. , Russo G.
Published: February 2003

The redistribution in Bi-implanted Si was measured after irradiation with 25-ps or 35-ns Nd laser pulses by channeling effect measurements in combination with MeV He+ backscattering. For both pulse durations some of the Bi accumulated at the surface and the amount of segregation depended on the substrate orientation. The impurity redistribution was similar after nanosecond or picosecond laser pulses thus indicating that the solidification velocities were comparable for the two cases.
Lateral epitaxial overgrowth of GaAs by organometallic chemical vapor deposition
Authors: Gale R. P. , McClelland R. W. , Fan John C. C. , Bozler C. O.
Published: February 2003

Lateral epitaxial overgrowth of GaAs by organometallic chemical vapor deposition has been demonstrated. Pyrolytic decomposition of trimethylgallium and arsine, without the use of HCl, was used to deposit GaAs on substrates prepared by coating (110) GaAs wafers with SiO2, then using photolithography to open narrow stripes in the oxide. Lateral overgrowth was seeded by epitaxial deposits formed on the GaAs surfaces exposed by the stripe openings. The extent of lateral overgrowth was investigated as a function of stripe orientation and growth temperature. Ratios of lateral to vertical growth rates greater than 5 have been obtained. The lateral growth is due to surface-kinetic control for the two-dimensional growth geometry studied. A continuous epitaxial GaAs layer 3 μm thick has been grown over a patterned mask on a GaAs substrate and then cleaved from the substrate.
Uniformity of quantum well heterostructure GaAlAs lasers grown by metalorganic chemical vapor deposition
Authors: Scifres D. R. , Burnham R. D. , Bernstein M. , Chung H. , Endicott F. , Mosby W. , Tramontana J. , Walker J. , Yingling R. D.
Published: February 2003

The threshold current density, laser wavelength, grown layer thickness, reverse breakdown voltage, and far-field radiation pattern as a function of position on the grown wafer are reported for broad area multiple quantum well GaAlAs heterostructure lasers grown by metalorganic chemical vapor deposition. It is found that the layer thickness varies across a 1.5-in. sample by as much as 20% at the outer edges of the water, leading to a lasing wavelength shift of as much as 150 Å owing to the quantum size effect. It is shown that this thickness variation has only a small effect on the threshold current density across the water such that the uniformity of threshold current density is comparable to that reported previously for molecular beam epitaxy-grown conventional double heterostructure lasers.
Use of a GaAs smoothing layer to improve the heterointerface of GaAs/AlxGa1−xAs field-effect transistors
Authors: Kopp W. , Su S. L. , Fischer R. , Lyons W. G. , Thorne R. E. , Drummond T. J. , Morkoç H. , Cho A. Y.
Published: February 2003

The effect of a GaAs smoothing layer on the performance of GaAs/AlxGa1−xAs field-effect transistors prepared by molecular beam epitaxy was investigated. The GaAs smoothing layer was inserted between the channel layer and the AlxGa1−xAs buffer layer in an attempt to reduce the dependence of interface quality on growth conditions. Current-voltage characteristics of field-effect transistors with 1-μm gate lengths were used to characterize the properties of the heterointerface. Without the GaAs smoothing layer, extremely sharp interfaces, as indicated by the electron velocity, were obtained when the structures were grown at 700 °C. However, the interface sharpness was very sensitive to growth conditions and in particular to the substrate temperature, decreasing from 50 Å at 700 °C to 70 Å at 640 °C and to 260 Å at 580 °C. Incorporation of a 200-Å-thick undoped GaAs smoothing layer at the heterointerface decreased this sensitivity to growth conditions. With the smoothing layer, interface sharpnesses of 150, 60, and 50 Å were obtained for substrate temperatures of 580, 630, and 700 °C, respectively.
Far-infrared electron spin resonance of ruby in very high magnetic fields
Authors: Kido G. , Miura N.
Published: February 2003

Electron spin resonance (ESR) of ruby was observed in the far-infrared range at 336.6- and 118.6-μm wavelengths under very high magnetic fields in the megagauss range. It was confirmed that the g factor is constant up to a megagauss. Thus the ESR of ruby proved to be a good means for calibrating the ultrahigh magnetic fields.
Cathodoluminescence evaluation of dark spot defects in InP/InGaAsP light-emitting diodes
Authors: Chin A. K. , Zipfel C. L. , Mahajan S. , Ermanis F. , DiGiuseppe M. A.
Published: February 2003

