bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient operation of Blumlein-discharge-excited XeCl laser
Authors: Jianwen Chen , Shufen Fu , Miaohong Liu
Published: February 2003

Experimental results of a Blumlein-discharge-excited XeCl laser are reported in this letter. The maximum output pulse energy was over 400 mJ. The overall efficiency and specific output energy were 1.7% and 5 Jl, respectively. Experiments have shown that the lasing spectrum of XeCl varied with the total pressure. With a total pressure of 500 Torr, 108 discrete laser lines including two new vibrational bands, (0,4) and (1.7), were obtained. The effects of the partial pressure of Xe, the Blumlein charging voltage, and the total pressure on the output energy were also investigated.
Electro-optical surface flashover measurements
Authors: Thompson J. E. , Lin J. , Mikkelson K. , Kristiansen M.
Published: February 2003

Electro-optical measurements of the electric field along solid insulator/vacuum interfaces have been made to determine the mechanisms associated with fast (ns) insulator flashover. Data showing the temporal and spatial performance of the insulator surface fields prior to and at flashover are presented. The results show that the intergap electric field is modified in a manner consistent with positive surface charging by field emitted electrons. The data also show that the enhanced intergap fields are reduced prior to flashover. Mechanisms consistent with this behavior are postulated.
Analysis of diode lasers with lateral spatial variations in thickness
Authors: Streifer W. , Burnham R. D. , Scifres D. R.
Published: February 2003

Diode lasers with active and/or cladding regions whose thicknesses vary spatially parallel to the p-n junction are analyzed. It is shown that lateral real-refractive-index waveguiding occurs and that a diffusion gradient exists which propels the injected charges into the lasing modal volume. Lateral mode patterns and thresholds are calculated and sensitivity to higher-order lateral mode oscillation is evaluated for various stripe widths and spreading resistances. Results are shown to agree well with experimental data.
Amplified oscillation in a slab-type optical directional coupler with an activated rhodamine 6G top layer
Authors: Sasaki K. , Fukao T. , Saito T. , Hamano O.
Published: February 2003

Guide-length-dependent amplified oscillation of coupled waves in a slab-type optical directional coupler covered with a triangular rhodamine 6G activated top layer was observed. This is an application of a thin-film optical-waveguide evanescent dye laser. Analysis using the complex coupling theory was compared with experiments.
Ultrasensitive detection of aromatic hydrocarbons by two-photon photoionization
Authors: Klimcak Charles , Wessel John
Published: February 2003

An optimized multiphoton photoionization detection system has been applied to monitor aromatic-hydrocarbon vapor density as a function of temperature. The density curves established for naphthalene by this procedure permit estimation of a detection limit of 5×104 molecules/cm3 in a nitrogen buffer gas. With slight modification this method woud be capable of single-molecule detection limits.
cw electro-optical characteristics and preliminary reliability of double-heterostructure GaAs-AlxGa1−xAs lasers grown by molecular beam epitaxy
Authors: Tsang W. T. , Hartman R. L. , Elder H. E. , Holbrook W. R.
Published: February 2003

The cw threshold currents and total forward series resistances of the proton-bombarded stripe-geometry lasers fabricated from GaAs-Al0.3Ga0.7As double-heterostructure (DH) wafers grown by molecular beam epitaxy (MBE) are at least as low as those similar-geometry lasers grown by liquid phase epitaxy. Yields for such laser diodes of ≳90% were obtained. Randomly picked diodes fabricated from an early MBE DH wafer having a 0.4-μm GaAs active layer have operated continuously at a constant output power of ∼2 mW/mirror in a ∼38 °C dry-nitrogen ambient for more than 13 000 h and are still operating.
Virtual-anode formation by an intense pulsed ion beam incident upon a magnetic barrier
Authors: Robertson Scott , Wessel Frank
Published: February 2003

An intense, pulsed, initially space-charge-neutral ion beam (100 kV, 1 kA, 600 nsec) has been propagated into a transversely oriented magnetic barrier. When the magnetic field is adjusted so that (ρiρe)1/2 ≪ a < ρi, a virtual anode is formed whose potential oscillates at ∼ωpi about a value near the ion accelerating potential, where a is the transverse beam dimension, ω pi is the ion plasma frequency, and ρe and  ρi are the electron and ion gyroradii. This behavior is similar to that predicted by Poukey and Rostoker for virtual cathodes.
Deep deuterium traps in Y-implanted Fe
Authors: Myers S. M. , Picraux S. T. , Stoltz R. E.
Published: February 2003

Ion-implanted Y in Fe is shown to trap deuterium with an enthalpy of ≃1.3 eV. This binding is the strongest yet reported for a hydrogen isotope in an Fe-based alloy. The trapping is attributed to a Y-vacancy complex, with the coupling being augmented by a Y-hydrogen chemical interaction.
Supersaturated solid solutions after solid phase epitaxial growth in Bi-implanted silicon
Authors: Campisano S. U. , Rimini E. , Baeri P. , Foti G.
Published: February 2003

The lattice location of Bi-implanted (100) Si after thermal treatment at 550 °C has been studed by a channeling effect technique. Supersaturated substitutional solid solutions are formed with a Bi concentration in excess of 500 times the maximum solid solubility. After growth good crystallinity is observed in the single-crystal Si host. Post-treatments at higher temperature up to 925 °C produce incipient precipitation of the Bi atoms. Both formation and stability of these solid solutions are accounted for by diffusion process. The proposed model has been tested using a high-diffusivity impurity Cu-implanted Si, which inhibits the regrowth of the Si hosts.
Cadmium–tin-oxide films deposited by dc reactive sputtering from a Cd-Sn alloy target
Authors: Miyata N. , Miyake K. , Yamaguchi Y.
Published: February 2003

