bluuebunny/crossref_metadata_2025 huggingface dataset:
Corona discharge-induced surface chemical effects on II-VI compounds
Authors: Lichtensteiger M. , Webb C.
Published: February 2003

Negative corona charging of CdS and ZnSe leads to a significant change in their surface composition. Utilizing x-ray photoelectron spectroscopy and Auger electron spectroscopy, it is found that the primary interaction occurs between oxygen and group-VI surface atoms. In contrast to other oxidation penomena, no oxygen bonded to group-II surface atoms is detected. The results demonstrate for the first time that the electronic processes involved in electrophotography are accompanied by significant and irreversible chemical reactions of the surface exposed to negative corona discharges.
Raman diffusion profilometry:OH in vitreous SiO2
Authors: Galeener F. L. , Mikkelsen J. C.
Published: February 2003

Techniques are described for using Raman spectroscopy to measure the concentration profiles of impurities that have been diffused into transparent host media. Profiles are presented for the diffusion of water into fused silica. Spatial resolutions of 50 mm for concentrations of OH above 180 ppm (by weight) are demonstrated, and order of magnitude improvements over these values are confidently predicted.
Generation of picosecond pulses from a cavity-dumped synchronously pumped dye laser
Authors: Wirth M. J. , Sanders M. J. , Koskelo A. C.
Published: February 2003

Bandwidth-limited pulses of 2.5 ps in duration are reported for a cavity-dumped synchronously pumped dye laser when saturable absorber is mixed with the laser dye. The pulses are tunable over a 610–640-nm range, and the energy per pulse is in the range of 4–8 nJ.
Embedded epitaxial growth of low-threshold GaInAsP/InP injection lasers
Authors: Chen P. C. , Yu K. L. , Margalit S. , Yariv A.
Published: February 2003

Single-growth liquid-phase embedded epitaxy in the GaInAsP/InP system is described, and a new heterostructure laser is grown using this technique. These lasers exhibit excellent current and optical confinement. Threshold currents as low as 45 mA are achieved for a laser with 4-mm-wide active region.
A classical electron cyclotron quasioptical maser
Authors: Sprangle P. , Vomvoridis J. L. , Manheimer W. M.
Published: February 2003

In this work a new classical electron cyclotron maser oscillator is proposed and analyzed. The configuration utilizes an open-resonator cavity containing a gyrating electron beam, which translates along an external magnetic field directed transverse to the axis of symmetry of the resonator. The nonlinear interaction between the electrons and resonator fields have been analyzed, and an expression for the steady-state efficiency is obtained. For a uniform, external magnetic field our example shows that total efficiencies in excess of 30% can be realized, while appropriately contouring the field increases the efficiency to ∼45%.
A technique for comparing the bulk and surface structure of defects in thin films using the scanning transmission electron microscope.
Authors: Treacy M. M. J. , Krakow W. , Smith D. A. , Trafas G.
Published: February 2003

A technique is described which allows the scanning transmission electron microscope to be operated either in its usual mode to give a transmission image from a thin film, or with a tilted sample to give a low-loss image of the surface. The low-loss image obtained from one surface of a thin-film gold sample is compared with the bright field image of the same area. Microtwins in this film display strong topographic contrast on the single surface studied. From this, it appears that the microtwins are formed by deformation, rather than as growth accidents during the preparation of the sample. It is found advantageous in the low-loss mode to operate with a less steeply tilted sample than heretofore.
Electron spectroscopy of the diamond surface
Authors: Pepper Stephen V.
Published: February 2003

The diamond surface is studied by ionization loss spectroscopy and Auger electron spectroscopy. For surfaces heated to <900 °C, the band gap was found to be devoid of empty states in the absence of electron beam effects. The incident electron beam generates empty states in the band gap and loss of structure in the valence band for these surfaces. A cross section of 1.4×10−19 cm2 was obtained for this effect. For surfaces heated to ≳900 °C the spectra were identical to those from surfaces modified by the electron beam. The diamond surface undergoes a thermal conversion in its electronic structure at ∼900 °C.
Effect of growth temperature on the photoluminescent spectra from Sn-doped Ga1−xAlxAs grown by molecular beam epitaxy
Authors: Swaminathan V. , Tsang W. T.
Published: February 2003

We have investigated the photoluminescence properties of Sn-doped Ga1−xAlxAs (x∼0.24–0.29) grown by molecular beam epitaxy as a function of growth temperature in the range 400–675 °C. The photoluminescence intensity of the broad band at 300 K and that of the edge emission bands at 5.5 K increases with increasing growth temperature. The 5.5-K emission spectra from samples grown below 565 °C show several weak and broad emission bands well separated from the band edge, which are attributed to Sn-related complexes. The density of these complexes decreases at growth temperatures above 565 °C resulting in drastic improvement in the optical quality of the wafers.
Photovoltaic detectors in SnS produced by Sb+ ion implantation
Authors: Trbojevic D. , Nikolic P. M. , Perovic B. , Cvekic V.
Published: February 2003

N p junction photovoltaic detectors in the p-type single-crystal SnS have been produced by Sb+ ion implantation. Current-voltage and capacitance-voltage characteristics have been measured at 77 and 295 K. At 77 K, diodes had zero-bias resistance area products of 1.5×103 W cm2. The spectral response has been measured at 77 and 295 K. At 295 K, the peak responsivity was at a wavelength of 0.76 mm. At 77 K, the peak detectivity, which occurred at 0.62 mm, was 1.3×1011 cm Hz1/2 W−1 with a peak quantum efficiency of 44%.
Pyroelectric behavior of LiNbO3 at low temperatures
Authors: Vieira S.
Published: February 2003