In this study, the formation of dark spot defects (DSD’s) in InP/InGaAsP light-emitting diodes (LED’s) is evaluated by cathodoluminescence imaging and energy dispersive x-ray spectroscopy (EDS). Defects resulting in DSD’s are shown to be located in either the p-InGaAsP contact layer, the p-InP confining layer, or the InGaAsP active layer. The presence of gold was not detected at the DSD’s using EDS. However, gold was found in the form of submicron-sized inclusions in the contact layer and confining layer of cylindrically lapped wafers using EDS. Our results strongly suggest that the migration of gold from the p contact during device processing and aging results in the formation of DSD’s in InP/InGaAsP LED’s.
Critical currents in the Chevrel-phase lead molybdenum sulfide thin films
Authors: Hamasaki K. , Inoue T. , Yamashita T. , Komata T. , Sasaki T.
Published: February 2003

Critical currents in thin films of Chevrel-phase lead molybdenum sulfide have been measured as a function of applied magnetic field up to 8.5 T. The magnetic field was perpendicular or parallel to the film plane, and a 5-μV/cm criterion was used to define the critical current density Jc. The maximum value of critical current density was above 106 A/cm2 at zero field and 5×104 A/cm2 at 8 T. These values are greater than the best reported so far.
Aging tests of low threshold current InGaAsP/InP V-grooved substrate buried heterostructure lasers emitting at 1.3-μm wavelength
Authors: Imai Hajime , Ishikawa Hiroshi , Hori Ken-ichi , Takahei Ken-ichiro
Published: February 2003

Aging tests of InGaAsP/InP V-grooved substrate buried heterostructure lasers have performed. The cw threshold current of these lasers is around 20 mA at 25 °C. The laser are tested at 10, 50, and 70 °C with a constant optical power of 5 mW/facet and are still operating at over 5000 h with only a slight increase in the driving current. The far-field pattern and lasing spectrum do not change appreciably during aging, and self-pulsation is not observed after aging.
Laser emission from stimulated spin-flip Raman scattering in (Cd,Mn)Se
Authors: Heiman D.
Published: February 2003

Stimulated spin-flip Raman scattering has been observed in the semimagnetic semiconductor Cd1−xMnxSe. g values as large as 170 were observed, allowing the spin-flip frequency to be tuned by 20 meV with magnetic fields below B = 30 kG. A threshold intensity of less than 1 MW/cm2 was found. This threshold varies rapidly with pump wavelength, and peaks near the donor-bound exciton energy. The tunability and gain coefficient are comparable to those in narrow-gap semiconductors, such as InSb and (Hg,Cd)Te, under nonresonant conditions. Laser action is achieved for longitudinal pumping.
High-power low-divergence superradiance diode
Authors: Wang C. S. , Cheng W. H. , Hwang C. J. , Burns W. K. , Moeller R. P.
Published: February 2003

Using a combination of antireflection coating and proton implantation techniques, GaAlAs double-heterostructure lasers are fabricated to operate in superradiant mode. Light output, in excess of seven milliwatts, is obtained with spectral half-power widths of 15–20 nm. This implies extremely short coherence lengths of less than 50 μm. Such a short coherence length light source should be very useful for many applications in fiber sensors and fiber optic communications. In particular, it has produced marked reduction (better than 15 dB) of coherent Rayleigh backscattering noise in a single-mode fiber. Since the laser operates in superradiant mode, the output light is only partially polarized, another unique characteristic that is important for fiber gyroscopes. The typical light output angle of 30°×50° also provides easy coupling into fibers. Coupling efficiencies of 80% into multimode fiber and over 20% into single-mode fiber have been achieved.
Frequency synchronization and phase locking of CO2 lasers
Authors: Leeb Walter R. , Philipp Heinz K. , Scholtz Arpad L. , Bonek Ernst
Published: February 2003

Employing the principle of a phase-locked loop (PLL) we have synchronized the frequency and phase of two CO2 lasers. The laser acting as voltage controlled oscillator is tuned both by electro-optic and piezoelectric means. A cooled photodiode serves as the phase detector. The main loop parameters, natural frequency ωn and damping factor ζ, have been measured. The small phase jitter in the error signal obtained will allow application of such an optical PLL in homodyne receivers at 10 μm.
Lateral beam collimation of a phased array semiconductor laser
Authors: Scifres D. , Burnham R. D. , Streifer W. , Bernstein M.
Published: February 2003

The lateral near-field and far-field radiation patterns of a phase-locked array of gain-guided semiconductor injection lasers are studied. These lasers exhibit a lateral far-field beam divergence full width at half-maximum (FWHM) of 1.5° up to 200 mW of output power per facet. Greater than 60% of the laser output power is concentrated in a low divergence beam at this high optical power. Catastrophic mirror degradation of the laser occurs at ≊250–270 mW cw per facet.
Spot-size dependence of laser-induced damage to diamond-turned Cu mirrors
Authors: Lee C. S. , Koumvakalis N. , Bass M.
Published: February 2003

