bluuebunny/crossref_metadata_2025 huggingface dataset:
Carrier lifetime controlled by capture into deep and shallow centers in GaAs
Authors: Bludau W. , Wagner E.
Published: February 2003

Impact ionization of shallow centers in n-GaAs is utilized to control the branching ratio of the two carrier-recombination channels via shallow centers and via acceptors. We report the first purely optical measurements for the rate of electron capture into an acceptor. This rate is too small to significantly affect, in general, the lifetimes of free excess majority carriers in GaAs at low temperatures; the carrier lifetime is not determined by nonradiative recombination via centers near the middle of the band gap.
Depletion-mode GaAs MOS FET
Authors: Lile D. L. , Clawson A. R. , Collins D. A.
Published: February 2003

GaAs MOS field-effect-transistors (FET’s) have been fabricated by the anodic oxidation of liquid-phase epitaxial layers of GaAs grown on semi-insulating substrates. This letter reports on the characteristics of these devices operating in the depletion mode.
Energy reflection from gold bombarded with keV protons at various angles of incidence
Authors: So/rensen H.
Published: February 2003

The calorimetric deuterium film method operating at liquid-helium temperature was used for measuring the energy reflection coefficient γ for 1–10-keV protons incident on gold at angles of incidence up to 75°. H+2 and H+3 ions were used to obtain the lowest velocities. The growth with angle increases with energy. There is fair agreement with the theoretical results of Robinson and of Oen and Robinson.
p-n photoelectrolysis cells
Authors: Nozik A. J.
Published: February 2003

The efficiency of photoelectrolysis with solar radiation can be greatly enhanced by using simultaneously illuminated n- and p-type electrodes. An energy level scheme for heterotype and homotype p-n photoelectrolysis cells is presented which explains the enhanced efficiency. Data are presented for the homotype n-GaP/p-GaP and the heterotype n-TiO2/p-GaP systems which support the energy model. H2 and O2 are produced in the n-TiO2/p-GaP cell without the need of an external anodic bias.
High-quantum-efficiency photoemission from an InGaAsP photocathode
Authors: Escher J. S. , Antypas G. A. , Edgecumbe J.
Published: February 2003

An improved InGaAsP quaternary III-V material has been developed for near-ir photocathode applications. A quantum efficiency of 9.0% per incident photon at 1.06 μm from a 1.15-eV band-gap sample has been achieved at room temperature.
Pulsed room-temperature operation of In1−xGaxP1−zAsz double heterojunction lasers at high energy (6470 Å, 1.916 eV)
Authors: Coleman J. J. , Holonyak N. , Ludowise M. J. , Wright P. D. , Chin R. , Groves W. O. , Keune D. L.
Published: February 2003

Pulsed room-temperature operation of LPE In1−xGaxP1−zAsz double heterojunction (DH) laser diodes at short wavelength is described (Jth≲2×104 A/cm2, λ∼6470 Å, heterobarrier ΔE∼137 meV). The differential quantum efficiency of these diodes is ηext∼5%, and is considered to be low because of large diode size, thick active region, probably some layer mismatch and growth defects, and relatively poor heat sinking. The temperature dependence of threshold current density (Jth∼J0 expT/T0, T0∼74 °K) is presented in the range 77–300 °K and is compared with similar diodes having smaller heterobarriers and which, as expected, exhibit poorer performance (smaller T0).
Low-threshold cw Raman laser
Authors: Hill K. O. , Kawasaki B. S. , Johnson D. C.
Published: February 2003

Continuous-wave Raman oscillation has been obtained employing single-mode glass fibers in a Fabry-Perot resonator configuration. The pump-power input to the Raman laser required to reach threshold is 5 W of which approximately 50% is coupled into the fiber. The dominant oscillation of the Raman laser is at 499.1 nm with a 488.0-nm pump source.
Measuring pulsed picometer-displacement vibrations by optical interferometry
Authors: Vilkomerson David
Published: February 2003

Optical interferometers are very sensitive if they operate at the point halfway between the peak and minimum of detected intensity. By introducing a 90° phase shift between orthogonal polarizations in the reference beam, the interferometer signals due to each polarization are in quadrature; squaring and summing the signals effectively stabilizes the operating point of the interferometer at the high-sensitivity point, independent of the large low-frequency variations in optical-path difference caused by ambient disturbances. This method has been used to make stable (±0.5 dB) measurements of 2.5-MHz ultrasound pulses of 1-pm displacement.
Nuclear-pumped 3He-Ar laser excited by the 3He(n,p)3H reaction
Authors: Jalufka N. W. , DeYoung R. J. , Hohl F. , Williams M. D.
Published: February 2003

A volumetric direct nuclear-pumped laser has been achieved for the first time by using the 3He(n,p)3H reaction to excite a 3He-Ar laser. Lasing was achieved at 1.79 μ in Ar I at total pressures ranging from 200 to 700 Torr with 10% Ar, demonstrating stable high-pressure lasing. Laser energy output increased with both increasing total pressure and thermal neutron flux.
Reflective holograms on thermoplastic-photoconductor media
Authors: Lee T. C.
Published: February 2003

It is possible to record holograms on a thermoplastic-photoconductor medium coated over a reflective substrate. Both analysis and experiment will be presented. The analysis shows that during recording only the interference term responsible for the formation of the primary image generates significant electrostatic fringes while other interference terms contribute insignificantly to electrostatic fringe formation. In the reflective readout mode, two reconstructed images are superimposed to give a three- to fourfold increase in the diffraction efficiency.
Gas breakdown at cyclotron resonance with a submillimeter laser
Authors: Hacker M. P. , Temkin R. J. , Lax B.
Published: February 2003