Cadmium–tin-oxide films with high conductivity and high visible transmission were prepared by dc reactive sputtering from a Cd-Sn alloy target in an Ar-O2 atmosphere. The electrical and optical properties of these films were found to depend strongly uponthe oxygen concentration in an Ar-O2 atmosphere during deposition. Films with a lowest resistivity of 2.0×10−4 Ω cm and a highest transmission of 90% over the visible region have been obtained for a 6% oxygen concentration in an Ar-O2 atmosphere.
Preparation of conducting and transparent thin films of tin-doped indium oxide by magnetron sputtering
Authors: Buchanan M. , Webb J. B. , Williams D. F.
Published: February 2003

High-quality 800-Å-thick films of tin-doped indium oxide have been prepared by magnetron sputtering. It is shown that films with low resistivity (∼4×10−4 Ω cm) and high optical transmission (≳85% between 4000 and 8000 Å) can be prepared on low-temperature (40–180 °C) substrates with O2 partial pressures of (2–7)×10−5 Torr.
Time-resolved measurement of the electron-spin relaxation kinetics in GaAs
Authors: Seymour R. J. , Alfano R. R.
Published: February 2003

The spin relaxation and recombination kinetics in GaAs have been directly observed by time-resolved luminescence measurements. The spin relaxation time and initial spin alignment are separately determined in these measurements.
Thermoacoustic detection of electron paramagnetic resonance
Authors: Melcher R.L.
Published: February 2003

The detection of electron paramagnetic resonance absorption has been achieved using techniques similar to those used in the photoacoustic spectroscopy of solids. Magnetic field and amplitude modulation have been used in both resonant and nonresonant microwave spectrometers.
Heavy-ion beams produced by high-voltage pulse-powered plasma focus
Authors: Rhee M. J.
Published: February 2003

We report preliminary experimental studies of heavy-ion beams produced by a new type of plasma focus device which is powered by a fast high-voltage pulse of ∼500 kV, ∼20 kA, and ∼50 ns. A variety of ion species, either from solid materials or gases, were obtained and their beam characteristics, including charge states, energy spectrum, and emittance, were measured.
Dependence of trapping and segregation of indium in silicon on the velocity of the liquid-solid interface
Authors: Baeri P. , Poate J. M. , Campisano S. U. , Foti G. , Rimini E. , Cullis A. G.
Published: February 2003

The segregation phenomena of In-implanted Si have been observed following the melting and epitaxial regrowth of surface layers by pulsed ruby laser irradiation. The velocity of the liquid-solid interface on recrystallization has been varied from 1.8 to 5.2 m/s in two independent ways. Indium is observed to be trapped on substitutional sites, in excess of solid solubilities, or segregated in a thin surface layer. Trapping increases and segregation decreases as the interfacial velocity is raised. The complete depth profiles can be fitted with unique interfacial segregation coefficients which are velocity dependent. The material that has been segregated to the surface shows cell structure of approximately 100 Å diameter arising from lateral segregation due to constitutional supercooling. The cells are not present at velocities of 5 m/s. The critical dependence of In trapping and segregation on velocity in the range 2–5 m/s is interpreted in terms of interfacial residence times.
Blue laser action by the rare-gas halide trimer Kr2F
Authors: Tittel F. K. , Smayling M. , Wilson W. L. , Marowsky G.
Published: February 2003

Blue Kr2F excimer laser emission centered at 430 nm has been achieved in electron-beam-pumped high-density Ar/Kr/Nf3 mixtures. An output power of about 5 kW has been obtained. The spectral bandwidth is 25 nm for a simple two-mirror resonator with a potential tuning range between 380 and 480 nm.
Fiber-optic gyroscope with [3×3] directional coupler
Authors: Sheem Sang K.
Published: February 2003

It is proposed and experimentally demonstrated that a fiber-optic gyroscope using a [3×3] evanescent field-directional coupler as a beam splitter operates automatically at quadrature without the 1/2 π phase bias required by conventional gyroscopes with [2×2] beam splitters.
Electrostatic effects in inversion-layer metal-insulator-semiconductor solar cells
Authors: Lam Y. W. , Green M. A. , Davies L. W.
Published: February 2003

Several newer solar cell structures rely on charges in antireflection coatings to induce a charge layer along the surface of the semiconductor region of the cell. The present letter describes experimental results for time-dependent electrostatic effects in such devices, with particular reference to inversion-layer metal-insulator-semiconductor solar cells. It is shown experimentally that, over a period of several weeks, a charge layer builds up on the outside of the antireflection coating, which reduces its effectiveness as a charge inducer. Although devices can be designed to accomodate this effect, a preferable approach is to prevent this layer from building up.
Threshold and switching characteristics of a bistable nematic liquid-crystal storage display
Authors: Cheng Julian , Boyd G. D.
Published: February 2003

The electrical switching characteristics of a bistable liquid-crystal storage display is described, including the response times, switching mechanism, and a field dependence that exhibits several threshold effects. The origins and properties of these thresholds are discussed in relation to their utility in matrix-addressing applications.
Preparation and coercive force of melt-spun Pr-Fe alloys
Authors: Croat J. J.
Published: February 2003