A comparison of single and multiple pulse damage fluxes for oxygen-free high-conductivity (OFHC) diamond-turned Cu at 1.06 and 10.6 μm shows opposite trends in spot-size dependence. The single pulse damage threshold decreases or remains constant with increasing spot size in the range of sizes used (50–250 μm), but the multiple pulse threshold increases. However, both appear to have the same value in the limit of large spot size. These data suggest that the two phenomena are the result of different mechanisms. Models consistent with the data are discussed.
Profiling of deep impurities by persistent photocurrent measurements
Authors: Theodorou D. E. , Queisser H. J. , Bauser E.
Published: February 2003

A method to obtain the volume density Z of deep impurities in semiconductors versus their spatial depth is described. Z is derived by measuring the increase of the photoinduced persistent sheet density of carriers Δ(nd) in a conductive layer as a function of incident photon dose Q. The slope of the Δ(nd) =  f(log Q) curve depends upon the concentration profile of the deep traps in the substrate beneath the conductive layer, as is demonstrated by experiments using GaAs.
Optical input and output characteristics for bistable semiconductor lasers
Authors: Kawaguchi H.
Published: February 2003

Experimental results are presented regarding the switching of a bistable semiconductor laser’s output (PO) with injected optical power (PI). An incident optical beam, generated by an ordinary semiconductor laser, was injected into the bistable semiconductor laser with inhomogeneous excitation. The mutual relation between PI-PO characteristics and I-L characteristics for the bistable laser, and the dependence of PI-PO characteristics on the bias current of the bistable laser are described. Switching between the two stable bistable operation states is accomplished by injecting optical trigger pulses. Switching of the laser having differential gain characteristics, through use of optical pulse, is also looked at.
Characterization of damage in ion implanted Ge
Authors: Appleton B. R. , Holland O. W. , Narayan J. , Schow O. E. , Williams J. S. , Short K. T. , Lawson E.
Published: February 2003

It has been observed that ion implantation into Ge at room temperature creates severe surface craters extending several thousand angstroms into the surface, and results in the incorporation of large quantities of C and O impurities (∼50 impurities/ion). This effect has a strong temperature dependence and essentially disappears for implantations performed at liquid nitrogen temperature. The systematics of this effect are presented, preliminary annealing results are cited, and possible mechanisms are discussed.
Effects of dielectric relaxations and dual-frequency addressing on the electro-optics of guest-host liquid crystal displays
Authors: Schadt M.
Published: February 2003

Nematic as well as phase-change guest-host liquid crystal displays are shown to be dual-frequency addressable by using liquid crystalline hosts with suitable static and dynamic dielectric properties, thus rendering them multiplexable. Positive as well as negative optical contrasts and fast turn-off times can be achieved.
Interfacial properties of indium tin oxide/indium phosphide devices
Authors: Sheldon P. , Ahrenkiel R. K. , Hayes R. E. , Russell P. E.
Published: February 2003

Efficient indium tin oxide (ITO)/p-InP solar cells have been fabricated by ion beam deposition. In this letter, a critical evaluation of the ITO/InP interface is presented using complementary capacitance-voltage and ion microprobe measurements. We have found that deposition of ITO produces a semi-insulating region at the InP surface. This high resistivity layer extends about 750 Å into the bulk. We have evidence that this region is due to surface accumulation of compensating impurities.
Multiply scanned electron beam annealing of ion implanted indium phosphide
Authors: Gill Sukhdev S.
Published: February 2003

A multiply scanned electron beam has been used to anneal ion implanted indium phosphide in the dose range of 5×1012 to 3.6×1014 Se+/cm2. The power density was varied from 8 to 165 W/cm2, and exposure times were in the range 0.5–4.5 s. The best electrical activity for the dose of 5×1012 Se+/cm2 was 9% with a sheet mobility of 1400 cm2/Vs, whereas for a dose of 3.6×1014 Se+/cm2 the electrical activity was 36% with a sheet mobility of 760 cm2/Vs.
Infrared rapid thermal annealing of Si-implanted GaAs
Authors: Kuzuhara Masaaki , Kohzu Hideaki , Takayama Yoichiro
Published: February 2003