A pulsed 496-μm CH3F laser is used to produce gas breakdown in He at pressures between 1 and 300 Torr in an intense longitudinal magnetic field. Breakdown is detected by the observation of visible light when the electron cyclotron frequency (eB/m) equals the laser frequency, which occurs at B=216 kG for λ=496 μm. At the lowest helium pressures and near cyclotron resonance, the focused laser intensity of 40 kW/cm2 gives rise to very large electron heating rates, well beyond the limit of validity of conventional equilibrium breakdown theory. The observed result is an intensity-dependent resonant linewidth, much larger than predicted by equilibrium theories.
Optical frequency conversion processes in atomic Rydberg states
Authors: Lau A. M. F. , Bischel W. K. , Rhodes C. K. , Hill R. M.
Published: February 2003

We present an analysis of optically pumping Rydberg states in alkalis to generate coherent lasers in the infrared and far-infrared spectral regions. Based on the previous accurate experimental and theoretical data on these states, our conclusion is that such laser systems can be operated either pulsed or cw and possess narrow linewidths, high gains, and considerable tunability. Wavelengths near 16, 12, 8.6, and 7.7 μm which are of interest for isotope separation are achievable with milliwatt power levels. Specific examples for Na vapor are given.
Stability of multiatmosphere H2-F2-O2 mixtures for HF laser studies
Authors: Truby Frank K.
Published: February 2003

Explosion pressures for multiatmosphere mixtures of H2, F2, and O2 have been obtained. Mixtures exhibiting short-term stability have been prepared with total pressures up to 11 atm.
Experimental demonstration of high-power fast-rise-time switching in silicon junction semiconductors
Authors: Zucker O. S. F. , Long J. R. , Smith V. L. , Page D. J. , Hower P. L.
Published: February 2003

Experimental results are presented demonstrating fast turn-on and high power-handling capability in light-activated silicon junction (PNPN) devices. Rise time to 2 ns, rate of current rise to 760 kA/μs, and switched power level of 10 MW were demonstrated.
Thermal reaction of Ti evaporated on GaAs
Authors: Wada O. , Yanagisawa S. , Takanashi H.
Published: February 2003

The thermal reaction of a vacuum-evaporated Ti film with substrate GaAs has been investigated using Auger electron spectroscopy and x-ray diffractometry. As accumulation and Ga depletion at the Ti/GaAs interface and Ga pileup in front of the As-rich layer have been observed. The As-rich and the Ga-rich layers have been found to be composed of TiAs/Ti5As3 and Ti2Ga3/Ti5Ga4, respectively. It has also been found that the rate of the Ti-GaAs reaction is governed by the interdiffusion process of Ti and As at the interface with an activation energy of 1.70±0.05 eV. The low diffusivity and relatively high Schottky barrier height of the present system facilitate the formation of useful Schottky barrier junctions.
EPR evidence for a positively charged vacancy-oxygen defect in silicon
Authors: Brosious Paul R.
Published: February 2003

A new EPR spectrum, labeled Si-I3, has been observed in electron-irradiated n-type Czochralski silicon illuminated with approximately band-gap light. The g-tensor symmetry, the g shifts from the free-electron value, and the temperature dependence of the spectrum amplitude lead to the conclusion that the spectrum originates from a positively charged vacancy-oxygen defect.
Bulk-hardened Sm-Co-Cu-Fe 2:17 magnets
Authors: Menth A. , Nagel H.
Published: February 2003

Sm(C00.87Cu0.13)z alloys were prepared with 7.2⩽z<8. Homogenization heat treatment yielded single-phase 2:17 material for z≳7.2. For z=7.8 some of the Co was substituted by Fe. Homogenized alloys remained single phase for up to 15% Co substituted. Remanence values BR up to 12.1 kG were reached. Coercive fields IHC of 4 kOe were achieved by means of a low-temperature heat treatment. The magnetization process implies that pinning of the Bloch walls is responsible for the coercivity mechanism.
Coexistence of two charge density waves of different symmetry in transition metal dichalcogenide 4H
b-TaS2
Authors: Narayan J.
Published: February 2003

Electron diffraction studies of 4Hb-TaS2 have shown that layers with octahedral (OC) and trigonal prismatic (TP) coordination undergo independent transitions to charge density wave states similar to those in 1T-TaS2 (pure OC) and 2H-TaS2 (pure TP), respectively. This is in agreement with the transitions observed in physical properties such as the electrical resistivity, magnetic susceptibility, and heat capacity for this material.
Ion acceleration schemes employing a slow space-charge wave
Authors: Yadavalli S. V.
Published: February 2003

Four different ion acceleration schemes that employ a slow space-charge wave on an electron beam are suggested and discussed. Also, some of the basic characteristics of such schemes are pointed out.
Direct detection of the parametrically generated half-harmonic voltage in a Josephson tunnel junction
Authors: Mygind J. , Pedersen N. F. , Soerensen O. H.
Published: February 2003

The first direct observation of the parametrically generated half-harmonic voltage in a Josephson tunnel junction is reported. A microwave signal at f=17.25 GHz is applied to the junction dc current biased at zero voltage such that the Josephson plasma resonance fp=f/2. Under these conditions a large-amplitude microwave signal is emitted at fp provided the input power exceeds a threshold value. The results are compared to existing theory.
Performance of multifilamentary Nb3Sn under mechanical load
Authors: Easton D. S. , Schwall R. E.
Published: February 2003

The critical current of a commercial multifilamentary Nb3Sn conductor has been measured under the application of uniaxial tension at 4.2 K and following bending at room temperature. Significant reductions in Jc are observed under uniaxial loading. Results are presented for a monolithic conductor manufactured by the bronze diffusion technique and for cable conductors formed by the tin-dip technique.
Parametric resonance of systems with time-varying dissipation
Authors: Batchelor D. B.
Published: February 2003

