bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystallographic orientation of laser-recrystallized Ge films on fused quartz
Authors: Nishioka Takashi , Shinoda Yukinobu , Ohmachi Yoshiro
Published: February 2003

Crystallographic orientation of laser-recrystallized Ge films on fused quartz has been investigated using a microprobe x-ray diffractometer (μXD) that has a collimated x-ray beam of 30 μm in diameter and a position-sensitive proportional counter. It has been found that the crystallographic orientations normal to the substrate surface were near 〈110〉 or 〈111〉. Tilt angle of the grain from 〈110〉 or 〈111〉 was ≲10°. Orientation distribution was represented by means of a stereographic projection.
Influence of scan speed on deep level defects in cw laser annealed silicon
Authors: Chantre A. , Kechouane M. , Auvert G. , Bois D.
Published: February 2003

Deep level transient spectroscopy has been used to study the influence of the beam scan speed on quenched-in defects in cw laser processed virgin silicon. It is shown that the averaged defect concentration decreases by almost two orders of magnitude as the scan speed is increased from 1 to 100 cm/s for a fixed temperature distribution in the material. Implications regarding technological applications of cw laser processing are briefly discussed.
High coupling and high velocity surface acoustic waves using a c-axis oriented ZnO film on translucent Al2O3 ceramics
Authors: Takeda Fumio , Shiosaki Tadashi , Kawabata Akira
Published: February 2003

The layered structure comprising a c-axis normally oriented ZnO piezoelectric film and a translucent Al2O3 ceramic substrate which has a high surface-acoustic-wave velocity and a small surface roughness has given both a high phase velocity Vp and a high coupling k2 for the 0th (Rayleigh) mode, 1st (Sezawa) mode, and leaky mode surface acoustic waves. The measured maximum values of k2 are 3.6% for the 0th mode at h/λ=0.45 where Vp is 3.2 km/s, 5.7% for the 1st mode at h/λ=0.21 where Vp is 5.6 km/s, and 6.7% for the leaky mode at h/λ=0.16 where Vp is 6.2 km/s, where the interdigital transducers are located at the interface in measuring the above values, and also electrically floating plane metals are on top of the ZnO film for the last two values.
Chaos in rf SQUID’s
Authors: Fesser K. , Bishop A. R. , Kumar P.
Published: February 2003

The response of a superconducting quantum interference device (SQUID) to an oscillating external flux is studied numerically. Parameter ranges for the appearance of complicated periodic and chaotic behavior are given. It is shown that the strange attractor characterizing the chaotic regimes can be described by a one-dimensional return map.
Effect of V/III variation on the optical properties of GaAs and AlxGa1−xAs grown by metalorganic chemical vapor deposition
Authors: Mohammed Khalid , Merz James L. , Kasemset Dumrong
Published: February 2003

A detailed investigation of the effect of the V/III ratio during growth on the optical properties of GaAs and AlGaAs grown by metalorganic chemical vapor deposition is reported, using the low-temperature photoluminescence technique. In the case of GaAs, it was found that the dominant acceptor is carbon and that its concentration decreases monotonically as the As/Ga ratio is increased. For the AlGaAs case, it was found that the concentration of deep impurities increases with decreasing Ga and Al content, but the amount of carbon remains fairly constant.
Periodic window, period doubling, and chaos in a liquid crystal bistable optical device
Authors: Song Jae-Won , Lee Hai-Young , Shin Sang-Yung , Kwon Young-Se
Published: February 2003

A number of periodic windows, i.e., 3, 4, 5, and 7T (T means a period), as well as period doublings up to 4T and chaos, have been observed in a twisted nematic liquid crystal bistable optical device with a delayed feedback. Universal-sequence patterns were confirmed in the observed waveforms. A computer simulation based upon a simple broken-linear modeling of the modulator transmission characteristics shows period doublings, periodic windows, and period mergings. It also exhibits reasonable agreement with the experiment.
Direct amplitude modulation of short-cavity GaAs lasers up to X-band frequencies
Authors: Lau K. Y. , Bar-Chaim N. , Ury I. , Harder Ch. , Yariv A.
Published: February 2003

