bluuebunny/crossref_metadata_2025 huggingface dataset:
High-efficiency high-power coherent uv generation at 266 nm in 90° phase-matched deuterated KDP
Authors: Liu Yung S. , Jones W. B. , Chernoch J. P.
Published: February 2003

We report high-efficiency high-power uv generation at 266 nm by frequency quadrupling of Nd laser using two deuterated KDP crystals. An angle-tuned type-II phase-matched (eoe-interaction) deuterated KDP crystal is used for doubling 1.064 μm and a temperature-tuned 90° phase-matched deuterated KDP crystal is used, for the first time, for doubling 532 nm to 266 nm. Results indicate that an average uv power of several watts with an over-all quadrupling efficiency of around 20% is obtainable, and that high peak uv power on the order of 10 GW with an efficiency of greater than 35% can be expected for subnanosecond pulses. The high peak uv power is potentially useful for fusion studies.
Temporal oscillations in the output from a gas-dynamic laser with an unstable resonator
Authors: Alme Marvin L.
Published: February 2003

We have performed numerical studies of self-oscillation instabilities which can result from the upstream-downstream feedback in a gas-dynamic laser (GDL) with an unstable resonator. In this letter, which extends previous work by Dreizen and Dykhne, we show that inclusion of a simple model for CO2 pumping by N2 strongly damps any oscillations in the output intensity.
Plasma oxidation of GaAs
Authors: Chang R. P. H. , Sinha A. K.
Published: February 2003

A new process for plasma oxidation of GaAs has been developed. Oxide films formed by this simple one-step dry process have amorphous structure, with composition and thickness uniformity better than ±10% over areas ≲1 cm2. They have a gallium-to-arsenic ratio of nearly one. The electrical properties (I-V, C-V) of the films are such that this process may be useful in device fabrication.
Capacitor-shunted Josephson junction for improved coupling with microwave fields
Authors: Morisseau D. , Lewiner J. , Lewandowski S. J. , Jung G.
Published: February 2003

We report the fabrication of a capacitor-shunted Josephson junction and its use as a microwave device with improved coupling to microwave fields. The junction was evaporated on a thin plastic substrate which was subsequently folded like a flat-spring clip in order to make a circular coupling loop terminated by a parallel-plate capacitor. The capacitor short-circuits the loop for high-frequency currents but keeps it open for dc currents, rendering possible the application of dc bias to the junction. The folded junction was observed at X band to couple 20 dB better to rf power than the same junction extended flat.
The use of intense ion beams for heating long ϑ-pinch plasmas to thermonuclear temperatures
Authors: Ott Edward , Sudan R. N.
Published: February 2003

Motivated by recent advances in the production of intense ion beams, we consider the possible utility of such beams for heating a long thin ϑ-pinch plasma to thermonuclear temperatures. It is found that ion beams offer an alternative to previously proposed schemes utilizing CO2 laser beams and intense relativistic electron beams.
Model for current-driven motion of magnetic bubble lattices
Authors: Henry G. R.
Published: February 2003

A model (with no free parameters) for the current-driven motion of magnetic bubble lattices is developed, consisting of massless damped elements (bubbles) connected by linear springs (representing the bubble-bubble interaction). For the specific system considered, the model yields a saturation velocity of about 1 m/sec, in agreement with experiment. The variation of bubble diameter is not explicitly computed; treatment of this additional degree of freedom should produce a still more realistic model.
Determination of the lasing threshold in stripe-geometry double-heterostructure junction lasers
Authors: Paoli Thomas L.
Published: February 2003

Measurements of the noise fluctuations in the light intensity emitted by stripe-geometry junction lasers are used to relate the threshold for amplitude-stabilized oscillation to the behavior of the first and second derivatives of the diode’s electrical characteristics. The amplitude stabilization is observed to begin at a current above the point where the second-derivative signal attains its maximum value but below the current at which the junction voltage is fully saturated. Consequently, the electrical derivatives do not, in general, sense the exact threshold current but only provides bounds on its value.
Work function of LaB6
Authors: Yamauchi H. , Takagi K. , Yuito I. , Kawabe U.
Published: February 2003

By means of Richardson plots, low work functions of 2.3–2.4 eV have been measured for three cyrstal planes including (100) of single-crystal LaB6. Modifying Smith’s model of a metallic surface, the work function of LaB6 has been theoretically estimated for a jellium model at 2.31±0.05 eV which is in good agreement with experimental values.
Effect of distributed charge in the nitride of an MNOS structure on the flat-band voltage
Authors: Chang Joseph J.
Published: February 2003

Closed-form expressions have been obtained for the flat-band voltage of an MNOS structure with charge carriers trapped in the nitride bulk according to the Arnett-Yun model. Within the applicable limit of this model, the following observations can be made from these flat-band voltage expressions: When σQ (t) ≃4 or larger, the carrier distribution can be fairly accurately approximated by a step function, so far as flat-band voltage is concerned. When σQ (t) ≃0.1 or smaller, the centroid ? of the trapped carrier distribution approaches the trapping distance x0. σ is the capture cross section and Q (t) the total number of injected carriers at time t.
The on-state of the amorphous semiconductor device
Authors: Buckley W. D.
Published: February 2003

A simple relaxation analysis is presented to show that the transient on characteristics of the amorphous semiconductor device are consistent with bulk filament characteristics.
Shear measurements in shock-loaded solids
Authors: Gupta Y. M.
Published: February 2003