A prototype of a system with periodically time-varying dissipation is analyzed. It is found that parametric excitation can occur even if the average dissipation is positive, although it is necessary that the dissipation be negative (amplification) over part of the cycle. The pump amplitude threshold and unstable phase angle are found for the unstable region near ω1=2ω0. It is also shown that a periodic instability cannot be dynamically stabilized by periodically varying the dissipation.
Single-crystal Sr2Nb2O7 film optical waveguide deposited by rf sputtering
Authors: Ishitani Akihiko , Kimura Masakazu
Published: February 2003

A new optical waveguide of a single-crystal Sr2Nb2O7 film grown onto a b-plate Sr2Ta2O7 substrate by rf sputtering is reported. Waveguide propagation loss was 7.6 dB/cm for the TE0 mode at 6328 Å. An increased oxygen concentration in the sputtering gas is effective in lowering the optical waveguide propagation loss.
Miniaturized cw LiNdP4O12 laser pumped with a semiconductor laser
Authors: Saruwatari Masatoshi , Kimura Tatsuya , Otsuka Kenju
Published: February 2003

Room-temperature cw operation of a miniaturized LNP laser pumped with a 0.87-μm semiconductor laser is reported. This device has a low threshold, 140 μW, for an Ar ion laser pump, which corresponds to 83 μW at 0.87 μm, and shows nearly single longitudinal mode operation, even at 10 times above threshold. By using a 0.80-μm 25-mW semiconductor laser pump and by an optimized output coupling design, 3.8-mW output and 15% optical conversion efficiency are expected.
Elastomeric optical waveguide modulators
Authors: Maher J. , Schank R. L. , Pfister G.
Published: February 2003

We report modulation of light in planar optical waveguides of polydimethylsiloxane (PDMS) elastomers by a reversible electromechanical deformation of the thin film in the beam path. Modulation frequencies up to 140 kHz have been demonstrated in Dow Corning DC410 PDMS.
Nd-doped yttrium aluminum garnet with improved fluorescent lifetime of the 4F3/2 state
Authors: Singh S. , Bonner W. A. , Grodkiewicz W. H. , Grasso M. , Van Uitert L. G.
Published: February 2003

YAG:Nd polycrystals have been prepared in which the fluorescent lifetime of the 4F3/2 state is ∼420 μsec, in excellent agreement with the previously measured cross section and branching ratios. When such polycrystals are either fused or used to pull single crystals from melt, the fluorescent lifetime is reduced to ∼280 μsec. This is attributed to the creation of defects at high temperatures which can act as quenching centers. Various mechanisms for nonradiative decay of 4F3/2 are also discussed.
Longitudinal mode beat intensities in a cw HF chemical laser
Authors: Wang C. P. , Varwig R. L.
Published: February 2003

Longitudinal mode beat intensities in a free-running cw HF chemical laser have been investigated. A simple expression was derived that describes the variation of beat intensity with tuning frequency. Experimental observations of the variation of beat intensity with tuning frequency in a HF chemical laser agree with the theoretical prediction.
Enhanced localized degradation and anomalous emission spectra of Ga1−xAlxAs double heterostructure lasers induced by fabrication processes
Authors: Newman D. H. , Godfrey R. F. , Goodwin A. R. , Lovelace D. F.
Published: February 2003

Oxide-insulated stripe geometry double heterostructure lasers have been fabricated with and without a deep (1.3 μm) zinc diffusion prior to alloyed contacting. The two processes were found to result first in emission spectra indicative of significant differences in the point defect complex densities in the device active regions, and second in distinctly different modes of dark effect degradation.
14- and 16-μ gasdynamic CO2 lasers
Authors: Manuccia T. J. , Stregack J. A. , Harris N. W. , Wexler B. L.
Published: February 2003

Laser action at 16 μ has been obtained between the (02°0) and (0110) levels as well as between the (10°0) and (0110) levels at 14 μ. A 9- or 10-μ saturating pulse equilibrates the (001) level with either the (02°0) or (10°0) level and creates the transient 14- or 16-μ inversion. Extraction efficiencies of 20% have been achieved on a single pulse. Repetition frequencies of 200 Hz have been achieved using a single Q-switched cavity.
Electrochemical studies of the viologen system for display applications
Authors: Belinko K.
Published: February 2003

The electrochemical and electro-optical behavior of aqueous solutions of diheptyl viologen dibromide on tin oxide conductive glass electrodes was investigated. The viologen dication was found to undergo reduction in two distinct cathodic processes. The first cathodic step leading to the formation of the insoluble purple viologen complex was found to be reversible. The second reduction process was found to be irreversible and resulted in poisoning of the electrode surface. The failure mode of display devices based on the viologen system is attributed to the formation of this second reduction product.
Stored energy in a cold-rolled metallic glass
Authors: Chen H. S.
Published: February 2003

The relaxation spectra of a cold-rolled Pd-Cu-Si glass are very similar to that of the initially quenched glass, except for the low-temperature peak at 400 °K. About 4% of expended energy is stored in the glass. A possible mechanism is that the stored energy arises from local heating and quenching in shear bands. The bandwidth and the stored energy in the shear bands are of the order of 2500 Å and 2.5×104 erg/cm2, respectively.
Suppression of defect formation in GaAs layers by removing oxygen in LPE
Authors: Ishii Makoto , Kan Hirofumi , Susaki Wataru , Ogata Yoshihiro
Published: February 2003