Amorphous Pr1−x-Fex (0.45⩽x⩽0.90) alloys were prepared over a wide compositional range by melt spinning. Significant room-temperature intrinsic coercivities were found; a maximum of 2.8 kOe was found at composition x=0.6. At reduced temperature (20 K) coercivities as high as 60 kOe were observed. High-purity constituents were required to obtain amorphous samples over the composition interval 0.66⩽x⩽0.90.
Diffusion length determination in p-n junction diodes and solar cells
Authors: Arora N. D. , Chamberlain S. G. , Roulston D. J.
Published: February 2003

An experimental technique for determining the minority carrier diffusion length in the base region of Si p-n junction diodes and solar cells is described. The procedure is to operate the device in the photoconductive mode and to measure its photoresponse in the wavelength region near the energy gap. The ratio of incident light intensity to photocurrent is a linear function of reciprocal absorption coefficient for each wavelength; the slope of the set of points directly yields the diffusion length. In addition, a nonlinear least-squares analysis is also used to determine the diffusion length.
Photoelectromagnetic effect in amorphous silicon
Authors: Moore A. R.
Published: February 2003

The short-circuit current and open-circuit voltage of the photoelectromagnetic effect have been measured at room temperature in discharge-produced amorphous hydrogenated silicon (undoped, n type). From the magnitude and spectral distribution of the effect, the minority (hole) diffusion length and the hole μτ product are estimated to be 0.09 μm and 3×10−9 cm2/v, respectively, while the electron mobility is 5×10−2 cm2/v sec. From the photoconductivity the electron μτ product (majority carrier) was 8×10−8 cm2/v. Derived quantities are then hole mobility 9×10−3 cm2/v sec, hole lifetime 3×10−7 sec, electron lifetime 1.7×10−6 sec. The sign of the effect is normal. It does not show the inverted sign reported for the Hall effect in the dark.
cw far-infrared laser scattering from a laboratory plasma
Authors: Park H. , Peebles W. A. , Mase A. , Luhmann N. C. , Semet A.
Published: February 2003

The first far-infrared laser (λ0=1.22 and 0.447 mm) scattering experiment in a laboratory plasma is described. cw laser radiation is scattered at large angles (0 °–20 °) from ion acoustic waves launched in a low-density (ne ≃1010 cm−3) plasma thereby allowing detailed comparison with Langmuir probe data. Measurement of the wave-number resolution and studies of both linear and nonlinear ion waves are presented. Future application areas are briefly described.
Improvement of lattice site location of Ga implanted into Al after pulsed electron beam annealing
Authors: Hussain T. , Geerk J. , Ratzel F. , Linker G.
Published: February 2003

The effect of pulsed electron beam annealing (PEBA) on the lattice location and impurity distribution of Ga ions implanted into Al single crystals has been compared with the thermal annealing behavior of this ion/target system. While with thermal annealing only slight improvement of the lattice site occupation was observed after PEBA within experimental accuracy, all implanted impurities occupied perfect lattice sites. In the thermal treatment the Ga atoms partially diffused out of the implanted region; with PEBA, however, the implanted impurity distribution remained unchanged.
Model for nonequilibrium segregation during pulsed laser annealing
Authors: Wood R. F.
Published: February 2003

Highly nonequilibrium thermodynamic processes occur during the ultrarapid recrystallization characteristic of pulsed laser annealing. Values of interface segregation coefficients are observed to differ from equilibrium values by as much as three orders of magnitude and equilibrium solubility limits may be exceeded by similar magnitudes. In this letter, a model is developed which accounts quantitatively for these effects.
Orientation effect on planar GaAs Schottky barrier field effect transistors
Authors: Lee C. P. , Zucca R. , Welch B. M.
Published: February 2003

Orientation effects on planar GaAs Schottky barrier field effect transistors (MESFET’s) have been found. Device characteristics of FET’s parallel to both [110] directions and both [100] directions are compared. Dependence of the characteristics on gate length has been measured for FET’s oriented in two perpendicular [110] directions. Preferential lateral diffusion is proposed to be the reason underlying these phenomena.
Improved efficiency of CdSe photoanodes by photoelectrochemical etching
Authors: Tenne R. , Hodes G.
Published: February 2003

By illuminating a CdSe photoanode in an electrolyte in which it is photoelectrochemically unstable, a selective etching of the CdSe to a matte black surface occurs with formation of small pits (≈1000 Å diameter). This photoelectrochemical etch was found to improve the output characteristics of the CdSe-polysulfide photoelectrochemical cell through an increase in short-circuit current (SCC) for single-crystal CdSe, and an increase in fill factor and SCC for polycrystalline CdSe, where the improvement is more marked. This increase could be explained only partly through decreased reflectivity of the surface, and is probably connected with removal of (near) surface recombination centers.
An x-ray resonator based on successive reflections of a surface wave
Authors: Bremer J. , Kaihola L.
Published: February 2003

Total reflection of x rays is considered by expanding the Fresnel coefficient in the grazing angle of incidence, assumed to be much less than the critical angle. A study is made of resonatorlike mirror systems that are capable of changing the direction of the incoming wave by 2π rad. The possibility of modulating the refractive index n=1−δ−iβ and the influence of scattering losses are briefly discussed. A high number of successive reflections may lead to a nonzero limit exp(−π√2 βδ−3/2) for the relative intensity. It is usually more important to have a ’’horizontal’’ reflectivity curve than a high critical angle.
The structure of ultrathin oxide on silicon
Authors: Krivanek Ondrej L. , Mazur Jerzy H.
Published: February 2003

30-Å-thick oxide on silicon has been examined in cross section by high-resolution electron microscopy. The oxide thickness was uniform to within 5 Å, even though the oxide undulated up to 8 Å in height and with about 50 Å periodicity.
Si and Ge (111) surface structures after pulsed laser annealing
Authors: Zehner D. M. , White C. W. , Ownby G. W.
Published: February 2003