Experimental and theoretical studies indicate that a high-frequency laser with bandwidths up to X-band frequencies (≳10 GHz) should be one having a short cavity with a window structure, and preferably operating at low temperatures. These designs would accomplish the task of shortening the photon lifetime, increasing the intrinsic optical gain, and increasing the internal photon density without inflicting mirror damage. A modulation bandwidth of >8 GHz has been achieved using a 120-μm laser without any special window structure at room temperature.
Laser writing of discontinuous metal films
Authors: Jipson V. B. , Lynt H. N. , Graczyk J. F.
Published: February 2003

Discontinuous films of noble metals formed by thin-film nucleation demonstrate attractive properties for optical storage applications. Writing energies lower than those for more conventional tellurium based systems have been achieved using 2.0–3.0-nm gold layers in a trilayer configuration. The discontinuous nature of the film is shown to greatly influence the writing characteristics of these films. This is due to the fact that written spots are now formed through laser induced sintering of the small metallic islands, rather than by film ablation that occurs for continuous films.
Vacuum ultraviolet fluorescence of helium in bubbles in aluminum and tin
Authors: Donnelly S. E. , Lucas A. A. , Rife J. C.
Published: February 2003

Vacuum ultraviolet fluorescence is observed from high density helium (up to three times liquid density) in microbubbles in implanted aluminum and tin. The fluorescence is excited by bombardment with low-energy electrons (<5 keV). The resulting spectra are attributed to a combination of excimer (higher wavelength) and atomic (lower wavelength) fluorescences. The efficiency of the process is such that it has recently been proposed for the construction of a new solid state vacuum ultraviolet photon source.
1-W cw Zn ion laser
Authors: Rocca J. J. , Meyer J. D. , Collins G. J.
Published: February 2003

We have obtained 1.2 W of cw laser power on the 4911.6- and 4924.0-Å transitions of Zn II by exciting a He-Zn gas mixture with a dc glow discharge electron beam. In addition, 0.25-W output power has been obtained on the 6149.9-Å line of Hg+ using the same excitation scheme. The combination of electron beam ionization of rare gas atoms and subsequent charge transfer excitation to metal ion levels is shown to have the potential of significantly increasing the efficiency of ion lasers. cw multiwatt visible and ultraviolet ion lasers operating at efficiencies >10−3 appear feasible using this excitation scheme.
Optical gain in GaAs doping superlattices
Authors: Jung H. , Döhler G. H. , Göbel E. O. , Ploog K.
Published: February 2003

The first optical gain measurements have been performed on GaAs doping superlattices grown by molecular beam epitaxy. A maximum gain of 300 cm−1 is obtained in the layered material at a photon energy of 1.35 eV using an excitation density of only 20 W cm−2. Due to the unique tunable energy gap of doping superlattices, the stimulated emission occurs at photon energies far below the gap of bulk GaAs and can be shifted by appropriate choice of the excitation density. Thus, a strong shift of the energetic position of the gain spectra to 1.40 eV with an increased gain of 400 cm−1 is observed when the excitation density is increased to 500 W cm−2.
Experimental estimation of an optical disk system with V-shaped grooves
Authors: Nagashima M. , Takenaga M. , Yamashita T. , Yoshikane T. , Kagata S. , Okino Y. , Kamio K.
Published: February 2003

A new high-density optical disk system has been investigated experimentally. In this system, the optical disk has grooves with a V-shaped cross-sectional configuration. The V-shaped grooves are spaced bottom to bottom by the presently used track pitch, and all walls of the grooves are capable of storing information. The cross talk from information on an adjacent wall has been determined to be almost equal to that of the presently used optical disk, and the new system is verified to double the information density of the optical disk.
Deactivation of group III acceptors in silicon during keV electron irradiation
Authors: Sah Chih-Tang , Sun Jack Yuan-Chen , Tzou Joseph Jengtao , Pan Sam Cheng-Sheng
Published: February 2003