The oxygen concentration in the ambient gas during liquid phase epitaxial growth processes was quantitatively analyzed. The oxygen influences the formation of defects such as saucer pits and so-called ’’dark spot defects’’ and the carrier concentration of grown layers. Reducing the oxygen concentration less than 0.03 ppm, the defect densities drastically decrease in GaAs grown layers.
Observation of large dc supercurrents at nonzero voltages in Josephson tunnel junctions
Authors: Niemeyer J. , Kose V.
Published: February 2003

Large dc supercurrents at nonzero voltages are observed in dc current-biased small Josephson tunnel junctions of the type PbIn- (PbIn)xOy-Pb with critical current densities j0 ranging from 2×102 to 2×105 A/cm2. The dependence of the hysteresis on j0 and the form of the subharmonic energy gap structure are compared with the theoretical results of McDonald et al.
Fabrication of multifilament Nb3Sn conductors
Authors: Koike Y. , Shiraki H. , Murase S. , Suzuki E. , Ichihara M.
Published: February 2003

Multifilament conductors have been fabricated using niobium tubes with a sheathed tin-copper alloy inside and pure copper matrix outside. These composites have good workability, cold drawn without any intermediate heat treatment. Sample evaluation has included measurements of critical temperature, resistivity, and critical current density. The Nb3Sn formed by this method has much higher critical current density than the previous one with approximately the same tin concentration (12 at.%), but lies on the line extrapolated from the bronze method over the solid solubility limit.
Magnetostatic wave propagation in a periodic structure
Authors: Sykes C. G. , Adam J. D. , Collins J. H.
Published: February 2003

Magnetostatic wave propagation at microwave frequencies through a periodic structure formed by selectively etching the surface of an epitaxial yttrium iron garnet (YIG) film is reported. Experimental insertion loss data obtained in the 2–4-GHz range from a structure comprising 20 grooves each 1 μm deep and 30 μm wide, and each separated by 120 μm, formed in a 9-μm-thick YIG film are in good agreement with theory based on repetitively mismatched transmission lines.
High-efficiency high-average-power second-harmonic generation with CdGeAs2
Authors: Menyuk N. , Iseler G. W. , Mooradian A.
Published: February 2003

Average second-harmonic power at 5.3 μm exceeding 0.75 W with a 17% power conversion efficiency has been obtained by pumping a CdGeAs2 crystal, cooled to near 77 K, with a Q-switched CO2 laser. Average and peak conversion efficiencies of 21 and 30%, respectively, were achieved at a pulse rate of 1.5 kHz. In cw operation the crystal gave a second-harmonic output of 73 mW with a conversion efficiency near 0.5%.
Electron-beam-controlled discharge pumping of the XeF laser
Authors: Mangano J. A. , Jacob J. H. , Dodge J. B.
Published: February 2003

Laser action of XeF has been obtained in atmospheric-pressure mixtures of 0.1% NF3, 0.4% Xe, and 99.5% Ar with electron-beam-controlled discharge pumping. The mean discharge current and voltage were 75 A/cm2 and 11 kV/cm, respectively, at 4 atm total pressure. The high-energy E-beam current was 12 A/cm2. Mechanisms for creating XeF* in a discharge are discussed. Physical processes which limit the intrinsic efficiency to 0.3% in the present device are also discussed.
HgSe, a highly electronegative stable metallic contact for semiconductor devices
Authors: Best J. S. , McCaldin J. O. , McGill T. C. , Mead C. A. , Mooney J. B.
Published: February 2003

Schottky barriers formed by the highly electronegative substance HgSe on n-ZnS and on n-ZnSe have been characterized by capacitance-voltage and photoresponse measurements. The barriers are about 0.5 eV greater than Au barriers on these n-type substrates. HgSe contacts are stable under ambient conditions and are easily fabricated, making them attractive for device use.
Optimum bulk series resistance of the Schottky-barrier solar cell
Authors: Dubey P. K.
Published: February 2003

We suggest that the efficiency of a Schottky-barrier (SB) solar cell could be subtantially increased (by as much as 2%) by making an optimum choice of the bulk series resistance (or the dopant concentration in the semiconductor) rather than minimizing it to zero. Thus we show that there exists an optimum nonzero bulk series resistance of SB solar cell for which the power conversion efficiency is maximum. For an n-type GaAs/Au SB solar cell, this optimum series resistance is calculated to be 0.2 Ω corresponding to a dopant concentration of 8×1013 cm−3.
Walker-type velocity oscillations of magnetic domain walls
Authors: Vella-Coleiro G. P.
Published: February 2003

We report stroboscopic observations of the radial motion of a magnetic bubble domain wall in an epitaxial LuGdAl iron garnet film. At high drive fields, initial velocities up to 9500 cm/sec were measured, and the domain wall was observed to move backwards during the field pulse, in agreement with calculations based on the Walker model.
Observation of the optoacoustic effect in the microwave region
Authors: Diebold Gerald , McFadden David L.
Published: February 2003

The microwave analog of the optoacoustic effect has been observed. Collisional relaxation of absorbed microwave energy between Zeeman magnetic sublevels of gaseous molecular oxygen results in the production of an acoustical signal which is detected by a sensitive microphone.
Orientation dependence of defect structure in EFG silcion ribbons
Authors: Garone L. C. , Rao C. V. Hari , Morrison A. D. , Surek T. , Ravi K. V.
Published: February 2003

Sustained growth of long lengths of silicon ribbons by the edge-defined film-fed growth (EFG) technique is shown to result in the attainment of an ’’equilibrium’’ defect structure and orientation by the crystals. The structure consists of parallel defect boundaries parallel to the edges of the ribbon with a ribbon orientation of {110} 〈211〉. The influence of seed orientation on the attainment of this structure has been examined.
Possible new sputtering mechanism in track registering materials
Authors: Haff P. K.
Published: February 2003