An experimental method is described which permits internal measurements of pressure and shear (IMPS) in shocked solids. The conceptual feasibility of the measurement was demonstrated by two experiments on polymethyl methacrylate (PMMA). The ability to make internal shear measurements raises interesting possibilities for shock-wave studies in solids.
Ultraviolet-preionized discharge-pumped lasers in XeF, KrF, and ArF
Authors: Burnham R. , Djeu N.
Published: February 2003

Lasers in XeF, KrF, and ArF have been excited in a uv-preionized transverse electric discharge. Laser pulse energies exceeding 100 mJ with peak powers of several megawatts have been produced with electrical efficiencies of over 1%.
16 μ and 8.5 μ generated via stimulated Raman process in potassium vapor
Authors: Kung R. T. V. , Itzkan I.
Published: February 2003

16-μ and 8.5-μ tunable lasing outputs were obtained from two sequential stimulated Raman scattering processes in K vapor using two visible dye lasers concurrently. Greater than 10 mW of 16-μ output was obtained for a 1-kW pump power. Tuning range of 2–4 cm−1 was observed. Kinetic information on the quenching of the 4P levels of K was deduced from the 16-μ signal amplitudes as a function of the delay time between the two lasers.
Interdiffusion mechanisms in Ag-Au thin-film couples
Authors: Kirsch R. G. , Poate J. M. , Eibschutz M.
Published: February 2003

The roles of grain-boundary and bulk diffusion in thin-film couples of Ag-Au have been elucidated by comparing interdiffusion profiles in single-crystal and polycrystalline couples. The use of self-supporting couples, and Rutherford backscattering for depth analysis, greatly simplify interpretation of the data. Room-temperature grain-boundary diffusion is observed in polycrystalline couples with a diffusion coefficient ∼−1014 cm2 sec−1. On annealing these polycrystalline films, at temperatures ⩽400 °C, an initial fast interdiffusion is observed followed by a slower process; models for this behavior are presented.
Phase-matched second harmonic generation in a periodic GaAs waveguide
Authors: van der Ziel J. P. , Ilegems M. , Foy P. W. , Mikulyak R. M.
Published: February 2003

Using a tunable laser operating near 2 μm, second harmonic generation was observed in a GaAs waveguide having a grating etched in one interface. Phase matching occurs when β2−2β1−ϑ=0, where ϑ=2π/Λ is the wave vector of the grating of period Λ and β1 and β2 are the fundamental and harmonic wave vectors.
An electro-optic technique for display and shaping of subnanosecond laser pulses
Authors: Massey G. A. , Elliott R. A.
Published: February 2003

We analyze a focusing interaction between a parabolic voltage pulse traveling in a transmission line filled with nonlinear dielectric and a laser pulse which crosses the guide at right angles. In this interaction the voltage pulse, which is about 1 nsec in duration, creates an effective cylindrical lens that moves across the optical wave front with a velocity greater than 109 cm/sec. The light is imaged by this disturbance to a focal spot which translates at the same velocity, producing the effect of a streak camera without the necessity of a photocathode and electron deflection. By placing a spatial filter, rather than a detector array, in the focal plane, subnanosecond shaping or gating of the input pulse can be achieved very simply.
High-efficiency ion-implanted lo-hi-lo GaAs IMPATT diodes
Authors: Bozler C. O. , Donnelly J. P. , Murphy R. A. , Laton R. W. , Sudbury R. W. , Lindley W. T.
Published: February 2003

A dc-to-rf conversion efficiency of 37% combined with an output power of 3.4 W at 3.3 GHz has been obtained from a Schottky-barrier GaAs IMPATT diode having a lo-hi-lo profile. The donor spike or clump was produced by implanting silicon into an epitaxial layer with a n-type concentration of 1.65×1015 cm−3. Pyrolytic Si3N4 was used to encapsulate the GaAs during the postimplantation anneal. For these devices, the Si3N4 deposition procedure was found to be critical and had to be optimizied to achieve reproducible results. The devices have had very uniform electrical characteristics, and a large yield of devices with greater than 30% efficiency has been obtained. These results indicate that implantation can be used to produce lo-hi-lo IMPATT’s with significantly higher device yields than have been obtained by epitaxial techniques.
Magnetic-field-dependent attenuation of surface waves by nickel thin films
Authors: Krischer Charles , Feng Ian , Block Jeffrey B. , Levy Moises
Published: February 2003

A strong magnetic-field-dependent room-temperature attenuation of 618-MHz surface waves propagating on a Y-cut quartz substrate coated with a 200-Å nickel film was observed. The attenuation could be varied over a range of more than 25 dB/cm by external magnetic-field changes of less than 10 Oe.
Regrowth behavior of ion-implanted amorphous layers on 〈111〉 silicon
Authors: Csepregi L. , Mayer J. W. , Sigmon T. W.
Published: February 2003

The regrowth of Si crystal from amorphous layers created by Si implantation into 〈111〉, 〈100〉, and 〈110〉 Si was studied. Channeling effect measurements show that the growths on the 〈110〉 and 〈100〉 substrates are epitaxial and linear with time. For the 〈111〉 samples the growth at 550 °C was significantly slower and nonlinear in time and the regrown layer contained a high concentration of defects. TEM micrographs indicate the presence of stacking faults and/or microtwins in the 〈111〉 samples.
X-ray ’’light pipes’’
Authors: Mosher D. , Stephanakis S. J.
Published: February 2003

A simple theory and experimental results are presented which describe the efficient transport of soft x radiation through hollow glass tubing by means of multiple grazing-incidence internal reflection. It is shown that a large number of such tubes can be used to remotely image weak plasma sources of soft x radiation. The efficiency of transport through bent tubes and the use of light pipes as low-pass filters for x radiation are discussed.
Selective excitation in charge-transfer collisions with Ne2
Authors: Bearman G. H. , Earl J. D. , Harris H. H. , Leventhal J. J.
Published: February 2003