Experimental results on p-Si metal-oxide-semiconductor capacitors (MOSC’s) are presented which demonstrate the electrical deactivation of the acceptor dopant impurity during 8-keV electron irradiation not only in boron but also aluminum and indium-doped silicon. The deactivation rates of the acceptors during the 8-keV electron irradiation are nearly independent of the acceptor impurity type. The final density of the remaining active acceptor approaches nonzero values N∞, with N∞(B)<N∞(Al)Al–H>In-H. These deactivation results are consistent with our hydrogen bond model. The thermal annealing or regeneration rate of the deactivated acceptors in the MOSC’s irradiated by 8-keV electron is much smaller than that in the MOSC’s that have undergone avalanche electron injection, indicating that the keV electron irradiation gives rise to stronger hydrogen-acceptor bond.
Doping considerations for heterojunctions
Authors: Stern Frank
Published: February 2003

The low-temperature mobility in a two-dimensional electron gas with specified electron density Ns in a single, ungated GaAs-Ga1−xAlxAs heterojunction is calculated using several simplifying approximations. The highest mobility for given Ns is attained by using the highest practical donor doping level in the Ga1−xAlxAs and the corresponding undoped spacer layer thickness for charge neutrality. The calculated mobility for given Ns is insensitive to this doping level if values near or above 1018 cm−3 are used, but is sensitive to the doping level in the GaAs and to the difference between the barrier height Vb and the donor binding energy EDb in the Ga1−xAlxAs . For Vb−EDb=0.2 eV, peak mobilities near 2×106 cm2/Vs are reached, at electron densities near 1.3×1011 cm−2, if background doping levels can be held to 1014 cm−3.
Some effects of a longitudinal electric field on the photoluminescence of p-doped GaAs-AlxGa1−xAs quantum well heterostructures
Authors: Miller Robert C. , Gossard Arthur C.
Published: February 2003

Some effects of a longitudinal electric field on the intrinsic and extrinsic photoluminescence of Be-doped GaAs-AlxGa1−xAs multiquantum well samples grown by molecular beam epitaxy have been investigated. The principal sample exhibits four photoluminescence peaks whose relative intensities are observed to change in a very nonuniform manner with forward bias. As the forward bias is reduced (i.e., electric field increased) luminescence is shifted progressively from the free n=1 heavy hole exciton peak to the n=1 heavy hole exciton bound to Be0 peak to an n=1 confined electron-Be0 peak. Changes in the integrated photoluminescence by more than two orders of magnitude are observed over the bias region studied. Shifts in the energy positions of the various peaks with bias are at most of the order of 1 meV.
Quantum well structures of In0.53Ga0.47As/InP grown by hydride vapor phase epitaxy in a multiple chamber reactor
Authors: DiGiuseppe M. A. , Temkin H. , Peticolas L. , Bonner W. A.
Published: February 2003

A computer controlled multiple chamber chemical vapor deposition reactor, designed for the growth of InP based alloys, has been constructed. In this system, specular epitaxial layers of InP and In0.53Ga0.47As are grown in separate chambers. This allows for the uninterrupted growth of In0.53Ga0.47As/InP quantum well structures with layer thicknesses of approximately 150 Å. The photoluminescence spectra of these structures exhibit upward energy shifts as large as 71 meV from the band-gap energy of In0.53Ga0.47As. Laser action at 1.5–1.6-μm wavelengths has been obtained at temperatures up to 100 °C by optical pumping with a Q-switched neodymium:yttrium aluminum garnet laser.
Low reflectivity surface acoustic wave transducers on GaAs
Authors: Grudkowski T. W. , Montress G. K.
Published: February 2003