The ’’ion explosion’’ model of track production in dielectric materials in investigated as a possible source of sputtered particles at high bombarding energies.
Selective black absorbers using MgO/Au cermet films
Authors: Fan John C. C. , Zavracky Paul M.
Published: February 2003

Cermet MgO/Au films prepared by rf sputtering are found to be highly absorbing in the solar spectrum and highly transparent in the infrared. Excellent selective absorbers, with solar absorptivity of over 0.9 and infrared emissivity of less than 0.1, have been produced by depositing such films on metal substrates. Films deposited on Mo-coated stainless steel are stable in air up to 400 °C.
Dark-line defects induced by mechanical bending in GaAs-Ga1−xAlxAs double-heterostructure wafers
Authors: Kishino Seiĝo , Chinone Naoki , Nakashima Hisao , Ito Ryoichi
Published: February 2003

A 〈110〉-oriented dark-line defect (DLD) has been induced by mechanical bending in GaAs1−xAlxAs double-heterostructure (DH) wafers. Both the concave upward and the convex upward bending (with the DH epitaxial layer as the upward surface) of the DH wafer has been carried out using a four-point bending technique. The DLD formation has shown both the stress-direction dependence and the asymmetry of the DH wafer. Photoluminescence topography has shown that the characteristics of the DLD’s are exactly the same as those of the optically induced DLD’s. From experimental results, it is conjectured that a glide-multiplication mechanism is probably acceptable for the production of the 〈110〉 DLD dislocations.
Pressure dependence of the atomic fluorine laser transition intensities
Authors: Hocker L. O. , Phi Trinh Bang
Published: February 2003

Grating tuning the helium-fluorine laser has led to single line output at 6967, 7037, 7128, 7202, 7311, 7489, 7755, and 7800 Å. A study of the pressure dependence of the output intensities of these lines unambiguously identifies them as transitions between the 2s2p4(3P)3p and 2s2p4(3P)3s configurations of fluorine.
Efficient photovoltaic heterojunctions of indium tin oxides on silicon
Authors: DuBow J. B. , Burk D. E. , Sites J. R.
Published: February 2003

Heterojunction diodes of indium tin oxide films sputtered onto p-silicon using ion beam techniques display significant photovoltaic effects when exposed to sunlight. Galvanomagnetic and optical measurments confirm that the oxide films are highly degenerate transparent semiconductors. At a tin oxide concentration of 10%, we observed an open-circuit voltage of 0.51 V, short-circuit current of 32 mA/cm2, fill factor of 0.70, and conversion efficiency of 12%. As the concentration was raised to 70%, the voltage remained steady, the current fell to 27 mA/cm2, and the fill factor fell to 0.60.
Crater-edge profiling in interface analysis employing ion-beam etching and AES
Authors: Taylor N. J. , Johannessen J. S. , Spicer W. E.
Published: February 2003

The crater edge formed in Si-SiO2 films by appropriate ion-beam etching provides an angle-lapped surface analogous to that produced by usual mechanical means; however, the angle can be usefully reduced by 3 orders of magnitude, allowing much greater spatial resolution. Furthermore, in contrast to conventional depth profiling, the separation of the etching and analysis permits repetitive measurements to be made conveniently; a fact of considerable utility in interface analysis.
Tapped SAW delay line using LiNbO3 coupled to a CdS bulk-wave amplifier
Authors: Crowley J. D. , Giallorenzi T. G. , Weller J. F.
Published: February 2003

Piezoelectric leaky wave coupling of a LiNbO3 surface acoustic wave (SAW) to a CdS bulk wave is reported. A tapped SAW delay line is constructed using a CdS bulk-wave amplifier weakly coupled across an air gap to a yz LiNbO3 SAW delay line. Insertion loss of the tapped delay line with untuned IDT’s is 19 dB. Leaky wave coupling contributes only 1 dB to the insertion loss. Additional delayed pulses 2.5 dB larger than the SAW are easily achieved.
An independently controllable multiline laser resonator and its use in multifrequency injection locking
Authors: Sheffield R. L. , Nazemi S. , Javan A.
Published: February 2003

A resonator configuration is described which makes it possible to obtain simultaneous laser oscillation on several preselected transitions without the coupling effect. This resonator is used in a multifrequency injection-locking system in which the energy of an atmospheric TEA CO2 laser is extracted in several preselected transitions.
A coefficients for spontaneous emission in CO
Authors: Lightman Allan J. , Fisher Edward R.
Published: February 2003

Simultaneous end light emission measurements of the first- and second-overtone bands of CO have been obtained in a flowing CO-N2-He laser plasma. Interpretation of the band structure using A coefficients from Young and Eachus show consistent agreement with observation up to v=26. This agreement supports the use of these A coefficients in laser and kinetic applications.
Electron-beam fabrication of 80-Å metal structures
Authors: Broers A. N. , Molzen W. W. , Cuomo J. J. , Wittels N. D.
Published: February 2003

Metal structures 100 Å high with sharply defined linewidths of 80 Å have been produced using an electron-beam fabrication process. A contamination resist pattern is written with a 5-Å 45-keV scanning electron beam in a 100-Å-thick Au-Pd film supported by a 100-Å carbon foil. The unprotected Au-Pd is removed by dc ion etching with 1-keV Ar ions. Unlike most electron-beam microfabrication processes, the resolution of the resulting structure is not limited by electron scattering, but by the grain size of the metal films. These structures should have direct application in a large number of device fabrication problems in electron and x-ray beam technology and they should provide masks for other microfabrication processes such as x-ray lithography.
Dissociation mechanism for solid-phase epitaxy of silicon in the Si 〈100〉/Pd2Si/Si (amorphous) system
Authors: Pretorius R. , Liau Z. L. , Lau S. S. , Nicolet M-A.
Published: February 2003