The possible advantages of employing neon-dominated gas mixtures in e-beam laser cavities are discussed, and cross sections for selective excitation of N2+, CO+, and CO2+ in charge-transfer collisions between Ne2+ and N2, CO and CO2 are reported. The magnitudes of these cross sections (measured using beam techniques) compare favorably with analogous measurements involving He2+ reactant ions, suggesting that laser action in neon-dominated mixtures might be achieved. The addition of helium to the ion source was observed to increase the Ne2+ beam current; however, the accompanying increased photon yield was greater than the percentage increase in the beam current, indicating that vibrationally relaxed Ne2+ is preferred. It is suggested that ’’seeding’’ a neon-filled e-beam laser cavity with helium could increase the over-all efficiency of such a device.
Distributed-feedback color center lasers in the 2.5–3.0-μm region
Authors: Bjorklund G. C. , Mollenauer L. F. , Tomlinson W. J.
Published: February 2003

We have demonstrated pulsed distributed-feedback laser action in KCl:Li containing FA(II) color centers with spatially modulated concentrations. Laser outputs at various wavelengths between 2.6 and 2.8 μm have been observed with linewidths narrower than 0.2 nm. The absorbed pump power at threshold was 1.5 kW, and efficiencies of up to 6.7% were measured.
Current-phase relations as determinants of superconducting thin-film weak-link I-V characteristics
Authors: Jackel L. D. , Henkels W. H. , Warlaumont J. M. , Buhrman R. A.
Published: February 2003

The dc I-V characteristics of superconducting thin-film Sn-Au proximity bridges and uniform-thickness Sn microbridges have been carefully analyzed as a function of the directly measured current-phase relation (CPR). At sufficiently low dc current and voltage levels where heating and relaxation time effects are not important, the I-V characteristics are very well described by a shunted weak-link model that includes the proper dc CPR and a shunt resistance.
Shrinkage effect of stacking faults during HCl oxidation in steam
Authors: Shibayama H. , Masaki H. , Ishikawa H. , Hashimoto H.
Published: February 2003

The generation and shrinkage of stacking faults during HCl oxidation in steam were investigated. Carrier gas, N2 or O2, was bubbled through H2O and mixed with HCl. In wet O2+HCl oxidation, the faults expanded at the beginning of oxidation and then shrank rapidly. However, the shrinkage of the faults was not observed in wet N2+HCl oxidation. The presence of O2 in the atmosphere influences the shrinkage of stacking faults during HCl oxidation in steam. A thick oxide film without faults can be easily obtained in this oxidation.
Slip banding in Al single crystals produced by 10.6-μm laser pulses
Authors: Porteus J. O. , Soileau M. J. , Fountain C. W.
Published: February 2003

Slip bands produced by 100-nsec 10.6-μm focused laser pulses have been observed on clean annealed Al single-crystal targets with (111), (001), and (110) surface-plane orientations. At energy densities ≳37 J/cm2 the slip banding is not consistent with thermal stress, implying that evaporative compression is the dominant mechanism. This is supported by evidence from neutral particle emission. Possible evidence of thermal stress is present in slip banding observed near and below the threshold for melting. The relationship of observed slip to target orientation can be a valuable source of information on laser-induced stress fields.
Tungsten as a marker in thin-film diffusion studies
Authors: van Gurp G. J. , Sigurd D. , van der Weg W. F.
Published: February 2003

Vacuum-deposited tungsten of about 30-Å thickness has been used as a diffusion marker in the reaction between a thin Co film and Si. In order to produce a discontinuous W film, it is necessary first to deposit a Sn film with island structure and then W, after which the Sn is dissolved. It was found by MeV He+ backscattering analysis that the W is located at the Co-Co2Si interface, which means that Co is the dominant diffuser in Co2Si.
cw generation of multiple Stokes and anti-Stokes Brillouin-shifted frequencies
Authors: Hill K. O. , Johnson D. C. , Kawasaki B. S.
Published: February 2003

Continuous-wave laser action in multiply Brillouin-shifted spectral lines in a novel Fabry-Perot optical-fiber resonator is reported. Oscillation has been observed over a 200-GHz bandwidth and a total of 14 Brillouin-shifted lines have been detected. This Brillouin laser configuration is potentially a source of mode-locked picosecond pulses.
Synchronizable actively mode-locked Nd:glass laser
Authors: Tomov I. V. , Fedosejevs R. , Richardson M. C. , Orr W. J.
Published: February 2003

With the development of an actively mode-locked Nd:glass laser incorporating dynamic Q control, a single subnanosecond 1.06-μ pulse has been synchronized to a 1-ns-duration 10.6-μ CO2 laser pulse to within <400 ps.
Stress generation by electromigration
Authors: Blech I. A. , Herring Conyers
Published: February 2003

Stresses in aluminum thin films on TiN were studied in situ by transmission x-ray topography. Stress gradients were seen to build up in thin aluminum films during passage of electrical currents. The stresses are more compressive in the anode regions. These stress gradients seem to be a concomitant of the backflow responsible for the reported threshold in electromigration, and can probably be correlated quantitatively with it.
cw 1→0 CO chemical laser: Optical pumping of CO
Authors: Jeffers W. Q. , Ageno H. Y. , Wiswall C. E. , Kelley J. D.
Published: February 2003