Experimental results are presented for fabrication and metallization techniques which achieve low reflectivity surface acoustic wave (SAW) interdigital transducer operation on GaAs. The transducer structures considered are single finger pair, quarter wavelength designs with chrome/aluminum/chrome (surface), aluminum (recessed) or gold-germanium/nickel/gold (surface) metallized electrodes which were fabricated directly onto a semi-insulating GaAs substrate. Triple transit signal suppression greater than 53 dB for the recessed aluminum metallization and greater than 62 dB for the Au-Ge/Ni/Au metallization has been achieved for test transducers operating at 159 MHz, compared to typically 30–35 dB for Cr/Al/Cr metallizations. These low reflectivity transducers provide the means for reducing spurious signal responses within monolithic programmable GaAs signal processors and for achieving higher Q performance of SAW resonator filters fabricated on GaAs substrates.
Effects of implantation energy and carbon concentration on the friction and wear of titanium-implanted steel
Authors: Singer I. L. , Jeffries R. A.
Published: February 2003

Dry sliding friction and wear measurements were used to evaluate two implantation processes which increase the C concentration in Ti-implanted steels. In the first process, Ti ions were implanted at a low energy (50 keV) in order to enhance the efficiency of vacuum carburization over what is achievable at higher energies (e.g., 190 keV). In the second, a dual implantation process, C ions were implanted into steels already implanted with Ti ions at high energy (190 keV). The first process produced a low friction (μ=0.3), scuff resistant surface at a fluence of 2×1017/cm2, 40% lower than the fluence required for similar behavior by 190-keV implants. At fluences of 2×1017/cm2 each, the dual implantation produced a modest decrease in friction (μ=0.5), accompanied by stick slip, and some wear resistance compared to nonimplanted steel (μ=0.6). Auger spectroscopy and energy-dispersive x-ray analysis were used to analyze the surface composition produced by the two processes at fluences of 2×1017/cm2. The dual implanted surface had more Ti, more C, and a greater C/Ti ratio than the low-energy implanted surface. The latter, however, had more C derived from vacuum carburization than the dual implanted surface. Both processes resulted in identical surface C concentrations. We concluded, therefore, that the improved tribological surface of Ti-implanted steel results from vacuum carburization and not just the presence of excess C.
Synthesis of novel inorganic films by ion beam irradiation of polymer films
Authors: Venkatesan T. , Wolf T. , Allara D. , Wilkens B. J. , Taylor G. N.
Published: February 2003

We propose a novel technique to convert polymer films into useful inorganic films by ion beam irradiation. Along the track of an ion the polymer is dissociated into smaller fragments. Volatile fragments diffuse through the film and escape. Any element which is not removed in the form of volatile species is subsequently enriched with respect to the other elements. We demonstrate this effect in a polymer poly(dimethylsilylene-co-methylphenylsilylene), which initially has a C:Si ratio of 4.5:1. Upon irradiation with 2-MeV Ar+ ions at a dose of 1015 ions/cm2 the C:Si ratio changes to 3.4:1 as verified by Rutherford backscattering spectrometry. We believe that the effect of the ion beam irradiation is to produce more Si–C bonds at the expense of the C–H and Si–Si bonds, with ≲10% of the original hydrogen being present in the film at high doses. The IR spectra of the film as a function of the irradiation dose show a progressive loss of fine molecular features with significant increase of the refractive index. The IR spectrum at the high doses appears to be due to a mixture of various Si and C bonds. However, the irradiated films are very hard and scratch resistant (knoop value ≳1300), suggesting an increase in the number of silicon carbide bonds.
Silicon self-interstitial supersaturation during phosphorus diffusion
Authors: Harris R. M. , Antoniadis D. A.
Published: February 2003

The effect of phosphorus introduction and diffusion on the diffusivities of boron, arsenic, and antimony in silicon was studied using arsenic and antimony buried layers in a boron-doped silicon substrate. It was found that the diffusivity of boron and arsenic was enhanced, while that of antimony was retarded directly under the silicon surface exposed to phosphorus. Since antimony diffuses primarily via a vacancy mechanism while the other two elements via a combination of vacancy and interstitialcy mechanisms, these results suggest that phosphorus predeposition enhances the silicon self-interstitial concentration and reduces the concentration of vacancies.
Hg vacancy related lifetime in Hg0.68Cd0.32Te by optical modulation spectroscopy
Authors: Polla D. L. , Aggarwal R. L. , Nelson D. A. , Shanley J. F. , Reine M. B.
Published: February 2003