A large enhancement of the ratio between the proelectric coefficient r and the heat capacity C is obtained for LiNbO3 for T<10 K. This suggests that this material could be a good infrared detector at low temperatures.
Temperature dependence of threshold of InGaAsP/InP double-heterostructure lasers and Auger recombination
Authors: Dutta N. K. , Nelson R. J.
Published: February 2003

We have calculated the nonradiative Auger recombination rate as a function of temperature in InGaAsP. Inclusion of this process can explain the observed temperature dependence of threshold and carrier lifetime of both the 1.3- and 1.55-mm InGaAsP double-heterostructure lasers. The threshold calculations are carried out using the Halperin-Lax-Kane band model, Stern’s matrix element, and Beattie-Landsberg theory of Auger recombination. Evidence of the Auger recombination is provided by a sublinearity of the spontaneous emission as a function of injection current.
Infrared sensitive organic photoconductor
Authors: Grammatica S. , Mort J.
Published: February 2003

Photoconductivity and basic electrophotographic photoreceptor parameters are reported on a composite photoreceptor structure in which the sensitizing photoconductive layer consists of vanadyl phthalocyanine. The results indicate useful electrophotographic performance with a photogeneration efficiency of ∼0.2 at 45 V/mm extending from 4000 to 9000 Å. This covers the spectral emission range of GaAs solid-state lasers and is an excellent match to the solar spectrum. E;81 72.40.+w 72.20.Jv, 72.80.Le
Transmission electron microscopy and ion-channeling studies of heteroepitaxial Ge1−xSix films produced by transient heating
Authors: Tsaur Bor-Yeu , Fan John C. C. , Sheng T. T.
Published: February 2003

The crystal quality of heteroepitaxial Ge1−xSix films produced by transient heating of Ge-coated Si substrates has been studied by using transmission electron microscopy (TEM) and 4He+-ion channeling. The TEM observations reveal a high density of misfit dislocations near the alloy-Si interface, with a much lower density of inclined dislocations propagating up toward the surface. The total projected length of dislocation lines per unit area has been determined as a function of depth by analysis of TEM micrographs and ion channeling spectra for a film with uniform composition of Ge0.72Si0.28 between the surface and the interfacial region. The results obtained from the two types of data are in good agreement.
Determination of laser damage thresholds by comparison with an absolute laser damage standard
Authors: Milam D. , Willis J. B. , Rainer F. , Wirtenson G. R.
Published: February 2003

Absolute laser-damage thresholds can be rapidly measured by comparison with an absolute laser-damage standard. Multiple-layer TiO2/SiO2 antireflection films on BK-7 glass were found to be the best available damage standards for use at 1064 nm.
Temperature sensitivity of prism coupling to lithium niobate optical waveguides
Authors: Holman R. L. , Cressman P. J.
Published: February 2003

Experiments characterizing the temperature sensitivity of tapered-gap prism coupling to in- and out-diffused lithium niobate optical waveguides are reported. Reduction in coupling efficiency with changes in ambient temperature are shown to be related primarily to the temperature dependence of lithium niobate’s extraordinary refractive index. Optimum coupling efficiency is shown to be recoverable by adjustment of only the prism coupling angle. Several methods are discussed for dealing with this problem.
Realization of temperature-compensated GaAs surface acoustic wave delay lines
Authors: Grudkowski T. W. , Gilden M.
Published: February 2003

Compensation for the first-order temperature coefficient of phase delay (TCD) of GaAs surface acoustic wave delay lines has been experimentally achieved using a two-layer Au/SiO2 film coating. The negative TCD of SiO2 provides temperature compensation, while the mass loading effect of the gold layer provides nonleaky Rayleigh wave propagation.
A new electrical breakdown phenomenon in gas-filled insulating bulbs
Authors: Friedmann D. , Curzon F. L. , Young J.
Published: February 2003

A new electrical breakdown effect is reported in which optical pulses are produced by applying an alternating field of low frequency fA (1 Hz< fA < 600 Hz) to a gas-filled glass bulb. The mean number of pulses in the period f−1A depends linearly on the field amplitude, and the minimum voltage required across the bulb diameter to maintain the effect satisfies Paschen’s law. In a typical case, a 25-mm-diam bulb filled with neon at a pressure of 1–10 Torr flashed at a frequency of 120 Hz when subjected to a 60 Hz field of 15 kV/m rms. The results are explained by a model in which each breakdown resets the field inside the bulb to zero, thereby quenching further optical emission until the next breakdown occurs.
A polyacetylene:aluminum photodiode
Authors: Weinberger B. R. , Gau S. C. , Kiss Z.
Published: February 2003

The fabrication of a 1-cm2 (CH)x:Al Schottky photodiode with junction internal conversion efficiency of 0.30% and quantum efficiency approaching unity (hn≳2.8 eV) is reported. Device characteristics are presented. The effect of oxygen contamination is also discussed.
An efficient low-energy electron-spin-polarization analyzer
Authors: Erbudak M. , Müller N.
Published: February 2003

The spin-orbit coupling in the scattering of electrons at the surface of a gold crystal induces a spin-dependent absorption of electrons. A huge spin dependence of the absorbed current is observed, which promises the realization of an electron-spin-polarization analyzer with an efficiency of over 10−2.
An electron spin polarization detector: Spin-dependent absorption of a polarized electron beam
Authors: Celotta R. J. , Pierce D. T. , Siegmann H. C. , Unguris J.
Published: February 2003