Solid-phase epitaxial growth (SPEG) of silicon was investigated by a tracer technique using radioactive 31Si formed by neutron activation in a nuclear reactor. After depositing Pd and Si onto activated single-crystal silicon substrates, Pd2Si was formed with about equal amounts of radioactive and nonradioactive Si during heating at 400 °C for 5 min. After an 1-sec annealing stage (450→500 °C in 1 h) this silicide layer, which moves to the top of the sample during SPEG, is etched off with aqua regia. From the absence of radioactive 31Si in the etch, it is concluded that SPEG takes place by a dissociation mechanism rather than by diffusion.
Enhanced crystallinity of silicon films grown from eutectic melt on aluminum sheets
Authors: Saito Takeshi , Seki Yasuo
Published: February 2003

Silicon films were grown from Al-Si eutectic melt directly formed on aluminum sheets. High-energy silicon atoms were deposited onto aluminum sheets at 420 °C in an argon discharge atmosphere of 5×10−4 Torr using an rf ion-plating system. A significant increase in the crystallinity of silicon films was observed from transmission electron diffraction studies. The mechanism of silicon eutectic growth on aluminum sheets is also discussed.
Hole conduction in Si3N4 films on Si
Authors: Weinberg Z. A.
Published: February 2003

Dominant hole conduction is observed in thin Si3N4 films deposited on silicon with holes being injected from either aluminum or gold electrodes. Hole transport is confirmed by employing a shallow junction diode detector. Such a diode can serve also as excellent means for separating conduction currents from transient displacement currents under pulsed conditions.
Electroluminescence in amorphous silicon
Authors: Pankove J. I. , Carlson D. E.
Published: February 2003

Electroluminescence has been obtained in forward-biased p-i-n diodes, and also in Schottky barrier diodes fabricated from discharge-produced amorphous Si. The emission at 78 °K in both electroluminescence and photoluminescence peaks at 1.28±0.08 eV in a 0.2-eV broad band with an external quantum efficiency of ∼10−3.
Piezoelectric DMOS strain transducers
Authors: Yeh K. W. , Muller R. S.
Published: February 2003

High-frequency strain transducers consisting of n-channel piezoelectric DMOS transistors have been constructed. These transducers have detected surface acoustic waves at 20 and 28 MHz. The transducers exhibit gauge factors of the order of 105 at dc.
A mesa p-n diode array acoustic surface wave convolver
Authors: Joly R.
Published: February 2003

A new type of airgap convolver has been constructed. It uses a mesa p-n diode array, instead of the usual silicon slab, and narrow rails for supporting the diode array. Several different modes of operation for imaging have been demonstrated with this device.
Correlation with the storage convolver
Authors: Borden P. G. , Kino G. S.
Published: February 2003

A p-n junction type storage convolver has been used to correlate FM chirps with time-bandwidth products of approximately 90, and to correlate echoes from an acoustic A-scan system which have been badly distorted by the source transducer.
Magnetic inhibition of surface flashover of insulators in vacuum
Authors: Bergeron Kenneth D. , McDaniel Dillon H.
Published: February 2003

The possibility of preventing high-voltage surface flashover of insulators in vacuum by means of a strong magnetic field perpendicular to the electric field and parallel to the insulator surface is investigated theoretically. A simple model predicts that with the right choice of insulating material one can design diodes and transmission lines so that the magnetic field from the line current inhibits the secondary-electron-emission avalanche which is believed to play an important role in the flashover process.
Limitation in growth time of stimulated Compton scattering in x-ray regime
Authors: Hasegawa Akira , Mima Kunioki , Sprangle P. , Szu H. H. , Granatstein V. L.
Published: February 2003

We present a classical theory of stimulated Compton scattering by an intense relativistic electron beam. The growth rates in the x-ray regime are obtained for two types of excitation: (i) an incident electromagnetic wave and (ii) a spatially rippled static magnetic field. Nonlinear spread of the beam velocity distribution by the pump field reduces the growth rate. The limiting growth rate depends only on the beam quality and becomes ∼1 μsec−1 using the best available beam.
Dose dependence of the photon emission from sputtered aluminum atoms during helium irradiation
Authors: Braun M. , Emmoth B.
Published: February 2003

Polycrystalline aluminum samples are irradiated with 40-keV He+. At moderate target temperatures (∼0.3Tm) a prominent and distinct enhancement of the light intensity from sputtered excited aluminum atoms is observed after implantation to a critical dose of 4×1017 He+/cm2. It is shown that this effect is associated with a sudden increase in the erosion rate of Al and in the surface exfoliation due to radiation blistering. At higher target temperatures (∼0.7Tm) a less pronounced increase in the photon intensity and a different surface structure is observed.
On the sputtering of binary compounds
Authors: Haff P. K. , Switkowski Z. E.
Published: February 2003

A simple physical model is presented to describe some aspects of the sputtering of compound targets. In particular, expressions are developed for the partial sputtering yields for binary systems in terms of the elemental sputtering rates, the stoichiometric concentrations, and surface binding energy. The partial yields depend nonlinearly on the bulk target concentrations. Comparison of the theoretical predictions with the data on sputtering of PtSi, NiSi, and Cu3Au indicates that the general features are well described.
High-sensitivity depth profiling of arsenic and phosphorus in silicon by means of SIMS
Authors: Wittmaack K.
Published: February 2003