The first operation of a cw CO chemical laser delivering nearly 1 W of power oscillation on the 1→0 vibrational band is reported. Experimental results and operating details with respect to 1→0 emission are discussed. Optical pumping of CO by the CO chemical laser is also reported; optically pumped absorption has been measured up to the 6→5 band.
KrCl laser oscillation at 222 nm
Authors: Murray J. R. , Powell H. T.
Published: February 2003

Laser oscillation has been observed on the 2Σ+ 1/2-2Σ+ 1/2 band of KrCl at 222 nm in an electron-beam-excited mixture of argon, krypton, and chlorine. The laser performance and spectral features of KrCl and KrF are compared.
Thin-film CuInSe2/CdS heterojunction solar cells
Authors: Kazmerski L. L. , White F. R. , Morgan G. K.
Published: February 2003

The fabrication procedures and characteristics of several thin-film p-CuInSe2/n-CdS heterojunction solar cells are presented. Two modes of operation (illumination through CuInSe2 or through CdS) are discussed. Efficiencies in the range of 4–5% are reported, under 100 mW/cm2 tungsten-halogen illumination for 1.2-cm2 devices. Included are the spectral response and J-V characteristics for these photovoltaic junctions.
Amplitude and phase modulation accompanying laser beam trapping in plasmas
Authors: Feit M. D. , Fleck J. A.
Published: February 2003

The self-trapping of laser beams in underdense plasmas or the propagation of laser beams in preformed favorable electron density distributions can be accompanied by gross distortions of pulse shape and spectrum. A simple theory is used to estimate the magnitude of these effects.
Acoustic properties of sputtered glass at microwave frequencies
Authors: Weglein R. D.
Published: February 2003

The published literature contains little information on the acoustic properties of thin dielectric films produced by sputter deposition. The longitudinal velocity and impedance of a sputter-deposited glass film, one-quarter wavelength thick, has been measured in the vicinity of 400 MHz. Such a layer produces a near-optimum acoustic power transfer between sapphire and water. Curve fitting the predicted return loss against frequency to the experimental impedance transformer response provides a convenient method for the determination of the layer’s acoustic properties.
Epitaxial structures with alternate-atomic-layer composition modulation
Authors: Gossard A. C. , Petroff P. M. , Weigmann W. , Dingle R. , Savage A.
Published: February 2003

Epitaxial structures grown by alternate monolayer depositions of GaAs and AlAs are reported. As many as 104 alternate (100) layers of GaAs and AlAs as thin as 1.0±0.1 and 1.0±0.1 monolayers, respectively, were deposited by sequential molecular beam epitaxial growth on a (100)GaAs substrate. Transmission electron microscopy showed the resultant films to be perfectly epitaxial with layered composition modulation of the expected periodicity. Their electronic properties were studied by optical absorption and luminescence.
Simple real-time light valves
Authors: Haas Werner E. L. , Dir Gary A.
Published: February 2003

A simple real-time light valve based on selenium and the cholesteric-nematic phase transition is described. The device is optically addressed and can be read out in real time with very intense white light sources without need for an optical blocking layer. Operation involves the absorption characteristics of the photoconductor and space-charge-limited currents. The principle can be extended to other combinations of photoconductors and electro-optic effects.
Ferromagnetic properties of some new metallic glasses
Authors: O’Handley R. C. , Hasegawa R. , Ray R. , Chou C.-P.
Published: February 2003

Continuously cast metallic glasses [METGLASR (trademark of the Allied Chemical Corporation) alloys] based on the transition metals (TM) iron, cobalt, and nickel can now be synthesized containing boron as the only metalloid. The different electron-donor effects of boron and phosphorus are clearly seen for the first time; each atom of these metalloids gives ∼1.6 and 2.4 electrons, respectively, to the TM d bands. Extrapolation of the available magnetic moment data suggests a nonzero moment on nickel in (TM)80B20 glasses. The boron-containing metallic glasses generally show higher Curie temperatures and room-temperature saturation magnetizations than mixed-metalloid glassy alloys of the same TM content.
Improvement of diffraction efficiency in surface-acoustic-optic devices by means of multilayered structure
Authors: Kushibiki J. , Chubachi N. , Shibayama K.
Published: February 2003

A strain-controlling film to change acoustic strain distributions in the interaction region between acoustic surface waves and optical guided waves is introduced to improve the Bragg-diffraction efficiency in surface-acoustic-optic devices. An improvement of about 2 orders of magnitude has been achieved in the efficiency of TM0-TM0 diffraction at an acoustic frequency of 130 MHz in a 2.0-μm ZnO-film optical waveguide with a strain-controlling film of a 1.5-μm-thick fused-quartz film, as predicted by the theory.
Use of angular-momentum selection rules for laser isotope separation
Authors: Balling L. C. , Wright J. J.
Published: February 2003

A method is proposed for laser separation of certain isotopes with nonzero nuclear spin which relies only on the angular-momentum selection rules for the absorption of circularly polarized light.
Organic solar cells of hydroxy squarylium
Authors: Merritt V. Y. , Hovel H. J.
Published: February 2003

The photovoltaic properties of Schottky barrier solar cells made from thin films (100–1000 Å) of the organic dye hydroxy squarylium have been studied. Amorphous and polycrystalline films, prepared by evaporation and solution casting, have strong absorption over the entire visible spectrum. The highest power conversion efficiency measured under AMO white light was 0.1% (0.14 mW/cm2 input intensity); this decreased to 0.02% at 135 mW/cm2. The decrease in η with intensity is characteristic of organic materials, but is usually much more pronounced. For 8500-Å monochromatic light the quantum efficiency was as high as 2.3% and the conversion efficiency was 0.2% (1 mW/cm2).
Directional acoustic measurements by laser Doppler velocimeters
Authors: Mazumder M. K. , Overbey R. L. , Testerman M. K.
Published: February 2003