The exchange interaction and the spin-orbit interaction are observed to cause a spin dependence of the absorption of a polarized electron beam in the amorphous ferromagnet Ni40Fe40B20 and a W(100) single crystal respectively. The enhancement of the spin dependence, near the energy where the secondary electron yield is unity, is shown to provide a simple efficient detector of spin polarization.
cw narrow beam (AlGa)As multiquantum-well heterostructure lasers grown by molecular beam epitaxy
Authors: Tsang W. T. , Hartman R. L.
Published: February 2003

Proton-bombarded stripe-geometry (12×380 mm) lasers have been fabricated from multiquantum-well (MQW) heterostructure wafers grown by molecular beam epitaxy (MBE). cw current thresholds as low as 76 mA were obtained in spite of the reduced optical confinement factor G in these lasers. Such values are comparable with the lowest values obtained from similar stripe-geometry proton-bombarded double-heterostructure (DH) lasers. There also appears to be an improvement in the linearity and ’’tracking’’ of the output powers from the end mirrors in these MQW lasers over DH lasers using the same proton-irradiated stripe-geometry for current injection. Such improvements are results of a better lateral mode stabilization with injection currents. Significant beam width reduction in the direction perpendicular to the junction plane was obtained. The half-power full-width q⊥ as narrow as 25° was obtained. For the stripe-geometry lasers fabricated from some MQW wafers, the characteristic temperature T0 in the current threshold-temperature dependence can be as high as 293 °C in the temperature range of 10–70 °C.
Large-Stokes-shift stimulated four-photon mixing in optical fibers
Authors: Lin Chinlon , Bösch M. A.
Published: February 2003

We report the first observation of large-freguency-shift (2000 to over 4000 cm−1) phase-matched stimulated four-photon mixing in low-mode-number silica fibers and discuss the use of this process for efficient frequency conversion in the visible, the near IR, and the near UV region of the spectrum.
Photo-optical switching devices by amorphous As2S3 waveguides
Authors: Tanaka Keiji , Odajima Akira
Published: February 2003

A novel optical device based on a ’’dynamical refractive-index change’’ in an amorphous As2S3 film is constructed. In this device coupling of a red light beam into the thin-film waveguide with a prism coupler is controlled by illuminating blue light. A switching time of about 10 s and an on/off ratio as high as 6/1 have been achieved. Further, this device can be operated as a photo-optical switch having a storage function by changing the intensity of the light beams.
Photoplastic effect in anthracene crystals
Authors: Kojima Kenichi
Published: February 2003

The photoplastic effect is observed in anthracene single crystals under illumination with near-ultraviolet light. The overall features of the action spectrum of hardening bear a close resemblance to the absorption spectrum. The maximum hardening due to illumination reaches as much as 10% of yield stress at 120 W/m2.
Contact reaction between Si and rare earth metals
Authors: Thompson R. D. , Tsaur B. Y. , Tu K. N.
Published: February 2003

Reactions between Si and thin films of rare-earth metals (Gd, Dy, Ho, Er, plus Y and La) in the temperature range of 275–900 °C have been studied by using x-ray diffraction and ion backscattering spectrometry. The disilicides of these metals are apparently the first phase to form, forming rapidly within a narrow temperature range (325–400 °C), and are stable up to 900 °C. The growth does not follow a layered growth mode.
Influence of the electric field on collection efficiencies of solar cells
Authors: Böer Karl W.
Published: February 2003

Solar cells which show a field-dependent collection efficiency in the current saturation range must exhibit a field-dependent carrier redistribution over localized states within the junction. Such redistribution may be caused by ″field quenching″ which is a well-known effect in photoconductive CdS, providing for field saturation and consequently causing the short-circuit current to saturate before the emitter limit is reached.
Tristability in the electric-field-induced phase transformation of liquid-crystal films
Authors: Lin-Hendel Catherin G.
Published: February 2003

A tristability is observed in the electric-field-induced liquid-crystal (LC) cholesteric-to-nematic phase transformation. The stable memory associated with the tristability has a potential application to display devices. The N-C relaxation characteristics, which determine the tristability, are found to be related to the ratio of LC-film thickness to pitch length.
Low Schottky barrier of rare-earth silicide on n-Si
Authors: Tu K. N. , Thompson R. D. , Tsaur B. Y.
Published: February 2003

Disilicide of rare-earth metals (Dy, Er, Ho, and Gd) and Y have been formed by reacting the metallic film on both n- and p-type silicons at around 350 °C for Schottky-barrier height measurement using I-V technique. A passivation coating of W, or Pt, or both was used to prevent the rare earth from oxidation. Schottky-barrier heights of about 0.4 eV on n-Si and 0.7 eV on p-Si were determined.
Schottky barrier heights of molecular beam epitaxial metal-AlGaAs structures
Authors: Okamoto K. , Wood C. E. C. , Eastman L. F.
Published: February 2003

Epitaxial Al Schottky barriers were grown on molecular beam epitaxy AlxGa1−xAs layers without exposure to air. Al is deposited on As-rich surfaces of AlxGa1−xAs form AlAs interfacial layers modifying the intrinsic Shottky barrier height. The difference between In-AlGaAs and Al-AlGaAs barrier heights agree well with their work function difference. Shottky barriers prepared on AlGaAs surfaces with the lowest As-coverage obey the common anion rule in the region x⩽0.3. Above this value oxygen-related elements appear to dominate.
High-through-put, high-yield, and highly-reproducible (AlGa)As double-heterostructure laser wafers grown by molecular beam epitaxy
Authors: Tsang W. T.
Published: February 2003