Secondary ion mass spectrometry has been used for depth profiling of arsenic and phosphorus in silicon. High-sensitivity analysis down to concentrations of a few 1017 atoms/cm2 could be achieved by energy discrimination against mass interfering molecular secondary ions.
Phase-matched generation of 2314 Å in KB5O8⋅4 H2O
Authors: Kato K.
Published: February 2003

Third-harmonic generation of a ruby laser has been achieved in a potassium pentaborate tetrahydrate (KB5O8⋅4 H2O) crystal through type-1 frequency mixing of the fundamental and second-harmonic radiation. An over-all power conversion efficiency of 0.2% was obtained.
Optical waveguides formed by low-energy electron irradiation of silica
Authors: Houghton A. J. , Townsend P. D.
Published: February 2003

We have demonstrated that low-energy electron irradiation of silica glass leads to a sufficient change in the refractive index to form optical waveguides. A peak enhancement of at least 0.9% is achieved by the deposition of some 1024 keV cm−3 and is stable to at least 200 °C. This energy requirement is consistent with measurements of lattice compaction in silica which also reaches a maximum value when ∼1024 keV cm−3 is deposited in ionization or electronic excitations. (The change is thought to be the result of irradiation damage). It is noted that changes induced in this way might have application in both integrated optics and graded index fibers.
Tunable quantum counter for far-infrared radiation
Authors: Lengfellner H. , Pauli G. , Heisel W. , Renk K. F.
Published: February 2003

We report on a quantum counter which converts far-infrared radiation to visible light. The 891-Ghz radiation of an HCN laser, absorbed in optically pumped ruby by the transition Ē (2E) →2Ā (2E), was detected by an increased R2 fluorescence. By Zeeman splitting of the 2E levels the narrow-band detector was tuned to the laser line.
Efficient second-harmonic generation in three-dimensional LiNbO3 optical waveguide
Authors: Uesugi Naoshi , Kimura Tatsuya
Published: February 2003

Highly efficient second-harmonic generation using a titanium in-diffused LiNbO3 three-dimensional optical waveguide was performed with the cw Nd : YAG laser at 1.064-μm wavelength. The phase-matching condition to convert the TE00 fundamental frequency to the TM00 or TM20 second harmonic was demonstrated by adjusting the crystal temperature. The conversion efficiency is 1.5×10−4 at 2-mW fundamental input power under the phase-matching condition. By using a low-loss LiNbO3 optical waveguide, equipped with highly reflective cavity mirrors on the input and output surfaces, parametric oscillation is expected.
Switching, storage, and erasure effects in a superconducting thin film
Authors: Testardi L. R.
Published: February 2003

Thin niobium films can be switched from a superconducting to a resistive state permanently by application of a short electrical pulse. Application of a short pulse of opposite polarity returns the film to the superconducting state.
Refractive index of a native oxide anodically grown on GaAs
Authors: Barnes P. A. , Schinke D. P.
Published: February 2003

The refractive index of an anodically grown oxide on GaAs has been measured throughout the visible and near infrared and the data fitted to a single oscillator Sellmeier equation. Accurate refractive-index data is required for possible use of anodic oxides as antireflection coatings on GaAs electro-optic devices. For 11 as-grown oxides the measured refractive index for λ=632.8 nm was n=1.7786±0.0138, while for five annealed oxides (259 °C for 1 h in N2) n=1.7469±0.0095. The calculated refractive index of annealed oxides at the emission wavelengths of interest for GaAs-AlGaAs fiber communication sources is n=1.724±0.006 at λ=890±20 nm.
Two-photon absorption spectroscopy of the intrinsic exciton fine structure in CdS
Authors: Nguyen V. T. , Damen T. C. , Gornik E.
Published: February 2003

We have observed the fine structure of two-photon excited P states in CdS by focusing a dye laser and a CO2 laser into the crystal. From the clear-cut polarization selection rules, we demonstrate that the visible photon creates a virtual 1S exciton and, subsequently, the infrared photon brings it to the final P state. On this basis, we have calculated the two-photon absorption coefficient which is in good agreement with experimental data.
Electronic effects on dislocation velocities in heavily doped germanium
Authors: Patel J. R. , Testardi L. R.
Published: February 2003

Based on a model proposed by Frisch and Patel, the dislocation velocity behavior in heavily doped germanium has been analyzed using Fermi-Dirac statistics. Both the isothermal doping dependence and the temperature dependence of the change in dislocation velocity with doping can be accounted for by assuming an acceptorlike dislocation energy level, somewhat above the center of the energy gap.
A method to determine bulk lifetime and diffusion coefficient of minority carriers; application to n-type LPE GaP
Authors: van Opdorp C. , Werkhoven C. , Vink A. T.
Published: February 2003

It is shown that the bulk lifetime and diffusion coefficient of minority carriers in semiconductor layers can accurately be determined from the dependence of near-band-edge exciton-luminescence decay on layer thickness. This method is applied to n-type LPE GaP using laser-pulse excitation. As we expected, large differences are observed between the actual bulk lifetime and the measured effective lifetime: the largest ratio amounts to a factor of 4. Bulk lifetimes as high as 5 μs and hole diffusion coefficients between 2.6 and 3.1 cm2/s are found at room temperature.
Extension of the Schottky barrier detector to 70 μm (4.3 THz) using submicron-dimensional contacts
Authors: Hodges D. T. , McColl M.
Published: February 2003

Schottky barrier diode detection in both video and mixing modes of operation has been extended to 4.252 THz (70.5 μm) using 0.5-μm-diam diodes fabricated from heavily doped nonepitaxial n-type GaAs. These ultrasmall, and consequently ultralow capacitance, junctions were prepared using electron-beam lithography and have yielded the smallest reported series-resistance junction-capacitance product for a Schottky barrier diode. The potential for extending diode operation to still higher frequencies is discussed.
Photoluminescence from Mg-implanted GaAs
Authors: Yu Phil Won , Park Y. S.
Published: February 2003

