bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of the germanium oxidation process by aluminum adatoms
Authors: Katnani A. D. , Perfetti P. , Zhao Te-Xiu , Margaritondo G.
Published: February 2003

Ultrathin (nominal thickness 0.4–2 Å) aluminum overlayers dramatically increase the oxidation rate of Ge(111) surfaces. The resulting chemisorption phase does not correspond to any of the known oxides of Ge or Al. This new phase is likely to provide a stable interface between Ge and GeO2.
High performance all-sputter deposited Cu2S/CdS junctions
Authors: Thornton John A. , Anderson W. W.
Published: February 2003

Thin-film Cu2S/CdS solar cells have been fabricated in a multisource chamber by using magnetron reactive sputtering to deposit the Cu2S and CdS layers. An analysis of junction current voltage, log Jsc vs Voc (where Jsc is the short circuit current and Voc is the open circuit voltage) and capacitance versus voltage measurements indicates that the junctions have very good quality, with diode ideality factors of near unity, and interface recombination velocities of about 2×105 cm/s. Cells without antireflection coatings have yielded Jsc = 12.2 mA/cm2, Voc = 0.53 V, fill factors of 0.62, and efficiencies of ∼4% in their as-deposited state. The cells show that Cu2S/CdS junctions equivalent to those formed by the topotaxial ion exchange method can be formed by sequential all-vacuum deposition of CdS and Cu2S, and that magnetron sputtering does not cause damage that compromises their electrical performance.
Calculation of carrier and lattice temperatures induced in Si by picosecond laser pulses
Authors: Lietoila A. , Gibbons J. F.
Published: February 2003

A previously presented computer model was used to calculate melt thresholds and carrier temperatures in crystalline silicon subjected to 20-ps laser pulses at 532 nm. The energy relaxation time of hot carriers was a variable parameter. A thermalization time of 1 ps yields results which are in very satisfactory agreement with published experimental data: the melt threshold is 0.19 J/cm2 and the maximum carrier temperature for the threshold pulse is 5000 K.
Amorphous silicon photovoltaic detectors for guided-wave optics
Authors: Yumoto J. , Yajima H. , Seki Y. , Shimada J. , Nakajima M.
Published: February 2003

Amorphous silicon photovoltaic detectors were made on 7059 glass waveguides and Ti-indiffused LiNbO3 waveguides. The rise as well as the fall time is 350 ns and the dynamic range is more than 36 dB.
Efficient H2 Raman conversion of long-pulse XeF laser radiation into the blue-green region
Authors: Komine H. , Stappaerts E. A. , Brosnan S. J. , West J. B.
Published: February 2003

Efficient Raman conversion of microsecond pulse XeF laser radiation into the blue-green region via the second Stokes shift in hydrogen has been demonstrated using a Raman oscillator-amplifier scheme. Strong depletion of the pump and the first Stokes radiation accompanied by a dominant second Stokes output was observed for the first time.
Monolithic integration of a GaAlAs buried-heterostructure laser and a bipolar phototransistor
Authors: Bar-Chaim N. , Harder Ch. , Katz J. , Margalit S. , Yariv A. , Ury I.
Published: February 2003

A GaAlAs buried-heterostructure laser has been monolithically integrated with a bipolar phototransistor. The heterojunction transistor was formed by the regrowth of the burying layers of the laser. Typical threshold current values for the lasers were 30 mA. Common-emitter current gains for the phototransistor of 100–400 and light responsivity of 75 A/W (for wavelengths of 0.82 μm) at collector current levels of 15 mA were obtained.
X-ray interference by division of wave front—A new x-ray interferometer
Authors: Chang Shih-Lin , Campos Cicero
Published: February 2003

An x-ray interference pattern is observed for the first time by division of the wave front at one piece of a single crystal. The (220) reflection from a V-shaped silicon crystal and a synchrotron radiation source are used. The crystal, acting simultaneously as a beam splitter, mirror, and analyzer, represents a novel single-leaf x-ray interferometer.
Observation of linewidth broadening in (GaAl)As diode lasers due to electron number fluctuations
Authors: Welford D. , Mooradian A.
Published: February 2003

We report here the experimental observation of power-independent linewidth broadening of cw single-frequency (GaAl)As diode lasers. This phenomenon is attributed to refractive index fluctuations resulting from statistical fluctuations in the number of conduction electrons in the small active volume of the devices studied.
Optically induced catastrophic degradation in InGaAsP/InP layers
Authors: Temkin H. , Mahajan S. , DiGiuseppe M. A. , Dentai A. G.
Published: February 2003

Laser-induced catastrophic degradation in InGaAsP layers has been investigated. Catastrophic dark line (CDL) defects are generated at the spontaneous radiation flux in excess of 100 MW/cm2, significantly higher than in similar GaAlAs structures. In contrast to CDL’s in GaAlAs these dark lines are shown to be due to localized melting at material defects and not at cleaved mirror facets. In view of the very high power threshold this type of catastrophic degradation should be of limited importance for the InGaAsP lasers.
A novel technique for GaInAsP/InP buried heterostructure laser fabrication
Authors: Liau Z. L. , Walpole J. N.
Published: February 2003

A simple fabrication technique for GaInAsP/InP buried heterostructure lasers has been developed based on a newly observed mass transport phenomenon on chemically etched InP mesas. Threshold currents as low as 9.0 mA have been obtained.
Surface composition and etching of III-V semiconductors in Cl2 ion beams
Authors: Barker R. A. , Mayer T. M. , Burton Randolph H.
Published: February 2003