Laser Doppler velocimeters (LDV’s) are used as velocity microphones to measure sound pressure level in the range of 90–130 dB, spectral components, and two-point correlation functions for acoustic noise source identification. Close agreement between LDV and microphone data is observed. Directional sensitivity and the ability to measure remotely make LDV’s useful tools for acoustic measurement where placement of any physical probe is difficult or undesirable, as in the diagnosis of jet noise.
Active mode locking of the XeF laser
Authors: Christensen C. P. , Braverman L. W. , Steier W. H. , Wittig C.
Published: February 2003

Active mode locking of the 351-nm XeF excimer laser is reported. Pulse durations of ⩽2 nsec were obtained using acousto-optic gain modulation in a Blumlein-drive laser. The pulsewidth is believed to be limited by the short time duration of the optical gain.
A model of flux pinning by grain boundaries in type-II superconductors
Authors: Pande C. S. , Suenaga M.
Published: February 2003

A relationship between pinning force Fp and grain size D in type-II superconductors derived on the basis of interaction of fluxoids with dislocations forming the grain-boundary walls is reported. While confirming approximately the experimentally observed Fp∝1/D relationship, the theory predicts a peak in Fp at a0/D≃0.2, where a0 is the lattice constant of the flux line lattice.
Simultaneous measurements of current and magnetic field in laser-produced plasmas
Authors: Drouet M. G. , Bolton R. , Saint-Hilaire G. , Kieffer P. , Szili Z. , Pépin H. , Grek B. , Thibaudeau A. , Trépanier K.
Published: February 2003

The current I and the magnetic field B generated during the interaction of focused laser pulses (10.6 μm, 4 J, 1.7 ns or 1.06 μm, 4 J, 20 ns) on a copper target were measured simultaneously as a function of the background pressure in air, N2, He,Ar, and CO2, the results show that I and B are connected, and in addition provide experimental evidence for the diffusion of the magnetic field in laser-produced plasmas.
Preparation of Pb(Zr,Ti)O3 thin films by an electron beam evaporation technique
Authors: Oikawa Masaru , Toda Kohji
Published: February 2003

Thin films of Pb(Zr,Ti)O3 have been fabricated on fused quartz or stainless steel substrates by an electron beam evaporation technique. The quality of the PZT films is examined by the x-ray diffraction technique. Observation of the D-E hysteresis loop has shown the films to be ferroelectric. Dielectric anomaly of the film on a stainless steel substrate has been observed around 340 °C.
Optically pumped GaAs-Ga1−xAlxAs half-ring laser fabricated by liquid-phase epitaxy over chemically etched channels
Authors: Botez Dan , Figueroa Luis , Wang Shyh
Published: February 2003

Half-ring waveguides (5 μm width, 185 μm radius) fabricated by liquid-phase expitaxial growth of Ga1−xAlxAs and GaAs layers over preferentially etched channels in GaAs substrates were made to lase by optical pumping with a N2 laser (λ=3371 Å) at 77 °K. The half-ring lasers had a threshold of about 2×104 W/cm2; a bending loss per radian αc<1.5 cm−1; strong TE polarization; and a well-defined circumferential mode structure: Δλ≃1.07 Å at λ=8280 Å for a 580-μm-long cavity. Straight guides of similar profile to the circular guides were made to lase for comparison. A calculated 0.5-Å mode broadening due to transient heating during the pump laser pulse accounts for the observed lasing spectra.
Backward displacement of waves reflected from an interface having superimposed periodicity
Authors: Breazeale M. A. , Torbett Michael A.
Published: February 2003

An ultrasound beam incident on a liquid-solid interface with superimposed grating is shown to be displaced in a backward direction at certain angles of incidence predicted by the theory of T. Tamir and H. L. Bertoni [J. Opt. Soc. Am. 61, 1397–1413 (1971)]. The analogy between the ultrasonic phenomenon and the corresponding optical phenomenon is cited.
Dislocation climb model in compound semiconductors with zinc blende structure
Authors: Petroff P. M. , Kimerling L. C.
Published: February 2003

A new dislocation climb model is proposed for compound semiconductors with the zinc blende structure. Within the model a supersaturation of only one type of point defect is needed for the dislocation climb process. Consideration of the forces involved suggest that in compound semiconductors grown by liquid-phase epitaxy, interstitial climb is favored. A trail of vacancy defects is then expected to result from the climb process. Experimental observations in support of this model are presented for the case of the defect structures produced during degradation of Ga1−xAlxAs/GaAs (DH) lasers and GaP green-light-emitting diodes.
Coercive force of new Cu-substituted samarium cobalt alloys
Authors: Senno Haruhumi , Tawara Yoshio , Hirota Eiichi
Published: February 2003

It was found that sintered alloys having a composition of approximately z=8 in Sm(Co0.85Fe0.05Cu0.10)z exhibit a high coercive force on the order of 10 kOe, for 5–10-μm average grain size. Magnetization and demagnetization curves showed that the coercive force is controlled by a nucleation process. Attempts were made to achieve a high density without serious grain growth by means of high-pressure isostatic compaction and hot pressing, resulting in 96% of the density and 7-μm average grain size. With this approach, Br=10.3kG, IHc=10.2 kOe, and a maximum energy product of 22.0 MG Oe were achieved.
Applicability of the Fano plot to secondary electron (SE) yield data
Authors: Parikh Mihir , Shimizu Ryuichi
Published: February 2003