Conditions for post-implantation capless annealing of GaAs, called infrared rapid thermal annealing (IRTA) using halogen lamps, were investigated. Si-implanted GaAs (5×1012 cm−2, 150 keV) was annealed at temperatures ranging from 700 to 1100 °C for various annealing times. Annealed GaAs at 950 °C for 2–4 s shows about 75% electrical activation and 3700 cm2/Vs electron mobility without noticeable dopant diffusion and surface decomposition. Planar metal-semiconductor field-effect transistors (MESFET’s) fabricated on the active layer formed by this annealing method show that the technique is promising as a post-implantation annealing method for the fabrication of GaAs MESFET’s and GaAs integrated circuits (IC’s).
Superconductive tunneling into NbN deposited near room temperature
Authors: van Dover R. B. , Bacon D. D. , Sinclair W. Robert
Published: February 2003

We have developed the ability to deposit niobium nitride thin films routinely having a superconducting transition temperature of 14 K by dc reactive magnetron sputtering onto substrates held near room temperature (Ts <90 °C). This allows the use of conventional photoresist liftoff techniques for patterning. Pb-counterelectrode tunnel junctions formed on these films show excellent V-I characteristics, suitable for device applications and offering potential advantages over conventional Pb-alloy/Pb-alloy and Nb/Pb-alloy junctions. These high quality junctions are also suitable for tunneling investigations of superconductivity in the Nb-N system.
Temperature dependence of minority-carrier recombination velocities at grain boundaries in silicon
Authors: Seager C. H.
Published: February 2003

Measurements have been made of the temperature dependence of grain boundary minority-carrier recombination velocities in p-type polycrystalline silicon. This temperature dependence is found to be close to that observed for the dark resistance to across-boundary majority-carrier currents. We discuss this result in light of recent theoretical calculations of this effect.
High-field drift velocity of holes in inversion layers on silicon
Authors: Nelson D. F. , Cooper J. A. , Tretola A. R.
Published: February 2003

We report measurements of the room-temperature drift velocity of holes along the (100) Si-SiO2 interface (drift direction [011]) as obtained by a time-of-flight technique. Our measured values range up to 60% higher than previously reported values at comparable tangential and normal electric fields. An empirical equation that fits the low-field mobility and the high-field velocity as a function of tangential and normal fields is presented.
Physical properties of sputtered chalcogenide films with a variable content of Fe
Authors: Bornstein A. , Lewin I. , Lereah Y. , Croitoru N.
Published: February 2003

Thin films of the system (As13Te24Si27Sb18)1−xFex have been deposited by rf sputtering in argon from the powder of the corresponding composition. Structure and composition analyses have been performed using electron microscopy, electron diffraction, and electron probe x-ray microanalysis. Using these analyses, the amorphous structure and homogeneity of the material in the films have been verified. The Fe content x varies between 0 and 0.6. Electrical transport measurements have been performed at different temperatures between 77 and 400 K for 0≤x≤0.6, and the thermoelectric power measured at room temperature. Optical reflection and transmission measurements have also been made at room temperature for several values of x. From the conductivity measurements, thermoelectric power, and optical measurements, we found that the amorphous films show metallic behavior for x≥0.4. On the basis of the above measurements, we suggest an energy-band model which fits the experimental results.
Simultaneous formation of a shallow silicon p-n junction and a shallow silicide/silicon ohmic contact by an ion implantation technique
Authors: Tsaur B-Y. , Anderson C. H.
Published: February 2003

An ion implantation technique has been developed for the simultaneous formation of a shallow Si p-n junction and a shallow silicide/Si ohmic contact. A p-Si substrate is coated with a thin layer of W, then with alternating layers of Si and W. Bombardment of the coated substrate with As+ ions causes formation of WSi2 from the W and Si layers, dispersion of contaminant atoms at the interface between the first W layer and the substrate, and implantation of As atoms in the substrate. Subsequent thermal annealing produces a shallow WSi2/Si ohmic contact and simultaneously activates the implanted As donors to form a shallow p-n junction located directly below the contact. Mesa diodes with good junction characteristics have been fabricated by using this technique.
ac Josephson effect in small-area superconducting tunnel junctions at 604 GHz
Authors: Danchi W. C. , Habbal F. , Tinkham M.
Published: February 2003

We have measured the ac Josephson effect in small-area superconducting tunnel junctions at 604 GHz (λ=496 μm) using a resonant planar dipole antenna to couple the radiation into the junction. In a 176-Ω junction, we have observed up to the 7th Josephson step (at 8.75 mV), a performance comparable to that seen in point contacts. We also compare our data with the results of the RSJ model and of the Werthamer theory.
Wide aperture self-sustained discharge KrF and XeCl lasers
Authors: Watanabe S. , Endoh A.
Published: February 2003