Surface composition and etching of InP and GaAs in Cl2 ion beams was investigated. In situ analysis of the substrate using Auger electron spectroscopy demonstrated selective removal of phosphorous from InP leaving a thin (⩽50 Å) surface layer enriched with In after etching at room temperature with a 500-eV Cl+/Cl+2 beam. GaAs does not show selective removal of the group V element, resulting in no significant change in surface composition after etching. These results reflect the involatility of the In chlorides at room temperature. Etch rate results indicate that at low ion energy (200 eV) or high neutral reactant flux, removal of the group III chloride from the surface is rate limiting. At high ion energy (500 eV) and low neutral flux, supply of reactant to the surface is rate limiting.
Epitaxial NiSi2 formation by pulsed ion beam annealing
Authors: Chen L. J. , Hung L. S. , Mayer J. W. , Baglin J.E. E. , Neri J. M. , Hammer D. A.
Published: February 2003

Epitaxial nickel silicide layers have been formed by ion beam annealing of 300–400-Å Ni films on (001) Si with 300–400-ns pulses of H+ or Ba+ ions. Cellular structures were formed at an H+ energy density of 1.3 J/cm2 and a Ba+ energy density above about 0.7 J/cm2. At lower energy densities, uniform epitaxial layers of NiSi2 were formed, as indicated by both Rutherford backscattering channeling and transmission electron microscopy. With ion beam annealing, melting starts at the Ni/Si interface and epitaxy is found at energy densities well below that required to melt crystalline Si.
Oxidation-enhanced or retarded diffusion and the growth or shrinkage of oxidation-induced stacking faults in silicon
Authors: Tan T. Y. , Gösele U.
Published: February 2003

An analysis of the conditions for obtaining oxidation-enhanced or retarded dopant diffusions (OED or ORD), in accordance with the stacking fault growth/shrinkage phenomena, is carried out for the oxidation of Si by assuming that vacancy and Si self-interstitials coexist at high temperatures and that during oxidation a local equilibrium of point defects is attained. It is shown that the Sb ORD data can be explained quantitatively. Under most oxidation conditions the SiO2-Si interface acts as a source of Si self-interstitials, but at sufficiently high temperatures and long oxidation times the SiO2-Si interface behaves as a sink for Si self-interstitials (or equivalently as a source of vacancies). We suggest a model for this sink behavior in terms of the formation of SiO molecules at the interface and of their subsequent diffusion into the SiO2 film.
Laser-induced chemical vapor deposition of SiO2
Authors: Boyer P. K. , Roche G. A. , Ritchie W. H. , Collins G. J.
Published: February 2003

We have demonstrated rapid (3000 Å/min) photochemical deposition of silicon dioxide from gas phase donor molecules. An ArF (193 nm) laser was used to excite and dissociate gas phase SiH4 and N2O molecules in contrast to earlier work with incoherent mercury lamps. We have achieved 20 times the deposition rate, limited the dissociation volume to a localized region, and minimized the direct impingement of UV photons on the substrate. Although the SiO2 deposition rate was insensitive to substrate temperature from 20 to 600 °C, film quality noticeably improved above 200 °C. Metal-oxide-semiconductor capacitors were fabricated and characterized in order to measure SiO2 electrical properties. Film composition was investigated using Auger and infrared spectroscopy techniques and showed that the SiO2 is stoichiometric and contains less than 5% nitrogen.
n-CuInSe2/polysulfide photoelectrochemical solar cells
Authors: Mirovsky Yehudith , Cahen David
Published: February 2003

We report that n-type single crystals of n-CuInSe2 in aqueous polysulfide solution exhibit high quantum efficiencies of 0.8–0.9 in the wavelength region between 600–1150 nm when used as photoanodes in photoelectrochemical cells. Photocurrents of 28 mA/cm2 were measured on a ’’winter’’ day in Rehovot (71 mW/cm2) which corresponds to 40 mA/cm2 under AM1 (Air Mass 1) conditions (100-mW/cm2 sunlight). Stability tests of n-CuInSe2 photoanodes (20 000-C/cm2 photocharge passage) at short circuit current densities of 40 mA/cm2 have shown no deterioration whatsoever of the measured photocurrents.
Tunneling relaxation time measurements in thin oxide metal oxide semiconductor capacitors
Authors: Shimer J. A. , Dahlke W. E.
Published: February 2003

Photocapacitance of metal-oxide-semiconductor diodes with oxide thickness 20 Å<dox <40 Å was measured as function of photon energy and temperature to determine the relaxation time τT = τ0 exp(αdox) of metal electrons tunneling into interface states of the devices. We found an attempt-to-escape time τ0 = 10−5 s and a tunneling attenuation α = 0.5 Å−1 which increased about 10% from the silicon conduction band to midgap. Variations of the tunneling distance were Δdox = ±2.5 Å.
Logic delays of 5-μm current-switched Josephson gates
Authors: Pei S. S.
Published: February 2003

Logic delays of a current-switched latching gate called the Josephson atto-Weber switch and its use in a dc powered flip-flop module have been investigated. Experimental circuits with cascade chains of 31 gates were fabricated using 5-μm square lead alloy tunnel junctions. Delays were measured on both the latching and the unlatching chains. The experimental circuits demonstrate operation faster than those reported for other Josephson gate designs using the same linewidth. For the latching OR gate with fanout of 3, the shortest measured gate delay is 15 ps.
Resistor coupled Josephson logic
Authors: Sone J. , Yoshida T. , Abe H.
Published: February 2003