SE yield (δ0) data can be interpreted in terms of the Fano plot, thereby yielding a simple formulation of δ0 with respect to the incident electron energy T and a correlation between the mean ionization potential 〈I〉 and a parameter in the Fano plot.
ZnxCd1−xS films for use in heterojunction solar cells
Authors: Burton L. C. , Hench T. L.
Published: February 2003

ZnxCd1−xS films suitable for use in solar cells have been formed by simultaneous evaporating of ZnS and CdS. Lattice parameter and band gap are found to change almost linearly with composition. Electrical resistivity increases from <1 to ≳1010Ω cm as x increases from 0 to 1. Nonseries-resistance-limited ZnxCd1−xS-CuyS photovoltaic cells have exhibited open-circuit voltages greater than 0.7 V, apparently due to a better match between the ZnxCd1−xS and CuyS electron affinities.
Effect of surface stress on the natural frequency of thin crystals
Authors: Gurtin M. E. , Markenscoff X. , Thurston R. N.
Published: February 2003

Within the framework of classical beam theory it is shown that a strain-independent surface stress has no effect on the natural frequency of a thin cantilever beam. Therefore, the experimental results of Lagowski, Gatos, and Sproles must have a different explanation.
Secondary electron energy distributions for gold as excited by C Kα (277 eV) and Al Kα (1487 eV) x rays
Authors: Henke Burton L. , Smith Jerel A. , Attwood David T.
Published: February 2003

The secondary electron energy distributions for a gold photocathode as excited by C Kα (277 eV) and Al Kα (1487 eV) x rays have been measured. The shapes of the energy distributions are essentially the same for these two x-ray photon excitation energies. For thick evaporated gold samples on glass substrates (at 150 °C and 3×10−8 Torr), the secondary electron energy distributions peak at about 1 eV and have a FWHM of about 4 eV. As measured immediately after ion cleaning, the distributions peak at about 2 eV and have a FWHM of about 6.6 eV. Approximately 5 h after ion cleaning, the measured distributions appear as those obtained before ion cleaning. The work function of the evaporated gold photocathode temporarily increases by 1 eV upon ion cleaning.
Laser-induced shock waves in liquids
Authors: Emmony D. C. , Siegrist M. , Kneubühl F. K.
Published: February 2003

High-speed schlieren photography of the interaction of a TEA CO2 laser pulse with the surface of absorbing liquids shows the formation of a complex shock structure in the liquid. The shock structure in liquids with different absorption coefficients at 10.6 μm is compared. In carbon tetrachloride a cylindrical wave is generated in the bulk of the liquid in addition to the hemispherical wave which is formed at the liquid surface. The cylindrical wave leads the hemispherical one, and this separation is interpreted as differential attenuation in the initial phase. This implies a shock velocity above the sound speed within the first 0.5 μs.
New photoelectrochemical display
Authors: Yamana M.
Published: February 2003

A new photoelectrochemical display utilizing the photoinduced reaction of benzyl viologen bromide on a p-type GaP electrode is described. Writing time versus light intensity and other characteristics are given.
Thin-film dye laser with etched cavity
Authors: Hu Chenming , Kim Seihee
Published: February 2003

We describe a thin-film laser with a Fabry-Perot cavity. The cavity is chemically etch into a (100) -cut silicon substrate and filled with rhodamine 6G doped polyurethane. Overfilling of the cavity provides the passage for the output. A nitrogen laser serves as pump source.
Optical waveguide parabolic coupling horns
Authors: Burns W. K. , Milton A. F. , Lee A. B.
Published: February 2003

We propose parabolic-shaped coupling horns to provide adiabatic transition regions between wide- and narrow-channel optical waveguides. The parabolic shape is shown to derive from a simple ray model of channel propagation and is consistent with diffraction theory in the wide-channel limit. An approximate mode dispersion theory is used to convert the criteria into a horn design for indiffused channel waveguides. Experimental horn transmission measurements of nearly 90% are reported for transitions from 25 μm to 8, 6, and 4 μm in Ti:LiNbO3 waveguides at 0.6328 μm.
Radioactive silicon as a marker in thin-film silicide formation
Authors: Pretorius R. , Ramiller C. L. , Lau S. S. , Nicolet M-A.
Published: February 2003

A new technique using radioactive 31Si (half-life =2.62 h), formed in a nuclear reactor, as a marker for studying silicide formation is described. A few hundred angstroms of radioactive silicon is first deposited onto the silicon substrate, followed immediately by the deposition of a few thousand angstroms of the metal. When the sample is heated, a silicide is first formed with the radioactive silicon. Upon further silicide formation, this band of radioactive silicide can move to the surface of the sample if silicide formation takes place by diffusion of the metal or by silicon substitutional and/or vacancy diffusion. However, if the band of radioactive silicide stays at the silicon substrate interface it can be concluded that silicon diffuses by interstitial and/or grain-boundary diffusion. This technique was tested by studying the formation of Ni2Si on 〈100〉 silicon at 330 °C. From a combination of ion-beam sputtering, radioactivity measurement, and Rutherford backscattering it is found that the band of radioactive silicide moves to the surface of the sample during silicide formation. From these results, implanted noble-gas marker studies and the rate dependence of Ni2Si growth on grain size, it is concluded that nickel is the dominant diffusing species during Ni2Si formation, and that it moves by grain-boundary diffusion.
Damage production by high-energy d-Be neutrons in Cu, Nb, and Pt at 4.2 °K
Authors: Roberto J. B. , Klabunde C. E. , Williams J. M. , Coltman R. R. , Saltmarsh M. J. , Fulmer C. B.
Published: February 2003