The lifetime of excess photogenerated carriers has been measured as a function of temperature and carrier concentration in p-type Hg0.68Cd0.32Te by contactless optical modulation spectroscopy. An excess carrier lifetime related to impurity substitution on ionized Hg sites is suggested as the dominant Shockley–Read recombination mechanism observed in this material.
Infrared rapid annealing of Zn-implanted GaAs
Authors: Suzuki T. , Sakurai H. , Arai M.
Published: February 2003

Infrared rapid annealing was used to activate Zn which had been heavily implanted into GaAs substrate at a variety of annealing temperatures, temperature hold times, and heating rates. With no capping insulator and no As vapor pressure, an activation efficiency over 90% was obtained by annealing at 800 °C with zero hold time. It was found that prolonging the temperature hold time and slowing down the heating rate reduced the activation efficiency. In-depth profiles of holes and atomic Zn in the annealed samples were analyzed by differential Hall measurement and secondary ion mass spectroscopy, respectively. Both profiles have double peaks, implying depletion of Zn atoms around Rp. Measurement of backscattering yield revealed that crystallographic recovery of implantation-induced damage is more rapid at higher heating rate.
Stable longitudinal mode operation in a multiple twisted double-heterostructure laser
Authors: Sugino Takashi , Wang Shyh
Published: February 2003

A multiple twisted double-heterostructure laser is fabricated by connecting a terraced substrate laser and a channeled substrate laser alternately. In addition to a stable tranverse-mode oscillation due to the built-in refractive index variation, a stable longitudinal-mode oscillation is achieved by interferometric effects which are caused by internal reflection at twisted parts of the composite cavity where transition in the laser structure occurs. The laser with two twisted regions shows a threshold current of 92 mA, and wavelength locking over a temperature range of more than 25 °C within which the wavelength changes at a rate of 0.6 Å/ °C.
Intensity-dependent index of refraction in multilayers of polydiacetylene
Authors: Carter G. M. , Chen Y. J. , Tripathy S. K.
Published: February 2003

We have grown multilayer samples of a polydiacetylene upon a metallized grating forming a planar waveguide structure. By measuring the change with optical intensity in the coupling angle between an input laser beam and a planar waveguide mode in the structure we estimate the intensity-dependent index of refraction, n2≂10−6 (MW/cm2)−1 (λ>7500 Å), for the polydiacetylene. Also, a large resonant enhancement of the optical nonlinearity was observed.
Low loss waveguides grown on GaAs using localized vapor phase epitaxy
Authors: Erman M. , Vodjdani N. , Theeten J. B. , Cabanié J. P.
Published: February 2003

New type of optical waveguides grown on GaAs by localized epitaxy using vapor phase epitaxy is presented. The guides are grown through a strip opened in a dielectric film and have a triangular cross section. The loss measurements have been performed on waveguides of lengths varying from 1 to 10 mm. Losses as low as 1.5 dB have been found. An original light coupling technique into the guide—through the substrate—has been used. Because of an improved optical confinement due to the structure of the guides and because of their low losses, these waveguides have numerous potential advantages and applications in integrated optics.
Influence of Cu as an impurity in Al/Ti and Al/W thin-film reactions
Authors: Krafcsik I. , Gyulai J. , Palmström C. J. , Mayer J. W.
Published: February 2003

Thin-film reactions of Al/Ti and Al/W with 3 at. % Cu in Al were investigated by glancing-angle x-ray diffraction and Rutherford backscattering for vacuum annealing in the temperature range 300–500 °C. In the Al/Ti system, the intermetallic phase Al3Ti grows as (time)1/2. The presence of Cu in Al retards the growth rate by an order of magnitude at 400 °C and increases the activation energy from 1.8±0.1 to 2.4±0.1 eV. In the Al/W system, the presence of Cu retards the penetration of W into Al.
Photo-oxidation of silicon monoxide to silicon dioxide with pulsed far-ultraviolet (193 nm) laser radiation
Authors: Blum S. E. , Brown K. H. , Srinivasan R.
Published: February 2003