A resistor coupled Josephson logic (RCJL) family, composed of OR, AND, and 2/3 majority gates, is proposed. The RCJL family consists of multiple Josephson junctions and resistors, and employs current injected switching. OR gates have I-O isolation capability with high input sensitivity and wide operating current margin. In the AND gate, current margin as wide as the CIL AND gate and higher input sensitivity can be achieved without inductors. Experimental verification of the RCJL family operation is also described.
Picosecond measurement of spontaneous and stimulated emission from injection lasers
Authors: Duguay M. A. , Damen T. C.
Published: February 2003

Spontaneous and stimulated emission from gain-switched injection lasers is measured directly with picosecond resolution. Below threshold, the luminescence time profile shows a carrier concentration rise time of 300 ps in a transverse-junction AlGaAs laser diode. Above threshold, laser pulse widths down to 30 ps were observed and a regime of operation was found where a single longitudinal mode predominates in the output spectrum.
Reduction in crystallographic surface defects and strain in 0.2-μm-thick silicon-on-sapphire films by repetitive implantation and solid-phase epitaxy
Authors: Golecki I. , Glass H. L. , Kinoshita G.
Published: February 2003

A novel technique has been developed to reduce the high concentration of planar lattice defects and compressive strain throughout the thickness of chemically vapor deposited (CVD), epitaxial Si-on-sapphire (SOS) films. This technique involves two or more steps of Si implantation and furnace annealing below 600 °C. In each step, the most defective region of the Si film is amorphized and solid-phase epitaxial regrowth is induced using the least defective region as seed. Analyses using MeV 4He+ Rutherford backscattering/channeling and x-ray diffraction show that in a 0.16-μm-thick, (100) oriented, CVD SOS film which had been recrystallized in this way, the Si surface channeling yield was reduced from χ0 = 0.14 to 0.07 and the average in-plane strain decreased from ε∥ = −4.2×10−3 to −1×10−3.
X-ray photoemission spectroscopy study of surface oxidation of Nb/Al overlayer structures
Authors: Kwo J. , Wertheim G. K. , Gurvitch M. , Buchanan D. N. E.
Published: February 2003

We identify and characterize the chemical nature of the oxide formed by the air oxidation of thin Al overlayers on Nb. Take-off angle experiments were performed to determine the sequential layer configuration. The thickness of the oxide did not exceed 20 Å, regardless of the thickness of the metallic Al originally deposited. Grain-boundary diffusion is suggested as a mechanism for the removal of most of the excess metallic Al. The observation of a small amount of residual metallic Al near the interface is in accord with Miedema’s theory of surface segregation which indicates that Al will segregate to the surface of a Nb-Al alloy. An Al overlayer as thin as 9.5 Å is sufficient to protect the underlying Nb film from oxidation and to form an effective tunnel-junction barrier.
Enhancing micrographs obtained with a scanning acoustic microscope using false-color encoding
Authors: Hammer R. , Hollis R. L.
Published: February 2003

The periodic signal variations observed in reflection acoustic microscopy when lens-to-sample spacing is changed lead to reversals in image contrast. This contrast mechanism can be described by a V(Z) function, where V is the transducer voltage and Z the lens-to-sample spacing. In this work we show how by obtaining V(Z) curves from each plane of a complex sample, judicious choices of focal positions can be made to optimize signals from planes of interest, which allows color encoding of the image from each plane in an overlay image. We present false-color micrographs obtained in this way, along with A scans and V(Z) curves to demonstrate the technique.
InP electro-optic directional coupler
Authors: Carenco A. , Menigaux L. , Linh N. T.
Published: February 2003

An electro-optic directional coupler switch has been fabricated in InP with an homojunction structure. Each single-mode guide is made in a n layer grown on a n+ substrate, the p+ etched rib used to confine the light being obtained by diffusion. A linear variation of the coupling length with reciprocal wavelength has been found between 1.06 and 1.51 μm. By reversely biasing the ’’stepped Δβ’’ junctions with less than 12 V, both switching states have been achieved at 1.51 μm, with a power isolation better than 16 dB on a 8-mm-long device. This is a new promising step towards InP-integrated optics.
Growth of single-crystal CoSi2 on Si(111)
Authors: Tung R. T. , Bean J. C. , Gibson J. M. , Poate J. M. , Jacobson D. C.
Published: February 2003

Single-crystal CoSi2 films have been grown under ultrahigh vacuum conditions on Si (111) by both standard deposition and molecular beam epitaxy techniques. Films were analyzed by Rutherford backscattering spectroscopy and channeling, transmission electron microscopy, and low energy electron diffraction. The films are free of grain boundaries but are rotated 180° about the normal to the Si surface. The crystalline perfection, as measured by channeling, is the best yet reported for an epitaxial silicide system. The expected hexagonal misfit dislocation arrays, along with a coarser triangular defect structure, are confined to the plane of the interface.
Novel low-temperature recrystallization of amorphous silicon by high-energy ion beam
Authors: Nakata Jyoji , Kajiyama Kenji
Published: February 2003

An entirely new beam annealing method that employs a high-energy (∼2.5 MeV) heavy ion (As75, Kr84) beam is presented. With this technology, an amorphous Si layer is recrystallized at below ∼300 °C substrate temperature (much lower than the ordinary solid phase epitaxial growth temperature of ∼600 °C). The temperature just under the beam spot is estimated to be at most ∼20° C higher than that in the surrounding region, because of the large beam spot size (∼10 mmφ) and rapid scan speed (∼104 cm/s). This low-temperature annealing feature is quite different from the case for conventional furnace, laser, electron, and low-energy ion beam annealing. After recrystallization, impurity As atoms are located at substitutional sites with no tetrahedral interstitial components, and are scarcely redistributed.
Microscopy of Si films during laser melting
Authors: Lemons R. A. , Bösch M. A.
Published: February 2003