Electrical resistivity measurements have been used to observe damage production rates for Cu, Nb, and Pt irradiated with high-energy d-Be neutrons at 4.2 °K. The neutrons were generated at the Oak Ridge Isochronous Cyclotron by the reaction of 40-MeV deuterons incident on a thick Be target. The resulting neutron energy spectrum was broadly peaked near 15 MeV. Damage production was proportional to fluence up to 4×1015 n/cm2, and was approximately three times greater than for the same fluence of fission neutrons in these materials. This result is in good agreement with predictions based on damage energy calculations.
Energy threshold effects in the collisionless dissociation of polyatomic molecules by ir laser radiation
Authors: Gower Malcolm C. , Billman Kenneth W.
Published: February 2003

The threshold for collisionless dissociation of SF6, SiF4, and CF2Cl2 by focused CO2 laser radiation has been measured. This threshold is a laser pulse energy effect and, within experimental error, is found to be the same for all three gases. Provided collisions cannot occur during the laser pulse, the degree of dissociation produced depends only on the energy in the pulse, which is consistent with simple adiabatic vibrational heating of the molecules by the laser.
A new acceptor level in indium-doped silicon
Authors: Baron R. , Young M. H. , Neeland J. K. , Marsh O. J.
Published: February 2003

A new acceptor level located 0.111±0.002 eV from the valence band with a peak photoionization cross section of (1.4±0.6) ×10−16 cm2 has been observed in indium-doped silicon. Its presence is revealed both by the low-temperature slope of Hall measurements versus temperature and by the spectral response of the photoconductivity. The concentration of this 0.111-eV level is strongly correlated with the concentration of indium, suggesting that an In complex is responsible for this center.
Conduction and trapping of electrons in highly stressed ultrathin films of thermal SiO2
Authors: Harari Eli
Published: February 2003

Films of thermal SiO2 in the thickness range 30−300 Å were stressed at fields approaching breakdown. Intrinsic breakdown was observed to be preceded by generation of a very high density of electron traps. These traps must be energetically located at least 4 eV below the SiO2 conduction band and may be assocated with broaken Si-O bonds. The ultimate breakdown strength of ultrathin films was found to be (2.8±0.4) ×107 V/cm. The present work suggests a new mechanism to explain intrinsic breakdown in films of thermal SiO2.
Ion-implantation-induced lattice defects in PbTe
Authors: Palmetshofer L. , Heinrich H. , Benka O. , Rescheneder W.
Published: February 2003

Hall-effect and conductivity measurements as well as channeling-effect measurements were used to study the lattice defects induced by ion implantation in thin films of PbTe. The implantation was performed with 300-keV Pb, Te, and Xe ions at room temperature. For the as-implanted samples the Hall-effect measurements gave a constant value for the carrier concentration, independent of the implantation dose. The backscattering measurements showed a continuous increase in the lattice disorder with increasing dose. A model, based on the assumption of an acceptor level above the conduction-band minimum, is proposed to explain this behavior.
A scalable multiatmosphere high-power XeF laser
Authors: Sarjeant W. J. , Alcock A. J. , Leopold K. E.
Published: February 2003

A scalable uv-preionized transverse discharge XeF laser has been operated at pressures up to 5 atm. uv output energies in excess of 250 mJ with a minimum pulse duration of less than 20 ns have been obtained from an active volume of 0.18 liter.
Theory of Mössbauer line broadening due to correlated diffusion in crystals
Authors: Wolf Dieter
Published: February 2003

The line-broadening effect of correlations between successive jumps of a Mössbauer atom is investigated. The ’’encounter model’’ originally developed for nuclear-magnetic-resonance diffusion studies is applied to describe temporal and spatial correlations which may cause significantly smaller linewidths than a random-walk diffusion mechanism. This straightforward analytic generalization of the random-walk results is capable of eliminating some of the earlier discrepancies between diffusion constants determined from radio-tracer and Mössbauer experiments.
A new reflective dichroic liquid-crystal display device
Authors: Cole H. S. , Kashnow R. A.
Published: February 2003

A new reflective dichroic display device is described. The only components include a quarter-wave retarder positioned between an aligned dichroic nematic liquid-crystal display cell and a diffuse metallic reflector. This configuration allows both polarizations of incident light to be absorbed without affecting the polarizer-free high brightness voltage activated state.
Ionic conductivity in Li3N single crystals
Authors: Alpen U. v. , Rabenau A. , Talat G. H.
Published: February 2003

Lithium ionic conductivity of Czochralski-grown Li3N single crystals using electrochemical transport measurements is reported. The highest Li ionic conductivity was found perpendicular to the hexagonal c axis, the anisotropy decreasing from two to one decade between 20 and 200 °C. Ambient Li ionic conductivity parallel to the Li2N planes of the layer structure was found to be σ=10−3 Ω−1 cm−1 with an activation energy of 0.25 eV. These values are comparable with the best data reported for Li β-alumina single crystals.
High-sensitive holographic storage in Ce-doped SBN
Authors: Megumi K. , Kozuka H. , Kobayashi M. , Furuhata Y.
Published: February 2003

High optical sensitivity is observed in 0.1 wt% Ce-doped strontium barium niobate (SBN) crystals in the absence of an external electric field. Only 5–10 mJ/cm2 of incident 0.488-μm radiation is required to produce 10% diffraction efficiency, while the energy to erase holograms from the 80% to its 1/e diffraction efficiency level is 30–40 mJ/cm2 at the same wavelength. Holograms stored in Ce-doped SBN persist at least one month (decay time constant) if kept in the dark at room temperature.
Picosecond optoelectronic switching in GaAs
Authors: Lee Chi H.
Published: February 2003