Silicon monoxide films (1000–5000 Å thick) are converted to silicon dioxide when irradiated in air with pulses (∼15 n half-width) of 193-nm radiation (40–110 mJ/cm2) from an excimer laser. The quantum efficiency of the process has a minimum value of 0.014.
Anion inclusions in III-V semiconductors
Authors: Gant H. , Koenders L. , Bartels F. , Mönch W.
Published: February 2003

On all surfaces cleaved from InP, GaP, GaAs, and GaSb a local excess of anion atoms was detected as bright spots in the image of the electron current absorbed by the samples and identified by using a scanning Auger electron spectrometer exhibiting a spatial resolution of 20 μm. Arsenic zones were detected on horizontal Bridgman- as well as liquid encapsulation Czochralski grown GaAs indicating their existence to be independent of the crystal growth technique. The densities of anion zones varied between 10 and 500 per square centimeter on a cleave-to-cleave basis. Their diameters typically measured approximately 50 μm. The investigations indicate that the anion zones originate from inclusions in the bulk becoming exposed by cleavage.
Effective medium analysis of TeOx optical storage layers
Authors: Seki H.
Published: February 2003

The optical properties of Te suboxide type optical memory disk media have been analyzed in terms of the Maxwell Garnett theory of particulate composites. Using the optical indices reported in the literature for amorphous and polycrystalline Te the essential features of the reflectivity spectrum of an optical disc consisting of tellurium suboxide have been simulated. This result supports the interpretation that these suboxide films have extremely fine granular structures. This composite structure has been speculated to be an important factor which enables some of this type of storage medium to repeat numerous amorphous-crystalline transition cycles.
Electron kinetics of silane discharges
Authors: Garscadden A. , Duke G. L. , Bailey W. F.
Published: February 2003

A numerical solution of the Boltzmann transport equation for electrons has been used to calculate the electron energy distribution function in silane for a range of applied steady-state fields. This enables the evaluation of the fractional energy transfer for vibrational excitation and dissociation, the rate coefficients for the different processes and the electron transport properties.
New long wavelength Al0.48In0.52As/Ga0.47In0.53As avalanche photodiode grown by molecular beam epitaxy
Authors: Capasso F. , Alavi K. , Cho A. Y. , Foy P. W. , Bethea C. G.
Published: February 2003

We report the first Al0.48In0.52As/Ga0.47In0.53As long wavelength avalanche photodiode. The device, grown by molecular beam epitaxy, has high responsivities over a wide spectral range (0.85–1.7 μm). Avalanche gains of ≂27 at relatively low operating voltages (≲30 V) are observed. The band edge discontinuities of this heterojunction make these devices potentially faster than similar abrupt structures of InP/Ga0.47In0.53As. Fast response with a full width at half-maximum of ≂250 ps and no tails are observed.
Evidence for a dense electron-hole plasma close to the melting phase transition in silicon
Authors: Fauchet P. M. , Siegman A. E.
Published: February 2003

We have studied both theoretically and experimentally the dynamics of laser-induced electron-hole plasmas created at the surface of silicon using the strong synergy observed during simultaneous illumination by two picosecond pulses of different wavelengths. In a range of intensities up to those capable of producing a phase transition, we find good agreement between the results of our experiments and the predictions of a conventional model for pulsed laser heating.
Substrate temperature dependence of microcrystallinity in plasma-deposited, boron-doped hydrogenated silicon alloys
Authors: Rajeswaran G. , Kampas F. J. , Vanier P. E. , Sabatini R. L. , Tafto J.
Published: February 2003