By using an optical microscope to directly observe thin Si films as they are melted with a cw argon laser beam, the crystallization process can be better understood. In an environment containing oxygen, stable filaments of solid silicon precipitate from the molten pool at low laser power. The surrounding melt may contain dissolved oxygen which reduces the melting point, allowing the liquid and solid to coexist. As laser power is increased a uniform molten pool is achieved. In emitted light the pool is dark compared to the surrounding solid due to the melt’s low emissivity. The spectrum of this emitted thermal radiation accurately fits the Planck law at 1740 °K, confirming the temperature of the melt.
Interface state generation in the Si-SiO2 system by photoinjecting electrons from an Al field plate
Authors: Pang Stella , Lyon S. A. , Johnson Walter C.
Published: February 2003

We observe the generation of interface states in the Si-SiO2 system when electrons are internally photoinjected from an Al field plate and are swept through the oxide by a moderate electric field. Interface states appear immediately at 90 K. The rate of interface state generation caused by photoinjected electrons depends on the oxide thickness and the magnitude of the bias field. The generated interface state density is found to increase as Nss = AQs, where Q is the injected charge and s is generally in the range 0.5–0.7. The generation does not saturate after passage of a total charge of 0.35 C/cm2.
Enhancement type InP metal-insulator-semiconductor field-effect transistor with plasma anodic aluminium oxide as the gate insulator
Authors: Hirayama Y. , Park H. M. , Koshiga F. , Sugano T.
Published: February 2003

Enhancement type InP metal-insulator-semiconductor field-effect transistors were fabricated using plasma anodic aluminium oxide as the gate insulator. The effective electron mobilities in the surface channel are 1250 cm2/Vs and 2000 cm2/Vs at 300 and 80 K, respectively. The drift of the drain current at 300 K ceases a few minutes after applying a gate voltage and stable dc operation is observed over several hours.
Mode selection and intensity enhancement of x rays in crystals
Authors: Chang Shih-Lin
Published: February 2003

Previously unreported intensity enhancement of x rays obtained by two-mode excitation is observed on the direct incident beam of synchrotron radiation. The excitation utilizes the coherent interaction of a six-beam Borrmann diffraction in a perfect silicon single crystal. The experiment provides a means of obtaining nearly divergenceless, monochromatic, spatially coherent, and intense x-ray sources for x-ray diffraction and imaging studies. Single mode excitation can be achieved by using a thick crystal.
Diffusion of arsenic in polycrystalline silicon
Authors: Swaminathan B. , Saraswat K. C. , Dutton R. W. , Kamins T. I.
Published: February 2003

The diffusion of arsenic in polycrystalline silicon films has been studied over the temperature range 750–950 °C and for grain sizes 210–510 nm. Rutherford backscattering spectrometry was used to measure the concentration profiles of arsenic, initially introduced into the polysilicon by ion implantation, after various annealing steps. The concentration profiles were found to be determined by a combination of two factors—the low diffusivity in the bulk of the rains and the much higher diffusivity in the grain boundaries. The diffusivity of arsenic in the grain boundaries was independent of concentration, with an activation energy of 3.9 eV, very close to that of the low-concentration arsenic diffusivity in single-crystal silicon. However, the value of the diffusivity was 8.6×104 exp(−3.9/kT)cm2/s, four orders of magnitude higher than the single-crystal value. The diffusivity in the interior of the grains was the same as that in single-crystal silicon.
Photodeposition of Zn, Se, and ZnSe thin films
Authors: Johnson W. E. , Schlie L. A.
Published: February 2003

Thin films of zinc, selenium, and zinc-selenide (nonstoichiometric) have been deposited at room temperature on various substrates by the photodissociation of zinc dimethyl and selenium dimethyl with an incoherent light source. Large thicknesses (∼6000Å) and areas with 2-cm cross diameters have been produced. This low-temperature technique may provide a drastically improved method for depositing laser mirror thin films that have much higher quality and purity levels not heretofore available by the more conventional methods such as vacuum deposition, electron or ion beams.
Low noise GaAs metal-semiconductor field-effect transistor made by ion implantation
Authors: Feng M. , Eu V. K. , Kanber H. , Watkins E. , Schellenberg J. M. , Yamasaki H.
Published: February 2003

Low noise GaAs metal-semiconductor field-effect transitors (MESFET’s) have been made by direct ion implantation into high pressure liquid encapsulated Czochralski (HPLEC) undoped substrates and unintentionally doped high resistivity buffer layers. A noise figure of 1.3 dB with 10.3-dB associated gain has been achieved at 12 GHz, and a 2.2-dB noise figure with 7.4-dB associated gain has been measured at 18 GHz with a 0.6-μm gate length by 300-μm gate width FET device, fabricated from a HPLEC undoped substrate. Comparable dc and rf performance has also been achieved for devices fabricated from undoped buffer layers. Equivalent circuit elements have been evaluated in an effort to understand the critical parameters necessary to achieve these results.
Ar+ laser induced chemical vapor deposition of Si from SiH4
Authors: Bäuerle D. , Irsigler P. , Leyendecker G. , Noll H. , Wagner D.
Published: February 2003