A UV-preionized rare-gas halide laser with a large aperture to 7×7 cm2 and active volume of 4 ℓ has been operated at a high pressure regime of 5 atm. Beam profile measurements at the midplane between electrodes have shown the beam widths of 7 cm at a half-energy density both in KrF and XeCl. The improvement in discharge homogeneity and extension of the optical pulse duration have been obtained by the peaking of the discharge current with a small stray capacitance between the rail gap and the laser head as well as by the use of Ne rather than He as a buffer gas, resulting in the output energy of 13.8 J in XeCl and 5.0 J in KrF.
Low loss poly(methyl methacrylate-d5) core optical fibers
Authors: Kaino Toshikuni , Jinguji Kaname , Nara Shigeo
Published: February 2003

Low loss plastic optical fibers (POF’s) have been prepared employing poly(methyl methacrylate-d5) [P(MMA-d5)] core and fluorinated alkyl methacrylate copolymer cladding with attenuation losses of 41 and 55 db/km at wavelengths of 565 and 646 nm, respectively. The POF can allow short distance optical signal transmission, about 400 m at –36 dBm at rates up to 25 MHz, using a display grade GaAlAs light emission diode whose emission power at 660 nm and 20 mA of forward input current is 1 mW. The loss limit of this P(MMA-d5) core POF is estimated to be 22 dB/km at 565 nm.
Multikilowatt electron beams for pumping cw ion lasers
Authors: Rocca J. J. , Meyer J. D. , Yu Z. , Farrell M. , Collins G. J.
Published: February 2003

A glow discharge electron gun capable of producing a well collimated dc electron beam at energies between 1 and 6 keV and currents up to 1 A is described. The electron beam is produced in helium at pressures between 0.1 and 2 Torr without differential pumping. Beam generation efficiencies up to 80% have been measured. The electron guns are designed to pump cw ion lasers and are constructed to provide an optical path through the axis. Continuous-wave laser oscillation in Kr II has been obtained using electron-beam pumping of a He–Kr mixture.
Characterization of thermally nitrided silicon dioxide
Authors: Amano Jun , Ekstedt Tom
Published: February 2003

Characterization of low pressure (LP) thermal oxide films grown on Si(100) substrate and thermally nitrided LP oxide films were conducted by glancing angle backscattering with channeling. Film stoichiometry and the SiO2/Si interface properties were investigated by MeV He+ ion beams. LP oxide films exhibited stoichiometric SiO2 composition with one to two monolayers of nonregistered Si atoms at the interface. After thermal nitridation of these LP oxide films at 925 and 950 °C for 2 h, thin (oxy)-nitride layers on the oxide surface were observed. Also an additional one to two monolayers of nonregistered Si atoms were observed at the interface after the thermal nitridation. There were no observable changes in bulk stoichiometry of the LP oxide films after the thermal nitridation at 925 and 950 °C for 2 h.
Direct determination of atomic structure at the epitaxial cobalt disilicide on (111) Si interface by ultrahigh resolution electron microscopy
Authors: Gibson J. M. , Bean J. C. , Poate J. M. , Tung R. T.
Published: February 2003

Previously we reported that (111) CoSi2 on Si grown under UHV conditions is a true single-crystalline epitaxy. In this letter we report a determination of the atomic structure at the silicide-silicon interface in UHV reacted films. This determination was based on electron-microscopical data taken on an ultrahigh resolution instrument but included detailed consideration and modeling of the expected images. The atomic arrangement at this interface is best modelled with the silicide atom adjacent to the interface a metal one, with apparently only 5-fold local coordination, contrasted with the 8-fold coordination found in the bulk. The interface is perfectly regular, except at misfit dislocations, which have interesting core structure. Moreover, they provide indirect evidence for the ‘‘5-fold’’ model in the case of codeposited silicide films.
Fluctuations in tipping angles and delay times of simple superfluorescence
Authors: Lee C. T.
Published: February 2003

It is shown that the essential statistical properties of the initial tipping angle θ0 can be obtained through a simple model and can be calculated directly from the super-radiance master equation. Thus, the more elaborate models and the tedious task of solving the master equation can all be avoided, as far as θ0 is concerned. As a byproduct, the statistical properties of the delay time first calculated by Degiorgio are rederived in a more rigorous and much simpler way.
Mass-to-charge ratio and kinetic energy of positive ion emission accompanying fracture of a filled elastomer
Authors: Dickinson J. T. , Jensen L. C. , Park M. K.
Published: February 2003

We have recently discovered that the electron emission (EE) and positive ion emission (PIE) accompanying and following fracture of filled elastomers have substantial components emitted in coincidence. We exploit this result by using a time-of-flight method to measure the mass-to-charge ratio and kinetic energy of the PIE from the fracture of polybutadiene filled with glass beads.