Picosecond optical pulses are used to switch a GaAs slab in a charged line pulser. The repetition rate of the device is 1 GHz. The effect of the Ridley-Watkins-Hilsum mechanism on the device performance is discussed.
Hard conducting implanted diamond layers
Authors: Hauser J. J. , Patel J. R. , Rodgers J. W.
Published: February 2003

Hard conducting diamond layers were produced by carbon implantation. Above a threshold implantation dose (≃3×1016/cm2), these layers possess the high conductivity of graphite (≃10−2 Ω−1 cm−1) and a hardness intermediate between that of silicon and diamond.
Velocity-field characteristics of Ga1−xInxP1−yAsy quaternary alloys
Authors: Littlejohn M. A. , Hauser J. R. , Glisson T. H.
Published: February 2003

The electron drift-velocity–electric-field relationship has been calculated for the Ga1−xInxP1−yAsy quaternary alloy using the Monte Carlo method. Emphasis has been placed on the compositional range for which the alloy is lattice matched to GaAs and InP. These calculations suggest that this quaternary offers promise as a material for microwave semiconductor devices, including field-effect transistors and transferred electron devices.
Leaky modes effect in spliced graded-index fibers
Authors: Kitayama Kenichi , Ikeda Masahiro
Published: February 2003

In graded-index and step-index fibers, splicing loss was measured under the condition that all the guided modes are equally excited by light-emitting diodes. Measurements were made both for short and long fibers. For a short fiber, the graded-index fiber has a larger splicing tolerance to misalignment than the step-index fiber; while for a long fiber the former was somewhat more sensitive than the latter. This difference can be interpreted as showing that leaky modes, excited by transverse displacement in graded-index fibers, affect transmission loss.
Caustics associated with fiber drawing
Authors: Simpkins P. G. , Dudderar T. D. , McKenna J. , Seery J. B.
Published: February 2003

The formation of caustics in the solidified drawdown zone of samples taken from a laser furnace during the manufacture of fused silica fibers is described. Observations using collimated monochromatic light to axially illuminate the drawdown zone are compared with predictions from ray-tracing algorithms. Variations in the caustic images are shown to be manifestations of changes in the drawdown profile. The agreement between the observed and calculated far-field caustic trajectories is very good.
Attenuation of 10.6-μm beams by electrically initiated laser driven plasmas
Authors: Weiss Paul
Published: February 2003

Measurements have been made of the attenuation of radiation of λ=10.6 μm by a plasma initiated by an electrical spark in air. The light transmission varied from <2% to ≳10% as the input laser energy ranged from 300 mJ to < 0.1 mJ. These results indicate that the spark-initiated plasma acted as a seed plasma for the laser. The trend of increasing attenuation with increasing incident laser energy is promising for use as an isolator in high-power laser systems.
Critical microstructure for ion-implantation gettering effects in silicon
Authors: Geipel H. J. , Tice W. K.
Published: February 2003

The nature of residual ion-implantation damage responsible for gettering deleterious impurities from active semiconductor device regions in Si has been studied. A propensity for dislocations of the type b=1/2 〈110〉 to gather metallic contaminant (e.g., Cu), as compared to Frank partials b=1/3 〈111〉, is established. Transmission electron microscopy and pulsed leakage measurements are used to demonstrate that the density of 1/2 〈110〉 dislocations introduced by Xe implantation greatly influences gettering efficiency.
Picogram detection of cesium in aqueous solution by nonflame atomic fluorescence spectroscopy with dye laser excitation
Authors: Hohimer J. P. , Hargis P. J.
Published: February 2003

The determination of trace cesium in aqueous solution by nonflame atomic fluorescence spectroscopy using dye laser excitation is reported. Using a nonflame atomization system and direct-line fluorescence detection, the limit of detection was found to be 1.2 pg in a 20-pg/ml sample solution.
Reduction of grain boundary recombination in polycrystalline silicon solar cells
Authors: DiStefano T. H. , Cuomo J. J.
Published: February 2003

The possibility of increasing the carrier collection efficiency in polycrystalline silicon by means of a heavily doped region near the grain boundaries is investigated. Phosphorous dopant is preferentially introduced into the grain boundaries of p-type material by a low-temperature diffusion process. A subsequent high-temperature diffusion forms a highly n-doped skin covering each grain. The resulting junction around each grain surface collects electrons which might otherwise recombine at the grain boundaries. This grain boundary doping scheme makes possible an increase in the conversion efficiency of polycrystalline silicon solar cells in which the grain structure is columnar.
Determination of the Be–Auger-electron attenuation length in Be using 160-keV protons
Authors: Needham P. B. , Driscoll T. J. , Powell C. J. , Stein R. J.
Published: February 2003

We report the first results of a method for determining the inelastic attenuation length of low-energy electrons in the surface region of a solid from the yield of characteristic Auger electrons excited by proton bombardment. Samples of evaporated beryllium were bombarded by 160-keV protons, and the attenuation length of 100-eV electrons in Be was determined to be 6.1 Å.
High-resolution topographical images of small metal particles
Authors: Yacamán M. José , Ocaña Z. T.
Published: February 2003

A technique to obtain high-resolution topographical information of particles in the Angstrom-size with a transmission electron microscope is described. This consists of obtaining dark-field images of particles which are tilted away from the Bragg angle and in a N-beam diffracting condition. The effective extinction distance is then substantially reduced and topographical analysis of the small crystallities can be obtained from Pendellösung fringes.