For the first time polycrystalline silicon has been grown by using the visible light of an Ar+ laser for pyrolytical decomposition of SiH4. With a laser irradiance of 3600 W/mm2 a deposition rate of 30 μm/s was obtained. The temperature dependence of the deposition rate was investigated. The kinetically controlled regime is characterized by an activation energy of 44±4 kcal/mole.
Absorption measurements at high pressure on AlAs-AlxGa1−xAs-GaAs superlattices
Authors: Kirchoefer S. W. , Holonyak N. , Hess K. , Gulino D. A. , Drickamer H. G. , Coleman J. J. , Dapkus P. D.
Published: February 2003

Absorption data (300 K) are presented on AlxGa1−xAs-GaAs and AlAs-GaAs superlattices subjected to hydrostatic pressure (0–10 kbar). These data show that the confined-particle transitions, which partition and ’’label’’ the Γ energy band high above the band edge (as high as 400 meV or well above the L minima), all move with the same pressure coefficient (11.5 meV/kbar). A weaker effect of the L than the X indirect minima on the absorption is observed.
Transmission of CO2 laser power by single-crystal CsBr fibers
Authors: Mimura Y. , Ota C.
Published: February 2003

Transmission of a CO2 laser beam by single-crystal CsBr fibers with losses of 0.3∼0.4 dB/m has been investigated. Transmission losses including the fiber losses and joint losses were less than 30% per meter. Using a 55-W CO2 laser as a source power, a 47-W continuous laser beam has been transmitted through 1-mm-diam fiber without any degradation of the fiber.
Raman spectra from Ga1−xInxAs epitaxial layers grown on GaAs and InP substrates
Authors: Kakimoto K. , Katoda T.
Published: February 2003

Raman spectra from Ga1−xInxAs epitaxial layers of various compositions were studied. Both disorder-activated acoustic and optical phonons appeared in the midrange of composition independent of substrate materials. Broadening in the LO phonon due to stress was also observed near the interface region between the epitaxial layer and the substrate when there was lattice mismatch between them even if the amount was as small as 0.7%.
A closely spaced (50 μm) array of 16 individually addressable buried heterostructure GaAs lasers
Authors: van der Ziel J. P. , Logan R. A. , Mikulyak R. M.
Published: February 2003

An array of 16 individual addressable lasers with 50-μm center spacing has been monolithically integrated on a GaAs chip and cw bonded to a Si submount and copper heat sink. The lasers have the loss stabilized buried heterostructure geometry with separate optical and carrier confinement. The advantages of this laser geometry for integration into arrays are described.
Optical pulse compression based on enhanced frequency chirping
Authors: Grischkowsky D. , Balant A. C.
Published: February 2003

Through numerical simulations, we show that, under relatively general conditions, passage of an intense picosecond pulse through a single-mode optical fiber can cause the pulse to become strongly frequency broadened with a positive chirp (linear frequency sweep) describing essentially all of the energy of the output pulse. Also, because the optical fiber supports only a single transverse mode, the entire output beam profile has the same frequency modulation. These two features allow for unprecedented optical pulse compression.
Derivative-free inversion of Abel’s integral equation
Authors: Deutsch Moshe , Beniaminy Israel
Published: February 2003

We present a new inversion formula for Abel’s integral equation which does not require derivatives of any of the functions involved. This is a particularly desirable feature when analyzing experimentally derived data, since differentiation enormously amplifies the random errors inherent in all measured data. The high quality of the results obtainable using the new formula is demonstrated by a typical numerical example for which it yields errors smaller by an order of magnitude than those obtained with the usual inversion formula.
Field imperfection induced frequency shifts in a Penning trap
Authors: O Chun-Sing , Gärtner G. F. , Schuessler H. A.
Published: February 2003

The effects of field imperfections on the cyclotron resonance frequency of charged particles stored in imperfect Penning traps were evaluated. Anharmonicity in the electric potential distribution and the magnetic field misalignment lead to shifted and asymmetrically broadened resonance signals. The frequency shifts were observed experimentally. The corrected cyclotron resonance frequencies are in good agreement with the cyclotron frequency obtained through extrapolation to zero confining voltage.
The effect of baking and pulsed laser irradiation on the bulk laser damage threshold of potassium dihydrogen phosphate crystals
Authors: Swain J. E. , Stokowski S. E. , Milam D. , Kennedy Gretchen C.
Published: February 2003

We increased the bulk laser damage threshold of potassium dihydrogen phosphate crystals by as much as a factor of 5 by first baking the crystals at 140 °C for 24 h and then irradiating them with laser pulses of increasing fluence. The combination of baking and subthreshold laser irradiation was more effective in improving bulk damage thresholds than either process alone. The combined process was effective for all laser pulse durations from 1 to 20 ns.
Formation kinetics of MoSi2 induced by cw scanned laser beam
Authors: Bomchil G. , Bensahel D. , Golanski A. , Ferrieu F. , Auvert G. , Perio A. , Pfister J. C.
Published: February 2003

Scanned cw laser beams at different scan velocities from 10 to 400 cm/s have been used to study the interaction of thin metal films of molybdenum deposited by electron beam evaporation with single-crystal silicon substrate. Backscattering technique has been used to investigate the growth mechanism of hexagonal silicide MoSi2 as a function of the number of repetitive laser scans. Silicide layers are found to grow at a rate proportional to the square root of the effective annealing time in the whole range of scan velocities. Effective annealing temperatures are calculated for each laser annealing condition, and from an Arrhenius plot a mean value of activation energy for MoSi2 growth is estimated.
Semihydrodynamic model for ion separation in a fast pinch
Authors: Barak G. , Rostoker N.
Published: February 2003