The glow-discharge decomposition of silane diluted in hydrogen using diborane as a dopant results in the deposition of p-type microcrystalline silicon films at relatively low temperatures. The conductivity of these films is critically dependent on the substrate temperature when the ratio of silane flow rate to total gas flow rate is 1%. Electron micrographs show that highly conducting films contain numerous clusters of 2.5-nm crystallites that are embedded in an amorphous medium.
Structure of thermally induced microdefects in Czochralski silicon after high-temperature annealing
Authors: Ponce F. A. , Yamashita T. , Hahn S.
Published: February 2003

The microstructure of Czochralski silicon annealed at high temperatures has been investigated using high resolution transmission electron microscopy. After prolonged heat treatments at temperatures close to 1200 °C, two types of microdefects are observed: (a) small polyhedral oxide precipitates, with typical diameters of about 15 nm and facets along crystalline planes of the silicon matrix, and (b) planar faults along {111} planes which have been directly identified as extrinsic stacking faults bounded by Frank-type dislocations.
As4/Ga flux ratio dependence on Si incorporation in molecular beam epitaxial GaAs
Authors: Akimoto K. , Dohsen M. , Arai M. , Watanabe N.
Published: February 2003

The effect of the As4/Ga flux ratio R on Si incorporation into GaAs grown by molecular beam epitaxy has been investigated by studying the electrical characteristics and the secondary ion mass spectroscopy. It was found that the Si sticking coefficient depend on R, and the incorporation mechanism was expected to be different in the region between 0.7<R<8 and 8<R<40. A model to explain observed results is proposed.
Hole burning spectroscopy of R′ aggregate color centers in polycrystalline LiF thin films using a GaAlAs diode laser
Authors: Ortiz Carmen , Afonso Carmen N. , Pokrowsky Peter , Bjorklund Gary C.
Published: February 2003

The first spectroscopic measurements of R′ aggregate color centers contained in polycrystalline LiF hosts are reported. The inhomogeneous and homogeneous widths of the 830-nm zero phonon line are measured by conventional grating spectroscopy and by photochemical hole burning spectroscopy using a current tuned GaAlAs diode laser with 3-mW output power. An extensive photochemical hole burning comparison between single and polycrystalline samples is presented.
Metalorganic chemical vapor deposition of oriented ZnO films over large areas
Authors: Smith Frank T. J.
Published: February 2003

A metalorganic chemical vapor deposition process for preparing c-axis-oriented ZnO films in a simple system of the type commercially available for SiO2 deposition is described. The resulting layers are highly uniform in thickness and adhere to a variety of substrates. Film properties and structure are described briefly.
Gigahertz bit rate analog to digital conversion with optical outputs using cleaved-coupled-cavity semiconductor lasers
Authors: Olsson N. A. , Tsang W. T. , Logan R. A. , Patel C. K. N.
Published: February 2003

A combined high-speed analog to digital converter, and optical transmitter, based on the frequency tuning capability of cleaved-coupled-cavity semiconductor lasers is proposed and demonstrated. The device, which acts as a level discriminator with optical outputs can either continuously sample the analog input or be strobed at rates up to ∼ 1 Gsamples/s. A four-level conversion of a 100-MHz sinusoidal input is shown.
Tunable narrow-linewidth oscillations and current-voltage characteristics of a resistive dc SQUID
Authors: Verschueren J. M. V. , Uiterwaal A. A. , van der Heijden R. W. , Wyder P.
Published: February 2003

The output voltage of a dc superconducting quantum interference device (SQUID) containing a resistive section Rs oscillates at a frequency νq =Vs/ φ0 (φ0=flux quantum) when a current controlled voltage Vs is maintained across Rs. These oscillations have been observed from ∼10−1 to 1011 Hz, using Rs values ranging from ∼10−10 to ∼10−3 Ω in low inductance (∼10−10 H) point contact SQUID loops. At high frequencies, they manifest themselves in the dc current-voltage characteristics by inducing extra current steps.
Simultaneous ultraviolet laser triggering of two multimegavolt gas switches
Authors: Adams R. G. , Smith D. L. , Woodworth J. R.
Published: February 2003