It is shown that high-through-put, high-yield molecular beam epitaxy, and highly reproducible (AlGa)As double-heterostructure (DH) laser wafers can be grown by molecular beam epitaxy (MBE) with properly designed multichamber MBE systems. This is demonstrated by growing two series of (AlGa)As DH laser wafers and measuring their broad-area threshold current density Jth distributions across the wafers (3.5 cm diameter). The first series consists of four different wafers grown consecutively at growth rates of 2.9, 4.2, 7.4, and 9.5 mm/h. The results show that the Jth’s are not affected by accelerated growth rates. In the second series, four DH laser wafers having the same layer structures were grown under the same conditions without interruption at 11.5 mm/h. The results show that even at such high growth rates the qualities of the DH laser wafers are still highly reproducible. The low-averaged Jth’s (∼700 A/cm2) of the present DH wafers in both series also show that the material and heterojunction qualities of these wafers are as good as those previously grown at lower growth rates (∼1.5 mm/h). The half-peak full-width of the Jth distributions across an area of 3-cm width of the wafers (3.5 cm diameter) are about 50–60 A/cm2. Such narrow range of distributions ensures high device yield.
Brightness and contrast ratio of black-and-white reflective dichroic liquid-crystal displays
Authors: Aftergut Siegfried , Cole Herbert S.
Published: February 2003

Reflectance and contrast ratio of a black liquid-crystal display made from a solution of dichroic dyes in a cholesteric host were measured as function of incidence angle and liquid-crystal layer thickness. The experimental data were in reasonable agreement with theory.
Cerenkov radiation in dielectric-lined waveguides
Authors: Felch K. L. , Busby K. O. , Layman R. W. , Kapilow D. , Walsh J. E.
Published: February 2003

Using a dielectric-lined waveguide in combination with a relativistic electron beam, we are able to produce 1 kW of Cerenkov microwave radiation. We have observed the dependence of the output microwave frequency on the beam voltage. In addition, we have detected microwave radiation in excess of 150 GHz, corresponding to higher-order mode interaction.
Monoenergetic Cs+ source with increased brightness
Authors: Dreyfus R. W.
Published: February 2003

Sequential absorption of two laser photons converts a Cs atomic beam into a ’’cold’’ Cs+ ion beam, i.e., a beam with minimal random kinetic energy [Appl. Phys. Lett. 36, 495 (1980)]. Improvements have now increased the spectral brightness by 2.7×104 times, i.e., to 2.7 A/cm2 sr eV, and have thereby made this source practical for ion microscopy and similar experiments requiring high-brightness beams with minimal energy spread.
Low-noise tunnel junction dc SQUID’s
Authors: Cromar M. W. , Carelli P.
Published: February 2003

We present the results of an investigation of thin-film dc super conducting quantum interference device (SQUID’s) with very high energy resolution. The SQUID’s were fabricated using integrated-circuit techniques appropriate for superconducting devices. A weakly coupled SQUID with very low inductance (1 pH) had an intrinsic energy sensitivity 6×10−34 J/Hz = 0.9 h. A well-coupled SQUID (coupling constant α = 0.43) had an energy sensitivity referred to the input coil of 4.7×10−32 J/Hz = 71 h.
Pressure dependence of the energy levels of irradiation-induced defects in GaAs
Authors: Wallis R. H. , Zylbersztejn A. , Besson J. M.
Published: February 2003

We have measured the pressure dependence of the energy levels of the deep traps E2, E3, and E4 produced by irradiation of GaAs with 1-MeV electrons. All three traps have pressure coefficients which are an appreciable fraction of that of the direct gap, with values relative to the bottom of the conduction band of 8.8, 13.5, and 10.5 meV/kbar, respectively, being obtained. We conclude that the previous identification of the E3 level as being the isolated Ga vacancy is far from certain.
Single-mode positive-index guided cw constricted double-heterojunction large-optical-cavity AlGaAs lasers with low threshold-current temperature sensitivity
Authors: Botez D. , Connolly J. C.
Published: February 2003

A new type of constricted double-heterojunction large-optical-cavity (CDH-LOC) laser is obtained by growing relatively thick (0.2–0.3 μm) convex-lens-shaped active layers above concave-lens-shaped guide layers. By using the effective-index method it is shown that the resultant lateral waveguide is of the positive-index type. The device reproducibly provides single-mode cw laser operation (10 mW cw and 20 mW pulsed) in narrow single-lobed beams (ϑ∥ = 8°; ϑ⊥ = 30°), and displays very high threshold-current temperature coefficients, (T0≅135 °C, pulsed and cw) for LOC-type structures. The cw threshold currents and differential quantum efficiencies (one facet) are between 60–70 mA and 30–35%, respectively. The performance of the ’’positive-index’’ CDH-LOC laser is discussed in view of results from the previously reported ’’leaky-cavity’’ CDH-LOC laser.
A large linear electro-optic effect in a polar organic crystal 2-methyl-4-nitroaniline
Authors: Lipscomb G. F. , Garito A. F. , Narang R. S.
Published: February 2003

The dc linear electro-optic effect and the x-ray crystal structure of the organic molecular solid 2-methyl-4-nitroaniline (MNA) have been studied. One polar orientation was found to have an exceptionally large figure of merit for electro-optic phase retardation ( 1/2 (n13r11−n33r31) = 270±50×10−12 m/V), which is traced to a single, large component of the corresponding microscopic molecular susceptibility. Comparison with second-harmonic generation data demonstrates that the liner electro-optic effect in MNA is primarily electronic in nature.
The effect of atomic hydrogen passivation on polycrystalline silicon epitaxial solar cells
Authors: Robinson P. H. , D’Aiello R. V.
Published: February 2003