It has been found experimentally that if a mixture of hydrogen and argon is pinched, a separation between the two components occurs very early during the implosion phase; the light ions move faster to the center, leaving the heavier ions behind. A model is presented which describes the dynamics of the pinch and explains the separation. The collisional electron gas is treated as a fluid and the ions are treated as free particles accelerated by the collective electrostatic field set up by the flow. The set of equations describing such a flow is presented and some simple problems are worked out in order to show that a separation is possible. These problems include the ion sound wave, the general flow with impurities, and the shock wave structure.
Fracto-emission from pentaerythritol tetranitrate and cyclotetramethylene tetranitramine single crystals
Authors: Miles M. H. , Dickinson J. T.
Published: February 2003

Single crystals of the explosives pentaerythritol tetranitrate (PETN) and cyclotetramethylene tetranitramine (HMX) were fractured in vacuum while viewed by particle detectors strongly biased on separate positive and negative charge. Particles were detected on both detectors during and following fracture. Previous results on polymers suggest we are detecting electrons and positive ions. The observation of fracto-emission from these molecular crystals implies that crack propagation in such materials can break intramolecular bonds and the subsequent chemical reactions that lead to particle emission can continue for several minutes on the freshly created fracture surfaces.
Subsurface-structure determination using photothermal laser-beam deflection
Authors: Wetsel Grover C. , McDonald F. Alan
Published: February 2003

Photothermal imaging using laser-beam deflection is shown to be a successful means of detecting subsurface structure in solids. Experimental data for known and unknown subsurface structures are reported. The existing theory agrees well with data on broad subsurface structures, but small subsurface structures produce signal variations which are better represented by a subsurface thermal contact resistance. The first photothermal-image characterization of a microscopic, unknown subsurface defect is presented.
Four-coefficient weak-field magnetoresistance measurements on (111)-oriented epitaxial n-type PbTe films at 4.2 K
Authors: Allgaier R. S. , Abbundi R. J. , Houston Bland , Davis J. L. , Martinez A. , Restorff J. B.
Published: February 2003

A recently developed four-coefficient weak-field magnetoresistance measurement technique was applied to (111)-oriented n-type PbTe films at 300, 77, and 4.2 K. In three out of four films studied, the results at 4.2 K exhibit unique characteristics—an essentially zero longitudinal magnetoresistance and hexagonal electronic symmetry—which indicate that all carriers have been transferred to one ellipsoid-of-revolution valley of the multivalley PbTe conduction band. This transfer results from substrate-induced strain, and it leads to conductivity anisotropies (σ∥/σ⊥) from 6 to 16. The large sample-to-sample scatter in this ratio is tenatively ascribed to a strain which varies across the film thickness. Random inhomogeneities cannot account for the scatter, since they would eliminate the zero longitudinal magnetoresistance found in all three samples.
Channeling photodiode: A new versatile interdigitated p-n junction photodetector
Authors: Capasso F. , Logan R. A. , Tsang W. T. , Hayes J. R.
Published: February 2003

We report on the operation of the first channeling photodetector. This device can be operated as an ultrahigh sensitivity photocapacitive detector; large capacitance variations (≂1 pF) have been induced by very low power levels (≂20 pW). In addition this structure may be used as a low punch through voltage pin photodiode with an ultralow capacitance (≂0.06 pF) largely independent of the detector area and of the doping level of the layers. Finally this device represents the first step towards the implementation of the recently disclosed low noise avalanche photodiode with separated electron and hole avalanche regions.
Narrow stripe AlGaAs lasers using double current confinement
Authors: Blauvelt H. , Margalit S. , Yariv A.
Published: February 2003

Gain guided AlGaAs lasers in which the current is restricted to flow between two narrow stripes have been fabricated. The double current confinement configuration, which is fabricated by a selective meltback-growth technique, enables the current injection to be restricted to a very narrow section of the active layer. These lasers exhibit very strong antiguiding and operate in many longitudinal modes, which are characteristics of narrow stripe lasers. Potential applications of the twin vertical stripe configuration include arrays of optically coupled lasers and, if a real index waveguiding mechanism can be combined with double current confinement, low threshold lasers.
Nonlinear optics of long range surface plasmons
Authors: Stegeman G. I. , Burke J. J. , Hall D. G.
Published: February 2003

We analyze codirectional and counterpropagating second harmonic generation, degenerate four-wave mixing, and intensity-dependent refractive index phenomena based on surface plasmon polaritons guided by thin metal films. Promising cross sections are predicted for three out of the four cases.
Rapid isothermal anneal of 75As implanted silicon
Authors: Wilson S. R. , Gregory R. B. , Paulson W. M. , Hamdi A. H. , McDaniel F. D.
Published: February 2003

Silicon wafers implanted with 75As have been annealed with a Varian IA-200 isothermal annealer. The anneal occurs in vacuum using radiation from a resistively heated sheet of graphite. The anneal quality depends on the graphite heater temperature and exposure time. If the anneal time is too short implantation damage remains and if the time is too long measurable losses of As occur causing the sheet resistance to increase. The loss of As can be prevented by depositing 0.05 μm of SiO2 on the wafer before annealing.
Band-gap enhanced carrier heating in InGaAsP/InP double heterostructure light-emitting diodes
Authors: Wada Osamu , Yamakoshi Shigenobu , Sakurai Teruo
Published: February 2003