Pulsed laser irradiation of (111) oriented single-crystal surfaces of Si and Ge is shown to result in the production of (1×1) surface structures as determined by low-energy electron diffraction. These metastable surface structures are obtained in the absence of any stabilizing impurities. The temperature range over which these surface structures are stable has also been determined. These results are compared with those obtained by conventional sputter-anneal treatments.
Schottky barrier formation by laser irradiation processing
Authors: Yang E. S. , Wu C. M. , Vollmer H. J. , Sedgewick T. O. , Hodgson R. T.
Published: February 2003

A Schottky barrier is fabricated with a silicon-aluminum-silicon structure by the irradiation of either a pulsed or cw laser. The completed diodes have a large barrier height (1 eV) and good rectifying properties.
Plasma etching characteristics of sputtered MoSi2 films
Authors: Chow T. P. , Steckl A. J.
Published: February 2003

Plasma etching of sputtered MoSi2 films using CF4/O2 mixtures was studied in a barrel-type reactor. The etch rate in pure CF4 was very low (≲100 Å/min) and insensitive to applied power. The addition of a small percentage (<10%) of O2 dramatically increased the etch rate. For CF4/4% O2, and etch rate of ∼920 Å/min was measured at 100 W. A near-linear etch rate dependence on rf power was observed, indicating that the controlling factor is the generation rate of etching radicals. For CF4/8% O2, the etch rate nearly doubled and showed saturation at high rf power, indicating the increased role of the surface reaction rate. Postdeposition anneal results in a 10–20% decrease in etch rate. An etch rate selectivity of 14–22 for MoSi2 vs SiO2 and of 2–3 for doped poly-Si vs MoSi2 were measured.
Energy absorption and transport in layered targets irradiated by a relativistic electron beam
Authors: Imasaki K. , Miyamoto S. , Higaki S. , Nakai S. , Nishihara K. , Yamanaka C.
Published: February 2003

The dynamic behavior of a blowoff plasma of a thin-layered target was observed optically by shadowgraphy. The results are explained by means of ablative and explosive models. Experimental evidence of highly efficient beam coupling which includes hydrodynamic driving of the plasma is presented.
Use of a concentric-arc grating as a thin-film spectrograph for guided waves
Authors: Tien P. K. , Capik R. J.
Published: February 2003

We describe a thin-film spectrograph for guided optical or surface acoustic waves which involves wave diffraction from a concentric-arc grating in a slab waveguide. In this spectrograph, diffracted waves in the waveguide form spectra of various orders which are in focus on a circle similar to the Rowland circle of an ordinary grating spectrograph. The optics described above may also be used for acousto-optic deflection, integrated optic spectrum analyzers, and other applications.
Hall measurements and grain-size effects in polycrystalline silicon
Authors: Ghosh Amal K. , Rose Albert , Maruska H. Paul , Eustace Daniel J. , Feng Tom
Published: February 2003

The effects of grain size on Hall measurements in polycrystalline silicon are analyzed and interpreted, with some modifications, using the model proposed by Bube. This modified model predicts that the measured effective Hall voltage is composed of components originating from the bulk and space-charge regions. For materials with large grain sizes, the carrier concentration is independent of the intergrain boundary barrier, whereas the mobility is dependent on it. However, for small grains, both the carrier density and mobility depend on the barrier. These predictions are consistent with experimental results of mm-size Wacker and μm-size neutron-transmutation-doped polycrystalline silicon.
A noise spectrum described by a distribution in time constants
Authors: Suh C. H. , van der Ziel A.
Published: February 2003

We have found spectra of the form (A/f )[1−(2/π)tan−1(ωτ0)] in GaAs Schottky gate field effect transistors at low frequencies. Such spectra were predicted by van der Ziel and by du Pre in 1950 and by McWhorter in 1955, and are attributed to a process governed by a distribution in time constants.
GaAs integrated circuits by selected-area molecular beam epitaxy
Authors: Metze G. M. , Levy H. M. , Woodard D. W. , Wood C. E. C. , Eastman L. F.
Published: February 2003

Working GaAs integratted logic elements have been fabricated using selected-area molecular beam epitaxy. Thermally grown native oxides ∼250 Å thick have been used to define regions of single-crystalline device-quality GaAs in a matrix of semi-insulating polycrystalline GaAs. The planarity of this process and the inherent resistivity of the polycrystalline GaAs ( ρ≳105 Ω cm) have been used in the fabrication of working NAND and NOR logic gates (Schottky diode/field-effect transistor logic).
A free-electron laser pump produced by magnetic diffusion
Authors: Jacobs K. D. , Shefer R. E. , Bekefi G.
Published: February 2003

Magnetic diffusion through a spatially periodic assembly of metal conductors yields a large-amplitude pump for use in free-electron lasers. Experiments and computations which test the performance of the pump are presented.
Noise characteristics of semiconductor laser diodes coupled to short optical fibers
Authors: Chen Y. C.
Published: February 2003

The noise character of semiconductor laser diodes coupled to short optical fibers is found to exhibit increased noise power peaked on the low-frequency side of the intrinsic noise profile. The phenomenon has been observed in laser diodes with and without self-sustained oscillations below 1.8 GHz and can be explained as a downshift in frequency of the intrinsic resonance due to the coupling of the laser cavity and the short optical fiber. This effect may introduce higher noise at frequencies where light-wave communication systems operate even though the laser diodes themselves are very quiet.
A double-electrode-pair-pulsed laser
Authors: Fox Jay A.
Published: February 2003