Solar cells fabricated in 20-μm-thick epitaxial layers grown on p+ polycrystalline upgraded metallurgical-grade silicon substrates were subjected to atomic hydrogen passivation at 400 °C for 3 1/2 h. The measured solar-cell characteristics show marked increases in open-circuit voltage, fill factor, and efficiency after hydrogenation.
Kinetics and mechanism of amorphous hydrogenated silicon growth by homogeneous chemical vapor deposition
Authors: Scott B. A. , Plecenik R. M. , Simonyi E. E.
Published: February 2003

A new method of amorphous hydrogenated silicon (a-Si:H) chemical vapor deposition is presented in which SiH4 is homogeneously decomposed at high temperature and pressure to produce films on low-temperature substrates having up to 30-at. % H and properties very similar to plasma-deposited material. Kinetic studies provide a film growth activation energy of 54 kcal/mole, confirming that SiH2 is the primary gas phase intermediate. A mechanism based on SiH2 chemistry is presented to account for the rapid surface reactions leading to a-Si:H growth and its possible relevance to the plasma deposition process is emphasized.
Photoelectrochemical etching of p-GaAs
Authors: Ostermayer F. W. , Kohl P. A.
Published: February 2003

A photoelectrochemical method for etching p-GaAs is reported. The method overcomes the apparent stability of GaAs to reductive decomposition by switching the potential of the p-GaAs between a value at which photogenerated electrons reduce the surface to Ga and As3−, and a more positive value at which the majority carrier holes oxidize the Ga to Ga3+. Etching has been observed in a variety of acidic and basic solutions in which As3− and Ga3+ are soluble. With a 633-nm He-Ne laser beam having a peak intensity of 0.75 W cm−2, a maximum etch rate of 1300 Å/min has been obtained in a 0.1-M H2SO4–0.1-M NaSCN solution. The rate of etching appears to be limited by the rate of dissolution and transport of the products away from the surface. The method is potentially useful for producing anisotropic etching in a variety of GaAs devices.
Potential material for narrow-band detectors in the visible range
Authors: Joshi N. V. , Martin J. , Quintero P.
Published: February 2003

The photoconductivity spectrum of the magnetic semiconductor Cd1−xMnxTe has been studied at 300 K for various compositions of Mn. It has been found that this system is photosensitive and shows a remarkably sharp peak in the photoresponse curve for each composition. The half-widths for some of them are as small as 100 Å. Spectral position varies from 0.68 to 0.49 μ as X varies form 0.3 to 0.7. The sharp photoresponse suggests that Cd1−xMnxTe is a potential candidate as a narrow-band detector in the visible range.
Influence of growth temperature on Be incorporation in molecular beam epitaxy GaAs epilayers
Authors: Duhamel N. , Henoc P. , Alexandre F. , Rao E. V. K.
Published: February 2003

Photoluminescence investigation of several Be-doped molecular beam epitaxy GaAs epilayers (including post-epi-growth-annealed layers) revealed the presence of nonradiative recombination centers having the following properties. In low-temperature (550 °C)-grown layers their concentration is found to increase with Be acceptor concentration, while high-temperature (640 °C)-grown layers exhibited only a low concentration of these centers. Transmission electron microscope measurements on these layers showed the presence of extrinsic stacking faults involving interstitial atoms. Since this stacking faults density is also found to increase with doping level, we tentatively conclude that Be interstitial atoms are most likely participating in the formation of nonradiative centers.
Charged wall formation mechanism in ion-implanted contiguous disk bubble devices
Authors: Hidaka Y. , Matsutera H.
Published: February 2003

Charged wall formation mechanism at the contiguous disk bubble propagation pattern edges are investigated by using various kinds of garnet epitaxial layers with in-plane magnetization. Charged walls were observed only in in-plane magnetization layer with stress-induced negative uniaxial anistropy energy. A model is proposed to explain the charged wall formation mechanism in ion-implanted contiguous disk drive layer. It is suggested that, in order for charged walls to be held at the pattern edge, compressive lattice stress relief at the pattern edge is necessary, when the magnetostriction constant λ111 is negative.
Zinc phosphide-zinc oxide heterojunction solar cells
Authors: Nayar P. S. , Catalano A.
Published: February 2003

The photovoltaic properties of p-Zn3P2/n-ZnO heterojunction solar cells prepared by sputter deposition of ZnO on Zn3P2 substrates are reported. An active-area power conversion efficiency of ∼2% has been obtained. The experimental results are discussed on the basis of an interface recombination model. The interface plays a significant role in determining the performance of the device.
Unsuccessful attempt to observe unrectified noise and nonlinear behavior in various resistances
Authors: Kumar A. , Goldburg W. I.
Published: February 2003

A number of experiments report that high-frequency currents produce low-frequency 1/f noise in carbon resistors. We see no evidence of this ’’unrectified noise’’ in carbon resistors and a conducting fluid mixture.
Repetitive pulsating stripe geometry GaAlAs double-heterostructure lasers with a stripe by a shallow Zn diffusion
Authors: Hanamitsu K. , Fujiwara T. , Takusagawa M.
Published: February 2003

We have fabricated a repetitively pulsating stripe geometry GaAlAs double-heterostructure laser with a stripe by a shallow Zn-diffusion into n-GaAs top layer, generating high-power fundamental transverse-mode optical pulse trains. Spatially inhomogeneous current injection for exciting pulsations is achieved by a nonuniform breakover in space-charge region under the Zn-diffused stripe. These generated optical pulses have a peak power of more than 10 mW, a width of 0.4 ns, and a repetition frequency of 200 MHz–1 GHz.
Band-to-band Auger recombination in InGaAsP lasers
Authors: Sugimura Akira
Published: February 2003