Carrier (electron) temperature in InGaAsP/InP double heterostructure light-emitting diodes (LED’s) was analyzed in detail over a wide band-gap range corresponding to the wavelength range of 1.15–1.5 μm. The carrier temperature was shown to be uniquely determined by the injected carrier density at each wavelength. It was found, however, that the rise of the carrier temperature above the lattice temperature at the 1.5-μm wavelength to be approximately three times larger, compared at the same injection level, than that observed below 1.3 μm. This is related to the enhanced LED current-power sublinearity at 1.5 μm. An inefficient carrier cooling at this quaternary composition was suggested as a major cause for this distinct band-gap dependence.
Ga0.80In0.20As 1.20-eV high quantum efficiency junction for multijunction solar cells
Authors: Dietze W. T. , Ludowise M. J. , Gregory P. E.
Published: February 2003

A Ga0.80In0.20As junction for solar cell applications grown on GaAs by organometallic vapor phase epitaxy (OMVPE) with a peak collection quantum efficiency of 92% is reported. This junction is fabricated using step-graded layers to reduce misfit dislocations between the junction and the substrate. The effects of step grading on the projected short circuit current density, peak quantum efficiency, and diode ideality factor have been measured. With grading, the ideality factor is reduced from n=2.7 to 1.2 for current densities greater than 0.01 A/cm2. This high-performance Ga0.80In0.20As can serve as an excellent low-gap junction for multijunction solar cells.
Scanning transmission electron microscope microanalytical study of phosphorus segregation at grain boundaries in thin-film silicon
Authors: Rose J. H. , Gronsky R.
Published: February 2003

Phosphorus segregation at grain boundaries in thin-film silicon has been investigated by scanning transmission electron microscope x-ray microanalysis. Low-pressure chemically vapor-deposited silicon was heavily diffusion doped and subsequently annealed at 650, 700, 750, or 800 °C. Enhanced phosphorus concentrations were observed at grain boundaries with increasing levels at lower annealing temperatures. The amount of segregation was also found to vary from boundary to boundary in each specimen. The average energy of segregation was evaluated as 7.5 kcal/mol.
Effect of strain on the critical current and critical field of B1 structure NbN superconductors
Authors: Ekin J. W. , Gavaler J. R. , Gregg J.
Published: February 2003

The effect of uniaxial strain on the critical current of NbN superconductors has been measured at 4.2 K in magnetic fields from 6 to 22 T. Unlike A15 superconductors, the critical current of B1 structure NbN shows no measurable dependence on elastic strain, even at fields as high as 22 T. Furthermore, the bulk upper critical field determined from the high-field critical current data is independent of uniaxial strain within experimental error (±0.5%). The irreversible strain limit εirrev where the superconductor is permanently damaged was measured to be greater than 0.7% (0.5% intrinsic strain) in 0.2-μm-thick film samples. Values of εirrev were observed to correlate with the microstructure of the NbN films as well as with the onset of substrate yielding.
Field induced tunneling in Hg1−xCdxTe photodiodes
Authors: Anderson W. W.
Published: February 2003

Using insulated field plates, we have observed band-to-band tunneling and impurity-to-band tunneling in ion-implanted n+-on-p Hg1−xCdxTe photodiodes. The latter process results in a field-plate-voltage controlled negative resistance region in the forward biased I-V characteristic. The peak and valley voltages for this excess current process are greater than those observed in Esaki type tunnel diodes.
1.3-μm wavelength GaInAsP/InP double heterostructure lasers grown by molecular beam epitaxy
Authors: Tsang W. T. , Reinhart F. K. , Ditzenberger J. A.
Published: February 2003

We report the first successful preparation of current injection GaInAsP/InP double heterostructure lasers operating at 1.3 μm by molecular beam epitaxy. The median threshold current density Jth is 3.5 kA/cm2, while the lowest Jth is 1.8 kA/cm2 for broad-area Fabry–Perot diodes of 380×200 μm and an active layer thickness of 0.2 μm. The threshold current-temperature dependence is described very closely by exp (T/T0) with T0 of 70–87 K in the temperature range 10°–65 °C. Elemental As and P (red phosphorus) were used as the primary molecular beam sources for deriving the As2 and P2 beams. In addition, the As and P ovens were equipped with recharge interlock systems. As a result, the growth chamber was always maintained in ultrahigh vacuum condition even during As and P recharge.
Irradiation-induced phase transformation in type 304 stainless steel
Authors: Hayashi N. , Takahashi T.
Published: February 2003

Conversion electron Mössbauer spectroscopy has been used to study irradiation effects in the near surface region of type 304 stainless steel after 40 keV helium ion bombardment; a ferromagnetic phase in the paramagnetic matrix was observed after the irradiation to 8×1017 ion/cm2 at 200 °C. The amount of ferromagnetic phase was found to increase with increasing helium ion fluence.
Frequency locking of an InGaAsP semiconductor laser to the first overtone vibration-rotation lines of hydrogen fluoride
Authors: Yamaguchi Shizuo , Suzuki Masao
Published: February 2003

The first overtone vibration-rotation lines of hydrogen fluoride have been observed around the wavelength region of 1.3 μm by using a current-tunable InGaAsP semiconductor laser operated at the temperature range from −24 °C to +24 °C. The laser frequency has been locked to one of the R-branch lines with the stability of 2.0×10−10≥σ(2,τ)≥7.9×10−11 at the averaging time between 1 and 240 s.
Correlation between the piezoelectric constant d31 and b-axis distribution in polyvinylidene fluoride
Authors: McBrierty V. J. , Douglass D. C. , Wang T. T.
Published: February 2003