A transversely excited atmosphere carbon dioxide laser with two sets of electrode in the optical cavity is described. The device produces high-intensity pulse pairs with time separations as short as 20×10−6 sec. This is accomplished without high-speed gas flow.
Hole traps in thermal silicon dioxide introduced by chlorine
Authors: Manchanda L. , Vasi J. , Bhattacharyya A. B.
Published: February 2003

Hole traps in thermal silicon dioxide grown in the presence of trichloroethylene (TCE) have been studied. Addition of TCE during oxidation results in shallow hole traps in the SiO2. The energetic location of these traps is ⩽1.0 eV with respect to the valence-band edge of the silicon dioxide. The trap density and its centroid are functions of the amount of TCE added during the oxide growth. For a particular molar concentration of TCE, the value of charge centroid is approximately equal to the value of centroid of the chlorine profile in the oxide. We postulate that incorporation of chlorine atoms in the SiO2 network results in additional shallow hole traps. A qualitative model is presented for the nature of these traps. A charge transfer mechanism via these traps is proposed for sodium passivation in chlorine-incorporated oxides.
Noise phenomena in Josephson junctions
Authors: Huberman B. A. , Crutchfield J. P. , Packard N. H.
Published: February 2003

We suggest that the reported noise-rise phenomenon observed in Josephson oscillators can be understood in terms of the full nonlinear and deterministic junction dynamics. We show that the drive damped pendulum equation describing the junction behavior exhibits chaotic solutions associated with the appearance of strange attractors in phase space. These results are relevant to the general problem of turbulent behavior of anharmonic systems.
Reliable passive mode locking with slow Q switching
Authors: Marconi Mario Carlos , Martinez Oscar Eduardo , Diodati Francisco Piero
Published: February 2003

An electro-optic modulator (EOM) has been added to a passive mode-locked Nd:glass laser in order to slow Q-switch the cavity. This guarantees that the laser will work near threshold even if the gain of the laser medium or the losses change from shot to shot. The losses at the EOM are used as the output coupling. This new configuration allows more reliable operation of the system.
Synergism between strain and neutron irradiation in filamentary Nb3Sn conductors
Authors: Snead C. L. , Suenaga M.
Published: February 2003

The critical temperatures Tc of Nb3Sn and Nb3(SnGa) monofilamentary wires have been measured as a function of neutron fluence to 1.3×1019 n/cm2 (E≳1 MeV). The bronze overlayer was removed and Tc remeasured. The differences between the bronze-on and -off conditions, a measure of the ’’prestrain effect’’ on the A15 layer, were seen to increase with increasing fluence. This enhancement of the prestrain effect is attributed to buckling of the Nb chains in the vicinity of Sn sites on the Nb chains (antisite disorder), the amount of buckling with the bronze on being greater because of the prestrain. The synergism between irradiation and prestrain is concluded to be a degrading factor in the operation of magnetically confined fusion reactor magnets unless the prestrain (compressive) is completely compensated by the externally applied (tensile) strains.
A lossless, passive isolator for optically pumped far-infrared lasers
Authors: Mansfield D. K. , Semet A. , Johnson L. C.
Published: February 2003

A lossless, passive technique which isolates the pump and the far-infrared cavities in an optically pumped far-infrared laser system has been applied successfully. The isolator consists of a polarizer and a quarter-wave plate. Pumping is accomplished with a circularly polarized beam, and the resulting circular polarization of the far-infrared output stability without sacrifice of either power or mode quality.
Lasing characteristics of iodine monofluoride
Authors: De Young R. J.
Published: February 2003

Lasing has been observed at 491 and 484 nm from iodine monofluoride in mixtures of He/CF3I/NF3. The emission and lasing spectrum were investigated as well as conditions for optimum lasing. Optimum lasing at E/N of 1.8×10−16 occurred at 1277/0.65/2 Torr with an output reflector of 32% transmission. A media gain of ∼ 2% per cm was measured at optimum lasing conditions. Passivation with CF3I was found to be important for longer-lifetime operation.
Nuclear-induced XeBr* photolytic laser model
Authors: Wilson J. W.
Published: February 2003

Parameters for a photolytically pumped alkyl lasant iodide gas by the nuclear-induced XeBr* excimer fluorescence are calculated according to a detailed kinetic model. High gain on the atomic iodine 2P1/2 state is estimated and 100-mJ pulses with an average power output on the order of 1 kW appear possible.
Scanning-electron-microscope observations of propagating acoustic waves in surface acoustic wave devices
Authors: Eberharter G. , Feuerbaum H.P.
Published: February 2003

We report for the first time the observation of propagating acoustic waves from constant-overlap and apodized interdigital transducers on y-cut LiNbO3, obtained by a scanning electron microscope using the stroboscopic voltage contrast. It is the most convenient and fastest method known today of observing directly on screen the complex radiation patterns of interdigital transducers on piezoelectric substrates.
Electrical properties of cw laser-annealed ion-implanted polycrystalline silicon
Authors: Roulet M. E. , Dutoit M. , Lüthy W. , Affolter K.
Published: February 2003

Resistivity and Hall measurements were performed on O.3-μm-thick polycrystalline-silicon film after implantation with 1012–5×1014 boron or phosphorus ions/cm2 and annealing with a cw Kr-ion laser (green lines). The laser-induced increase of grain size drastically alters the resistivity and Hall mobility. The largest effect occurs for average doping levels between 4×1016 and 1018 cm−3, where resistivity decreases by up to four and mobility increases by up to two orders of magnitude, compared with unirradiated parts of the same wafers. Values approaching those of single crystals are obtained. The results are interpreted in terms of a published grain-boundary trapping model.
UV laser-induced deposition of metal films
Authors: Coombe R. D. , Wodarczyk F. J.
Published: February 2003