Band-to-band Auger recombination in InGaAsP lasers is studied theoretically. An approximation method for the calculation is derived and the Auger coefficient is given explicitly as a function of injected carrier density. Auger lifetime and the threshold current density for the InGaAsP laser are calculated with good agreement with reported experimental results. This shows that Auger recombination is one of the dominant factors which causes the poor temperature characteristics of InGaAsP laser threshold current.
12.8-μm NH3 laser emission with 40–60% power conversion and up to 28% energy conversion efficiency
Authors: Gupta P. K. , Kar A. K. , Taghizadeh M. R. , Harrison R. G.
Published: February 2003

The characteristics of an extremely efficient 12.8-μm NH3 laser utilizing a rather simple and versatile optical pumping arrangement are reported. CO2 laser pump to NH3 laser energy conversion efficiencies of up to 28%, very close to the theoretical limit of 33% for this system, and power conversion efficiencies of 40–60% have been achieved. Both the efficiencies are considerably higher than the best reported to date for this emission.
A tunable, ultrahigh-spectral-brightness ArF* excimer laser source
Authors: Egger H. , Srinivasan T. , Hohla K. , Scheingraber H. , Vidal C. R. , Pummer H. , Rhodes C. K.
Published: February 2003

An extremely high spectral-brightness ArF* 193-nm excimer source with the following output pulse characteristics is described: ∼30-mJ pulse energy, ∼5-nsec pulse duration, spectral width less than 260 MHz, absolute frequency control to within 1.8 GHz, ∼5×15-μrad beam divergence, and repetition rate up to 10 Hz. Within the uncertainty of measurement, the spectral width of the output radiation is Fourier transform limited and the beam divergence corresponds to the diffraction limit of the radiating aperture.
Scaling studies in field reversal experiments
Authors: Lipson J. , Armstrong W. T. , Cochrane J. C. , McKenna K. F. , Sherwood E. G. , Tuszewski M. , Hamasaki S.
Published: February 2003

The stable period of field-reversed configurations, defined by the onset of the rotational n = 2 instability, is observed to scale with R2/ ρi over a new, wider range of experimental conditions, where R is the major radius and ρi is the ion gyro-radius indexed to the external field. The scaling factor is approximately 6.0×10−7 sec cm−1 over a range of R2/ ρi from 18 to ∼100 cm in which 1/ ρi varied from 1 to 5 cm−1 and R varied by approximately 30%. In a complimentary study, the stable period was observed to be independent of Ti over a range of 200–1200 eV when R2/ ρi was held approximately constant. The theoretical correlation of the stable period with the particle containment time, and hence with R2/ ρi, are discussed.
Elemental arsenic in native oxide films on AlxGa1−xAs
Authors: Schwartz G. P. , Dutt B. V. , Gualtieri G. J.
Published: February 2003

Surface reflection Raman scattering has been used to detect the presence of elemental arsenic in native oxide films grown on epitaxial (100) AlxGa1−xAs layers. Oxide films formed either by direct thermal oxidation in air at 450 °C or by electrochemical anodization followed by thermal aging (450 °C, in vacuo) were both found to contain elemental arsenic. Anodic films which were not subjected to a heat treatment showed no evidence for elemental arsenic inclusions within the detection limits of the technique. These observations are consistent with the occurrence of a thermally induced interfacial reaction involving As2O3 in the anodic film and the substrate.
X-ray imaging with a charge-coupled device fabricated on a high-resistivity silicon substrate
Authors: Peckerar M. C. , McCann D. H. , Yu Leepo
Published: February 2003

In this letter results are reported on x-ray imaging experiments performed with a buried channel charge-coupled-device line array optimized for photon sensing in the 1–10-keV range. Optimization was achieved by increasing the depletion depth of the device to 254 μ. A near-unity detector quantum efficiency (98%) was thus achieved. There was no observable image blurring due to diffusive spreading of signal charge as a result of the field-assisted transport to the well minima.
Thin-film gallium arsenide homojunction solar cells
Authors: Chu Shirley S. , Chu T. L. , Zhang F. S. , Book L. , Yu J. M.
Published: February 2003

Thin-film homojunction gallium arsenide solar cells of p+/n/n+ configuration have been deposited on tungsten coated graphic substrates by the reaction of gallium, hydrogen chloride, and arsine containing appropriate dopants. Solar cells of 8-cm2 area with an AM1 efficiency of about 7% have been prepared for the first time. The solar cells are characterized by dark and illuminated current-voltage and quantum efficiency measurements.
Dynamical x-ray reflection at terraces in epitaxial layers
Authors: Chang Shih-Lin
Published: February 2003

Terrace formation in semiconductor epitaxial layers has been postulated to cause lattice bending, which ought to be observable by x-ray diffraction. Consideration of dynamical effects of x-ray reflection, both at the terraces and from a distorted crystal lattice, shows that diffraction effects by far outweigh the effects of lattice bending. For a given liquid phase epitaxial GaAs layer on a GaAs substrate, the lattice bending is estimated to be less than 10−5 rad.
Electron tunneling in Si-SiO2-Al structures: A comparison between 〈100〉 oriented and 〈111〉 oriented Si
Authors: Krieger Gadi , Swanson Richard M.
Published: February 2003

Si-SiO2-Al capacitors were fabricated on both 〈100〉 and 〈111〉 oriented Si. The electron tunneling current from the Si accumulation layer was measured in the Fowler–Nordheim region. Comparing the current versus electric field for both crystal orientations, tunneling current is appreciably higher in 〈100〉 oriented than in 〈111〉 oriented capacitors. An explanation is suggested based on the conservation of transverse crystal momentum. The result implies that metal-oxide-semiconductor transistors fabricated on 〈111〉 oriented Si might be less susceptible to oxide injected charge instabilities than those fabricated on 〈100〉 oriented Si.
Autosynchronized pulse generation at multiple wavelengths
Authors: Rabinowitz P. , Perry B. , Gnauck A.
Published: February 2003