Photoluminescence measurements at 4.2 °K were used to study the emission behavior and the annealing characteristics in Mg-ion-implanted layers in GaAs. Radiative recombination due to the donor-acceptor pairs and free electrons with holes bound to acceptors involving Mg was observed. The ionization of Mg is esti mated to be 28±2 meV. The donor-acceptor pair band shows a large energy shift with the change of the excitation intensity. Annealing at the temperatures 750–900 °C sufficient to optically activate Mg ions implanted and to recover from lattice damages.
Thermal degradation of homoepitaxial GaAs interfaces
Authors: Lum W. Y. , Wieder H. H. , Koschel W. H. , Bishop S. G. , McCombe B. D.
Published: February 2003

Photoluminescence techniques have been used to detect and characterize p-type conducting layers formed on the surface of semi-insulating GaAs substrates and at the liquid phase epitaxial layer–GaAs substrate interface during pregrowth heat treatment. These layers contain ∼1017 cm−3 shallow acceptors and a high density of arsenic vacancy complexes, and can be eliminated by pregrowth Ga etching of the substrate.
Subpicosecond pulses from a cw double mode-locked dye laser
Authors: Yasa Z. A. , Dienes A. , Whinnery J. R.
Published: February 2003

Simultaneous picosecond and subpicosecond pulses are generated in a cw double mode-locked dye laser. The rhodamine 6G dye pulses are of the order of 0.5 psec long, while the saturable absorber cresyl violet lases simultaneously with pulse durations of around 1 psec.
Chirped-grating demultiplexers in dielectric waveguides
Authors: Livanos A. C. , Katzir A. , Yariv A. , Hong C. S.
Published: February 2003

A wavelength-selective beamsplitter has been realized by fabricating chirped (variable period) grating in an optical waveguide. This beamsplitter can demultiplex a signal traveling in a fiber and send each frequency component to a different fiber.
Integrated interferometric reflector
Authors: Streifer W. , Scifres D. R. , Burnham R. D.
Published: February 2003

We propose a new integrated interferometric reflector (IIR) with electrical control. The IIR is suitable for incorporation in integrated optical devices as a laser reflector.
Monte Carlo calculations on hot electron energy tails
Authors: Phillips A. , Price P. J.
Published: February 2003

A Monte Carlo procedure which makes it practicable to extend the calculation of hot electron distribution functions to rarely occupied ranges of the electron state is described. The method is illustrated by a calculation of the energy distribution, for semiconductor electrons in an electric field, as a function of distance in the drift direction from the initial position. For energies comparable to the ultimate average energy, the ’’thermalization’’ of the distribution occurs close to the starting point, but with increasing energy it occurs at increasing distances.
Generation of interface states due to emission of leakage electrons from silicon substrate into silicon dioxide
Authors: Huang H.-C. W.
Published: February 2003

Experimental evidence of interface state generation due to the emission of leakage electrons from the silicon substrate into SiO2 is presented. Interface states were measured on MNOS capacitors before and after temperature-bias stress, where the electron emission process occurred, using the high-frequency and quasistatic C-V technique. Electrical access to the silicon surface to vary the space-charge width was made by the use of a very small diffusion underneath the field plate. The generation of interface states which can in turn cause device degradation is undoubtedly a reliability concern.
Lateral current confinement by reverse-biased junctions in GaAs-AlxGa1−xAs DH lasers
Authors: Tsang W. T. , Logan R. A.
Published: February 2003

Two methods are described for fabrication of a DH stripe-geometry laser where lateral current confinement is obtained with reverse-biased junctions on both sides of the active layer. Threshold current densities, comparable in values to optimum values achieved in other stripe geometry lasers, are obtained as a function of top channel widths for lasers with single and double current confinement. The lasers exhibit clean stable mode patterns with excellent linearity of the optical output power as a function of injection current. Lasers with channel widths ≲14 μm operate in the lowest-order transverse mode in the junction plane for currents up to ∼two times the threshold (an output power of 16 mW per mirror).
Analyses of sputtered films of Nb3Ge
Authors: Wu C. T. , Kammerdiner Lee , Luo H. L.
Published: February 2003

The analyses of Nb-Ge films prepared by sputtering with a modified rf arrangement are reported. The results indicate the importance of thermalization of sputtered particles for the formation of the high-transition-temperature compound Nb3Ge.
Fluxon interactions
Authors: McLaughlin D. W. , Scott A. C.
Published: February 2003

A simple perturbation method is used to study fluxon (soliton) interactions on a Josephson transmission line (JTL). This technique efficiently provides information needed in the design of JTL computer circuits. We study (i) fluxons interacting with other fluxons in the presence of both dissipation and an externally controlled current bias and (ii) fluxons interacting with microshorts. The dynamics of fluxon pinning to a microshort is described and threshold conditions for fluxon-antifluxon annihilation are presented. We emphasize that in this process free fluxons become bound into ’’breathers’’, which in turn decay into ’’photons’’ of the Josephson waveguide.
Electronically variable delay using ferroelastic-ferroelectrics
Authors: Coldren L. A. , Lemons R. A. , Glass A. M. , Bonner W. A.
Published: February 2003

Coupled ferroelastic-ferroelectric domains in the rare-earth molybdates can be used to provide electronically variable analog delay in simple acoustic delay line structures. Delay variations of ∼3% for surface acoustic waves and 12% for bulk longitudinal waves are demonstrated with gadolinium molybdate [Gd2 (MoO4)3] crystals. Estimates of a number of parameters useful in evaluating device performance are made from experimental measurements.