KrF and XeCl excimer lasers have been used to induce the localized deposition of films of zinc and magnesium on a variety of transparent and absorbing substrates. The metal atoms are derived from flows of the pure metals. The films, which have thicknesses up to several microns, are produced only in the area of the substrate irradiated by the laser. It is hypothesized that UV radiation activates the substrate surface for film nucleation by desorbing species (e.g., hydrocarbons) which inhibit adhesion.
Verification of elastic-wave static displacement in solids
Authors: Cantrell John H. , Winfree William P.
Published: February 2003

The solution of the nonlinear differential equation which describes an initially sinusoidal finite-amplitude elastic wave propagating in a solid contains a static-displacement term in addition to the harmonic terms. The static-displacement amplitude is theoretically predicted to be proportional to the product of the squares of the driving-wave amplitude and the driving-wave frequency. We report the first experimental verification of the elastic-wave static displacement in a solid ([111] direction of single-crystal germanium) and find agreement with the theoretical predictions.
High ionic conductivity of Na-βGa2O3 thin film.
Authors: Miyauchi Katsuki , Kudo Tetsuichi , Suganuma Tsuneo
Published: February 2003

Sodium β-gallate thin films are prepared by rf sputtering and subsequent heat treatment. These thin films exhibit ionic conductivity as high as 4.2×10−2 Ω, cm−1 at 3000C and 7.0×10−6 Ω cm−1 at room temperature. Their ionic conductivity above 2000 C is only one order of magnitude less than that of single crystals. The activation energy of ionic conduction is 0.23 eV, that is, almost the same as that of single crystals. This ionic conductivity is high enough to be applied to thin-film devices of solid electrolytes.
X-ray-absorption fine-structure measurement using a laser-compressed target as a source
Authors: Yaakobi B. , Deckman H. , Bourke P. , Letzring S. , Soures J. M.
Published: February 2003

Laser-compressed targets are shown to be a powerful source of x-ray continuum suitable for (dynamic) absorption fine-structure studies. A 50-psec six-beam laser pulse of peak power 2 TW produced a continuum x-ray fluence of 2.5×1015 photons/keV at 2.6 keV (of duration∼100 psec). We used this source to record the sulfur K-edge absorption fine structure in diffraction from a gypsum crystal.
Laser light absorption in long-pulse high-irradiance experiments
Authors: Arad B. , Eliezer S. , Gazit Y. , Jackel S. , Karmi Y. , Loebenstein H. M. , Zigler A.
Published: February 2003

The fractional absorption of 1.06-μm-wavelength, 3-nsec-duration laser pulses in gold and aluminum targets was measured over the intensity range 1013–1016 W/cm2. Absorption was found to be z dependent with the stimulated scatter being independent of z. Absorption at the higher intensities was found to be limited by increased stimulated scatter rather than by decreased efficiency of the absorption mechanisms.
Plasma anodization of Hg1−xCdxTe
Authors: Nemirovsky Y. , Goshen R.
Published: February 2003

A new plasma oxidation process for forming oxide films on Hg1−xCdxTe is described. Electrical measurements on metal-insulator-semiconductor devices employing the native oxide are presented. The oxide films have a relatively low fixed surface charge density of (1–3)×1011 e cm−2 and in this respect are superior to oxides growth by chemical anodization. For insulators which are a combination of 300-Å native oxide and 2000-Å ZnS the measured flat-band voltages are −0.5 and −2.5 V for n-t and p-type substrates, respectively. The measured work-function difference is −1.7 V for indium gate structures and the relative dielectric constant of the oxide is 13. The capacitance-voltage and current-voltage characteristics indicate an interface well suited for devices such as photoconductors, photovoltaic diodes, and charge-coupled devices.
Fast photoconductive detector using p-In0.53Ga0.47As with response to 1.7 μm
Authors: Degani J. , Leheny R. F. , Nahory R. E. , Pollack M. A. , Heritage J. P. , DeWinter J. C.
Published: February 2003

Photoconductive detectors, fabricated from p-type In0.53Ga0.47As using strip-line techniques, exhibit rise and fall times of 45 and 70 psec FWHM. This performance is consistent with a peak electron drift velocity of 2.1×107 cm/sec at a field of ∼3.5 kV/cm and represents the fastest reported detector response for the 1.0–1.7-μm wavelength range.
Semimetallic InAs-GaSb superlattices to the heterojunction limit
Authors: Chang L. L. , Kawai N. J. , Mendez E. E. , Chang C.-A. , Esaki L.
Published: February 2003

Superlattices of InAs-GaSb have been investigated with layer thicknesses ranging from the onset of the semiconductor-semimetal transition (<100 Å) to the heterojunction limit (≳1000 Å). Pronounced Shubnikov–de Haas osicillations have been observed throughout the entire semimetallic regime which are shown to be associated with the ground-electron sub-bands, yielding energies of the Fermi level in agreement with those calculated from electron transfers.
Enhanced plasma oxidation at low temperature using a thin solid electrolyte film
Authors: Gourrier S. , Dimitriou P. , Theeten J. B. , Perrière J. , Siejka J. , Croset M.
Published: February 2003