Efficient autosynchronization of Raman scattered Stokes pulses of different wavelengths is obtained from a hydrogen filled multiple pass cell. The phenomenon is initiated by colinear four-wave mixing and develops through Raman scattering at ray crossings within the cell structure.
Deterministic passive mode locking of solid-state lasers
Authors: Martínez Oscar Eduardo , Spinelli Luis Alfonso
Published: February 2003

An additional passive modulation is inserted in the cavity of a passive mode-locked Nd:glass laser in order to provide the conditions for a complete selectivity of the system. A rate equation approach shows that a stationary condition is reached in which only one pulse of the original fluctuation pattern is left. Computed simulations and experimental results are also shown confirming the theoretical predictions.
Photoacoustic microscopy with a new modulation technique
Authors: Quimby R. S.
Published: February 2003

A new type of photoacoustic microscopy is described in which the beam position, rather than the beam intensity, is modulated. It is demonstrated experimentally that the new technique provides greater detail and contrast than conventional photoacoustic microscopy.
Compression of an intense space-charge-neutral ion beam by an axial magnetic field
Authors: Robertson Scott
Published: February 2003

An intense, space-charge-neutral beam of protons (150 kV, 15 A/cm2) has been compressed from an initial diameter of 15 cm to a final diameter of 5 cm by propagating it along a magnetic field increasing from zero to 700 G in a distance of 55 cm. At the field maximum, the beam intensity is increased by a factor of 4 over the value with no field. When viewed from the beam frame, the experiment is analogous to a theta pinch with an applied field whose time derivative is v(dB/dx), where v is the beam velocity and dB/dx is the magnetic gradient. The surface of the beam moves radially inward at approximately the velocity predicted by the snowplow model.
Ion beam range shortening and the possibility of thermal instability
Authors: Slutz Stephen A. , Mehlhorn Thomas A.
Published: February 2003

The range of an ion can be decreased when the deposition material is heated because of the greater stopping power of free electrons over bound electrons. This suggests the possibility that a medium heated by an intense ion beam might suffer a thermal instability. It is shown that such an instability should not be important over the regimes of interest for ion beam fusion.
The effect of cavity length on picosecond pulse generation with highly rf modulated AlGaAs double heterostructure lasers
Authors: Aspin G. J. , Carroll J. E. , Plumb R. G.
Published: February 2003

We report the generation of picosecond pulses with oxide-isolated-stripe, double heterostructure GaAlAs laser diodes of varying lengths. A pulse width of 15 ps at a repetition frequency of 1 GHz is achieved with a 60-μm-long device. The experiments indicate a linear relation between pulse width and laser length.
Optical Ramsey fringes: Effect of velocity averaging on fringe shape and position
Authors: Bava G. P. , De Marchi A.
Published: February 2003

A theoretical analysis of Ramsey fringes produced by the interaction of a molecular beam and a three-zones electromagnetic resonator is reported. After averaging over the longitudinal velocity distribution of the particles, the relation between the fringe envelope width and the velocity distribution width is discussed. If the second-order Doppler shift is introduced, the fringe envelope displacement is found to be of the same amount expected for the second-order Doppler effect, but in the opposite direction. This analysis can be of some interest for the discussion of the performance of beam frequency standards in the near optical region.
Molecular beam epitaxial growth of high structural perfection, heteroepitaxial CdTe films on InSb (001)
Authors: Farrow R. F. C. , Jones G. R. , Williams G. M. , Young I. M.
Published: February 2003

Heteroepitaxial films on CdTe have been grown by molecular beam epitaxy (MBE) on InSb (001) orientation substrates at growth temperatures ≲220 °C. The structural perfection of these films has been explored by double crystal x-ray diffraction techniques, which reveal that films of ∼1 μm thick grown at 150 and 220 °C are free of low-angle grain boundaries and are exactly lattice matched to the InSb substrate. The lattice parameter mismatch is accommodated by misfit elastic strain.
High-efficiency high-power butt coupling of single-mode diode lasers to indiffused LiNbO3 optical waveguides
Authors: Hammer J. M. , Botez D. , Neil C. C. , Connolly J. C.
Published: February 2003

We have butt coupled 13-mW cw and 27-mW (5-μs-long pulses, 5% duty cycle) optical power into a single mode Ti-LiNbO3 optical waveguide by using single-mode diode lasers at λ = 0.84 μm. Coupling efficiencies greater than 68% were observed. These are the highest diode-laser powers coupled by any means into the technologically important class of LiNbO3 optical waveguides. Our observations support the theory of butt coupling between injection lasers and waveguides at hitherto unavailable power levels and efficiencies. The light coupled into the waveguide has a substantially reduced incoherent power level when compared to that emitted by the laser.
Threshold behavior of Si films melted with a cw yttrium aluminum garnet laser
Authors: Lemons R. A. , Bösch M. A.
Published: February 2003

When polycrystalline silicon films deposited on fused quartz are heated with 1.06 μm radiation from a cw yttrium aluminum garnet laser, melting occurs at a sharp threshold of laser power and time. This threshold behavior is interpreted as a thermal runaway phenomenon. The initially weak absorption of the laser beam slowly heats the film thereby increasing the absorption. This positive feedback results in abrupt melting after a substantial delay. A one-dimensional analysis of the heat flow predicts the essential features of this effect.
Optical properties and water absorption of anodically grown native oxides on InP
Authors: Studna A. A. , Gualtieri G. J.
Published: February 2003