Nuclear magnetic resonance linewidths are analyzed to provide information on dipole distributions in β-polyvinylidene fluoride as a function of poling time in order to establish the contribution of the dipole reorientation mechanism to the time evolution of the piezoelectric d31 constant. Results indicate that dipole reorientation proceeds continuously with time and is not uniquely associated with the initially rapid and subsequently slower evolution of d31 with time. It is observed that d31 correlates well with 〈cos 2δ〉, where δ is the angle between a typical b axis and the poling direction. The magnitude of 〈cos 2δ〉 and 〈4δ〉 which characterize the remanent polarization indicates that dipole alignment is far from perfect along the poling direction even in the most strongly poled material.
Theory of optical mixing by mobile carriers in superlattices
Authors: Bloss W. L. , Friedman L.
Published: February 2003

The third order nonlinear susceptibility χ(3) caused by band nonparabolicity is investigated for gallium arsenide-gallium aluminum arsenide superlattices. Optimization of well width, superlattice periodicity, and barrier height give rise to large nonparabolicities which produce nonlinear susceptibilities comparable to those found in indium antimonide and at least two orders of magnitude larger than bulk gallium arsenide.
Anomalous diffusion behavior of Mg in GaAs
Authors: Small M. B. , Potemski R. M. , Reuter W. , Ghez R.
Published: February 2003

This experiment was undertaken to demonstrate that the anomalous diffusion behavior reported of Al in the alloy system (AlGa)As is not unique. The interdiffusion of Al and Ga across the buried heterojunctions between the AlAs and GaAs layers of a superlattice structure has been shown to be slow, whereas very much faster diffusion has been observed into the free surface of a GaAs wafer exposed to a saturated solution containing these two elements and Al. In this letter it is shown that Mg exhibits similar behavior and, further, a consequence is that when Mg is used to dope GaAs layers grown by liquid phase epitaxy the dopant penetrates to a significant depth in the underlying solid.
CO2 laser-induced melting of indium antimonide
Authors: Hasselbeck M. , Kwok H. S.
Published: February 2003

Using picosecond CO2 laser pulses, the following sequence of events was identified in high power laser-semiconductor interaction: (i) generation of a dense (≳1018 cm3) plasma, (ii) melting of the crystal by free-carrier absorption, (iii) formation of surface ripples at the breakdown threshold, and (iv) formation of a crater at higher intensities. The melting without breakdown region can be quite broad and may have potential applications in semiconductor processing and annealing.
Thermal annealing behavior of an oxide layer under silicon
Authors: Hamdi A. H. , McDaniel F. D. , Pinizzotto R. F. , Matteson S. , Lam H. W. , Malhi S. D. S.
Published: February 2003

High resolution Rutherford backscattering spectrometry and ion channeling have been employed to evaluate the crystallinity of the surface silicon layer in oxygen implanted silicon. The quality of the top surface layer was determined by measuring the minimum yields along 〈110〉 directions in channeling spectra. Single crystal (100) silicon was implanted with 300 keV O+2 to a dose of 1.06×1018 O+2 /cm2. Measurements of residual damage of the top layer were made after annealing the samples at 1150 °C for times ranging from 10 to 240 min in either Ar or N2. Under the implantation conditions used in this experiment, a uniform oxide layer 0.52 μm thick was buried under a top silicon layer 0.17 μm thick. The buried oxide layer has abrupt silicon to oxide interfaces. The highest quality silicon surface layer was produced after 3-h annealing in an Ar ambient. A lesser quality silicon surface layer was produced by annealing for shorter times or for equivalent times in N2 ambient.
Transmission electron microscopy of GaAs grown over submicrometer-period tungsten gratings
Authors: Vojak B. A. , Salerno J. P.
Published: February 2003

The GaAs overgrowth of tungsten gratings, the most critical step in the fabrication of the permeable base transistor (PBT), has been characterized by transmission electron microscopy (TEM). The 3200-Å-period tungsten base gratings for the PBT are very uniform in linewidth and spacing before the GaAs overgrowth, and this uniformity is preserved after the overgrowth. Both voids and stacking faults are observed in the epitaxial GaAs grown over the gratings. An unexpected result of this study is the observation that a considerable density of such defects can be present in a PBT wafer that yields uniform, high-frequency devices.
Catastrophic degradation level of visible and infrared GaAlAs lasers
Authors: Wakao Kiyohide , Takagi Nobuyuki , Shima Katsuhito , Hanamitsu Kiyoshi , Hori Ken-ichi , Takusagawa Masahito
Published: February 2003

Burn-off output powers of catastrophic failures have been studied for GaAlAs double heterostructure (DH) lasers with facet coatings in the wavelength range of 750–870 nm. It was found that the burn-off power density does not depend on the lasing wavelength when the laser is operated under pulsed condition, whereas it decreases slightly as the wavelength becomes shorter under cw condition.
Real-time phase conjugate window for one-way optical field imaging through a distortion
Authors: Fischer Baruch , Cronin-Golomb Mark , White Jeffrey O. , Yariv Amnon
Published: February 2003

We demonstrate one-way optical field imaging through a distorting medium using a four-wave mixing implementation of real-time holography. Information can be transmitted at an arbitrarily fast rate as long as the mixing medium can respond to changes in the distortion.
Ion beam epitaxy of silicon on Ge and Si at temperatures of 400 K
Authors: Zalm P. C. , Beckers L. J.
Published: February 2003

Epitaxial growth of silicon on Ge (100), Si (100) and Si (111) wafers at substrate temperatures close to 400 K was observed in ion beam deposition experiments under UHV conditions (10−7 Pa). Single-charged Si+ beams of about 5-10 μA at an acceleration energy of 50 eV and a 5-mm-diam spot size were employed. Purity and crystallinity of the layers formed were checked by Auger electron spectroscopy (AES) and Rutherford high energy electron diffraction (RHEED).