Low-temperature anodic oxidation in a ’’cold’’ plasma (multipole) of metals like Al or Ta through a thin calcia-stabilized zirconia (CSZ) film is possible. Thick (≳300 nm) stoichiometric metal oxides are formed under the CSZ with high growth rates (20–30 nm/min). Anodization of bare metals under similar plasma conditions leads to very low oxidation rates (<1 nm/min). The CSZ film, which acts as a selective oxygen filter, has thus greatly enchanced the oxidation rate. Low-temperature (<50 °C) plasma anodization of silicon (typical rates 2–3 nm/min) is also possible through a thin CSZ film.
Measurements of hot-electron conduction and real-space transfer in GaAs-AlxGa1−xAs heterojunction layers
Authors: Keever M. , Shichijo H. , Hess K. , Banerjee S. , Witkowski L. , Morkoç H. , Streetman B. G.
Published: February 2003

Measurements of the current-voltage characteristics of GaAs-AlxGa1−xAs heterojunction layers are reported. The experimental results are consistent with the idea of real-space transfer of the electrons out of the GaAs into the AlxGa1−xAs under hot-electron conditions. Current saturation and negative differential resistance are observed as predicted by Monte Carlo simulations.
Accelerated aging test of InGaAsP/InP double-heterostructure laser diodes with single transverse mode
Authors: Imai H. , Morimoto M. , Ishikawa H. , Hori K. , Takusagawa M. , Wakita K. , Fukuda M. , Iwane G.
Published: February 2003

Aging tests of InGaAsP/InP double-heterostructure (DH) laser diodes with single transverse mode have been performed at 50 and 70 °C under constant optical power operation. The devices were self-aligned-structure DH laser diodes bonded with AuSn-alloy solder. Samples for 3-mW/facet operation at 50 °C are operating at over 5000 H, those for 5-mW/facet operation at 50 °C are operating at over 4500 H, and those for 3-mW/facet operation at 70 °C are operating at over 3500 H. Far-field patterns parallel to the junction plane in these samples do not change in this aging. Averaged increasing rates of the driving current to maintain the specified optical power are 1.8×10−6/H for 3-mW operation at 50 °C, 48×10−6/H for 5-mW operation at 50 °C, and 1.3×10−5/H for 3-mW operation at 70 °C.
Suppression of optical beam filamentation in plasmas and saturable dielectrics
Authors: Felber F. S.
Published: February 2003

The first use of a variational approach to analyze the growth of a localized filament on an optical plane wave in a nonlinear medium shows that saturation of the nonlinearity of the medium by the wave can suppress filamentation of the wave. Applications may include lossless filters that remove hot spots from beams or convert multimode beams to single mode.
The mechanism of Schottky-barrier formation in polyacetylene
Authors: Waldrop J. R. , Cohen Marshall J. , Heeger A. J. , MacDiarmid A. G.
Published: February 2003

An investigation of metal-polyacetylene contacts by using x-ray photoemission spectroscopy is reported. For undoped p-type polyacetylene, Mg metal formed a rectifying contact with a Schottky-barrier height of ≳0.6 eV; Au metal formed a pure ohmic contact. Changes in band bending in the polyacetylene with metal deposition were directly observed by x-ray photoemission spectroscopy and correlated with I-V transport measurements. Our results indicate that the mechanism for Schottky-barrier formation in polyacetylene is the electrostatic match of work functions at the metal-polyacetylene interface and that there are no intrinsic or extrinsic filled interface states within the polyacetylene band gap.
Ion implantation in Si using a high-density CO2 laser-produced boron plasma flux
Authors: Silfvast W. T. , Tell B.
Published: February 2003

Implantation of boron ions in n-type Si wafers was achieved with the plasma flux from a CO2 laser-produced boron plasma. Junction depths of up to 0.4 μm and peak concentrations of boron atoms of greater than 1020 cm−3 were achieved with a single 7-J CO2 TEA laser pulse. The measured ion energies of ∼1 keV in the boron flux resulted both in the high concentration near the surface and also the anomalous deep penetrating tail.
Microdefects distribution in Czochralski-grown silicon crystals
Authors: Ohsawa A. , Honda K. , Shibatomi S. , Ohkawa S.
Published: February 2003

Striated microdefect distribution (swirl defects) are formed by the heat treatment in Czochralski-grown silicon crystals. The striation observed by etching has two period components 1–2 mm and 300–500 μm along growth direction. The corresponding microdistribution of oxygen was examined by the scanning infrared absorption method with the collimated beam of 100 μm in diameter. The results show that the distribution with the period of 1–2 mm was only observed, but not the microdistribution with the period of 300–500 μm. It is proposed from the results that microdefects are originated at a high oxygen-concentration region from the nuclei which were introduced in a striated pattern with the period of 300–500 μm during crystal growth. The nucleus is not interstitial oxygen itself.
Optical absorption coefficients from short-circuit current measurements of solar cells
Authors: Basol Bulent M. , Stafsudd Oscar M.
Published: February 2003

A technique is described to determine the optical absorption coefficients of semiconductor films. This technique uses the spectral response of solar cells formed on these films. Under certain conditions the photogenerated current in a back-wall solar cell is a simple exponential function of the absorption coefficient and the thickness of the device. As a result the optical absorption coefficients can be obtained from the slopes of log (I) versus thickness curves at different wavelengths. The technique was applied to electrochemically deposited CdTe and gave results that are in agreement with other published work.
Spatially delineated growth of metal films via photochemical prenucleation
Authors: Ehrlich D. J. , Osgood R. M. , Deutsch T. F.
Published: February 2003

Photodissociation of a thin surface layer of metal-alkyl molecules with a UV laser is shown to be an effective technique for predisposing the irradiated region to subsequent film growth. The efficacy of this technique, termed ’’prenucleation,’’ can be understood using a simple mathematical model for the early stages of thin-film formation. The technique has applications in direct writing of microstructures.
Simultaneous modulation of electron and hole conductivity in a new periodic GaAs doping multilayer structure
Authors: Ploog K. , Künzel H. , Knecht J. , Fischer A. , Döhler G. H.
Published: February 2003