The optical properties from 1.5–6.0 eV and the absorption of H2O for an electrochemically grown anodic oxide on InP 〈100〉 have been measured. The oxide thickness was observed to increase by roughly 40% and the refractive index to decrease by 7% in the range of 2 eV when exposed to an ambient containing H2O. The oxide film was also heated to a temperature of 200 °C. The results indicate a change in the chemical composition of the oxide when exposed to either an ambient containing water or an elevated temperature.
Solar cells made by laser-induced diffusion directly from phosphine gas
Authors: Turner G. B. , Tarrant D. , Pollock G. , Pressley R. , Press R.
Published: February 2003

A new method for making p-n junctions based on immersion in a transparent dopant gas followed by irradiation with a pulsed laser is presented. An alexandrite laser was used, operating at 0.73 μm where photolysis of the dopant gas PH3 does not occur. Multiple pulses of 2.2–2.7 J/cm2 were used to make Si solar cells with total area efficiencies up to 8.6% without benefit of antireflection coatings.
Theory of a modulated barrier photodiode
Authors: Chen C. Y.
Published: February 2003

A theory underlying the operation of a recently reported modulated barrier photodiode has been developed. Energy barrier lowering is shown to be the mechanism responsible for the gain. By balancing the minority-carrier flux in the steady state, the barrier lowering for a given illumination condition can be obtained. The theory agrees very well both qualitatively and quantatively with the experimental results.
Evaluation of secondary ion mass spectrometry profile distortions using Rutherford backscattering
Authors: Clegg J. B. , O’Connor D. J.
Published: February 2003

Distortions which occur in secondary ion mass spectrometry (SIMS) concentration profiles have been studied with samples of Si(Bi) calibrated by Rutherford Backscattering. It is shown that with normal incidence oxygen ion bombardment over the energy range 1–6 keV per atom, the SIMS profile is broadened due to ion beam matrix effects. The true profile shape can be extracted from the energy dependence of the profile width. Profile broadening has also been observed with Si(In) and Si(Sb) but not with Si(B). The observed broadening cannot be explained simply by collisional mixing of the target atoms.
Plasma temperature measurements from highly ionized titanium imploding wire plasmas
Authors: Gersten M. , Rauch J. E. , Clark W. , Richardson R. D. , Wilkinson G. M
Published: February 2003

Electron temperature measurements in highly ionized titanium plasmas are reported. The plasmas were created by imploding cylindrical arrays of fine wires with the Blackjack 5 pulse generator (Peak diode voltage≊3.0 MV, peak current≊4.6 MA, peak power ≊10 TW at full operating level). Temperatures between 0.7 and 2.3 keV were obtained from the slope of the free-bound continuum. The results of these measurements are compared to temperature measurements obtained from the intensity ratio for the H-like (1s–2p)/He-like (1s2–1s3p1P) transitions. The line ratio method gave temperatures which ranged between 1.55 and 2.15 keV. Data are presented from eleven implosions at generator power levels between 5.2 and 7.5 TW.
Volume expansion of ion-implanted diamond
Authors: Maby E. W. , Magee C. W. , Morewood J. H.
Published: February 2003

Boron implantation into diamond at room temperature leads to significant irreversible volume expansion when the boron dose exceeds 5×1015 cm−2. This observation is presumed to reflect an upper limit in the extent to which diamond can be effectively doped with boron by ion implantation. Similar limitations associated with other implant species are anticipated.
Characteristics of an avalanche phototransistor fabricated on a Si surface
Authors: Chen C. W. , Gustafson T. K.
Published: February 2003

A laser-activated avalanche transistor compatible with planar processing has been devised. The I-V characteristics display current-controlled negative differential resistance similar to a bidirectional triggering diode. Capability as an edge detector or as a comb generator was demonstrated. An avalanche current gain of 24 carriers/photon with a 20-V bias was observed when the transistor was used as an optical pulse detector.
Electromigration in aluminum conductors which are chains of single crystals
Authors: Pierce J. M. , Thomas M. E.
Published: February 2003

Electromigration was investigated in 1×4×250 μm aluminum conductors which were recrystallized to produce chains of single-crystal grains, ’’bamboo’’ structures. Median lifetimes were substantially longer than are found in normal polycrystalline Al, reflecting the lack of grain boundary diffusion paths. However, mass fluxes estimated from damage features were larger and more variable than is consistent with a normal lattice diffusion mechanism. An enhanced lattice diffusion mechanism is proposed to account for these observations.
Active mode locking of a XeCl laser
Authors: Reksten Grace , Varghese Thomas , Margulis Walter
Published: February 2003

Active mode locking of a UV preionized transverse discharge XeCl laser has been achieved by modulating the gain using an intracavity Pockel’s cell. The output was 100% modulated, and pulses as short as ∼310 ps were measured. Generation of shorter pulses by the same method is discussed briefly.
A graded-index waveguide separate-confinement laser with very low threshold and a narrow Gaussian beam
Authors: Tsang W. T.
Published: February 2003

A heterostructure semiconductor laser with graded-index waveguide and separate carrier and optical confinements prepared by molecular beam epitaxy is discussed. These lasers have very low broad-area threshold current densities Jth 500 A/cm2 and support narrow beams of Gaussian distribution with far-field half-power full-width in the direction perpendicular to the junction plane ϑ⊥ ∼20°–30°. It is also shown that only when the active layer thickness is ≲700 Å a significantly lower Jth is obtained by employing the symmetric laser structure instead of the regular double heterostructure.