A new periodic n-p doping multilayer structure in GaAs grown by molecular beam epitaxy is presented, in which the concentration of electrons and holes in the respective doping regions and thereby the conductivity can be varied simultaneously by more than 1012 carriers cm−2 per layer by an external potential difference eUnp applied between the constituent n- and p-type layers. The intriguing properties of this prototype of a bulk multijunction field-effect transistor structure result from a suppression of the direct electron-hole recombination by a space-charge potential periodically modulated in the direction of layer growth. The observed data are in excellent agreement with the calculated characteristics using the preselected design parameters of the structure.
A new set of space-averaged time-dependent equations for laser systems
Authors: Last (Lyast) I. , Baer M.
Published: February 2003

The semiclassical equations of a three-level laser system are considered in this work. By applying the rotating wave approximations, a new simplified set of space-averaged, but time-dependent equations were obtained. The equations were found to be reliable for a finite polarization decay constant and in the range of weak and intermediate pumping intensities (pulsed) not larger than 1011 sec−1.
A Schottky-barrier-delineated stripe structure for a GaInAsP-InP cw Laser
Authors: Bouley J. C. , Chaminant G. , Charil J. , Devoldere P. , Gilleron M.
Published: February 2003

A new stripe geometry for cw GaInAsP-InP layers is presented. The laser consists of a stripe contact defined on the In0.53 Ga0.47 As cap layer of a conventional double heterostructure. It is surrounded by two lateral-reverse-biased Schottky diodes fabricated onto the p-type confinement layer. These lasers have a threshold curent of 100 mA for 320-μm-long and 20-μm-wide stripes and operate in the zero-order transverse mode.
Laser chemical technique for rapid direct writing of surface relief in silicon
Authors: Ehrlich D. J. , Osgood R. M. , Deutsch T. F.
Published: February 2003

High-resolution etching of single-crystal and polycrystalline silicon has been demonstrated using an argon-ion laser to control microscopic chemical reactions. Gas-phase Cl2 or HCl is used in reactions initiated both by surface heating and by molecular photolysis. Features smaller than 5 μm and etch rates greater than 6 μm/s have been obtained. The process seems immediately suitable for a variety of problems in integrated-circuit fabrication.
Deliquescence as the mechanism for strong dust adhesion
Authors: Nosker R. W. , DiMarco L. A. , Williams Richard
Published: February 2003

We have used a fine-scale probe to explore large-area substrates systematically and to determine the strength of adherence of dust particles. A small fraction of the particles becomes strongly adherent as a result of cycling the relative humidity above and below 80%. These particles are responsible for wear and malfunction in fine mechanical systems. We show that the mechanism by which most of these particles are cemented to the substrate involves solution and redeposition of water soluble salts.
Simple rate equation model for hypothetical doubly stimulated emission of both photons and phonons in quantum-well lasers
Authors: Kroemer Herbert
Published: February 2003

The dissipation processes by which electrons and holes lose energy after being trapped in quantum wells might, in a sufficiently heavily pumped quantum well laser, lead to the buildup of such a high phonon population that phonon-assisted laser action by doubly stimulated emission of photons and phonons acquires a higher gain than unassisted laser action. The resulting mode switching exhibits a pronounced hysteresis with pump rate, which should be a characteristic identifying feature of phonon-assisted laser action.
Effect of turbulence-induced correlation on laser remote sensing errors
Authors: Killinger D. K. , Menyuk N.
Published: February 2003

Using a 10.6-μm dual-laser differential-absorption laser remote sensing system, we have measured the short- and long-term temporal correlation of the returns from topographic targets and retroreflectors in order to investigate the effect of atmospheric turbulence on laser remote sensing measurement errors. Our results quantify the improvement obtained through use of a dual-laser system compared to that of a single-laser system and are in good agreement with those predicted by a theory which considers the effect of partial temporal correlation on the resultant measurement error.
Reduced temperature dependence of threshold of (Al,Ga)As lasers grown by molecular beam epitaxy
Authors: Pawlik J. R. , Tsang W. T. , Nash F. R. , Hartman R. L. , Swaminathan V.
Published: February 2003

We report pulsed-current thresholds for stripe-geometry lasers fabricated from some ternary active layer molecular beam epitaxially grown wafers, which are nearly temperature independent over a ≊100 °C range. Lasers from one such wafer, pulse-operated over the practically important temperature range about room temperature, exhibit only a 3-mA threshold decrease in going from −10 to +20 °C and only a 3-mA increase in going from 20 to 50 °C. Fitting the data over small temperature intervals using the commonly observed exponential function for the temperature dependence of threshold (I = I0 exp(T/T0)) results in negative, infinite, and large positive values (⩾300K) for T0, as the temperature is increased from −10 to 75 °C. Lasers with such a range of threshold insensitivity may reduce pattern-dependent effects and may have significant practical implications for the simplification of the feedback circuitry used to maintain the pre-bias operating current in laser transmitters. Data examined over the temperature interval −55 to 260 °C show that thresholds for the anomalous temperature insenstive devices are everywhere greater than or equal to the thresholds of comparable normal devices. Independent data tends to rule out a resistive shunt model as well as a mechanism based upon the inhomogeneous incorporation of aluminum and/or dopants in the active layer. Available evidence suggests that the explanation is related to changes occurring in a normally present nonradiative mechanism.