The output from a low-beam-divergence KrF ultraviolet laser has been used to simultaneously trigger two multimegavolt gas-filled switches emersed in a water dielectric. Focusing 55 mJ of laser energy into the interelectrode gap of each switch has produced simultaneity jitter of ≤1.7 ns for closure of both 2.40-MV self-breakdown voltage (SBV) switches. Both switches have displayed essentially identical switching behavior, with individual switch jitter ≲2.3 ns. The triggering delay to switch closure after laser irradiation of the switch has exhibited linear dependence upon switch voltage in the 60%–90% SBV region.
Time-resolved temperature measurement of picosecond laser irradiated silicon
Authors: Lompré L. A. , Liu J. M. , Kurz H. , Bloembergen N.
Published: February 2003

Time-resolved reflectivity and transmission measurements of crystalline silicon films reveal lattice heating through the temperature dependence of the complex index of refraction. The temperature rise, which is much higher than derived by others from Raman scattering experiments, occurs in a surface layer of 100-nm thickness.
Profile control by chemically assisted ion-beam and reactive ion beam etching
Authors: Chinn J. D. , Adesida I. , Wolf E. D.
Published: February 2003

Investigations with broad-beam argon and reactive fluorinated ion beams have shown that the etched wall profiles of silicon at submicrometer linewidths can be controlled by varying the ion energy, current, and partial pressure of XeF2. Inert argon and reactive ion beams generated from xenon difluoride produced overcut profiles resulting from predominantly physical etching mechanisms. With very low partial pressures of XeF2 in the background ambient, purely chemical etching of silicon is low while enhanced line-on-sight ion-assisted etching can be used to produce vertical profiles. By increasing the background partial pressure of XeF2, undercut profiles were produced by purely chemical and chemically assisted ion beam mechanisms. Thus, various wall profiles were produced in silicon within the same broad-beam ion etching equipment using the same two-component gas system of Ar and XeF2.
Surface ripples in laser-photochemical wet etching of gallium arsenide
Authors: Tsukada Noriaki , Sugata Sumio , Saitoh Hiroshi , Mita Yoh
Published: February 2003

Surface ripples of submicrometer spatial period are observed in laser enhanced etching with liquid etchants. The surface ripple formation in the laser-photochemical wet etching is not explained by the surface polariton model which needs melting of the semiconductor surface. To explain this ripple formation, we have to consider other mechanisms for ripple formation which does not need melting of the semiconductor surface, such as Raman excitation of surface polariton, polarization charge model, and bulk-selvedge coupling model. We suggest that this low power and high speed laser-photochemical etching provides a valuable one-step process for producing the fine diffraction gratings required by integrated optics.
Measurement of carrier and lattice heating in 1.3-μm InGaAsP light-emitting diodes
Authors: Manning J. , Olshansky R. , Su C. B. , Powazinik W.
Published: February 2003

The hot-carrier effects reported for InGaAsP light-emitting diodes are shown to result primarily from lattice heating. The small amount of heating observed at currents corresponding to typical threshold current density has negligible effect on the characteristic temperature T0 measured for InGaAsP lasers under pulsed conditions.
Phase-locked InGaAsP laser array with diffraction coupling
Authors: Chen T. R. , Yu K. L. , Chang B. , Hasson A. , Margalit S. , Yariv A.
Published: February 2003

A phase-locked array of InGaAsP lasers has been fabricated for the first time. This 50-μm-wide array utilized diffraction coupling between adjacent lasers to achieve phase locking. Threshold current as low as 200 mA is obtained for arrays with 250-μm cavity length. Smooth single-lobe far-field patterns with beam divergence as narrow as 3° have been achieved.
Reliability of constricted double-heterojunction AlGaAs diode lasers
Authors: Botez D. , Connolly J. C. , Ettenberg M. , Gilbert D. B. , Hughes J. J.
Published: February 2003

Constricted double-heterojunction diode lasers have been life tested at 70 °C heatsink temperature and 3–4 mW/facet in cw operation. A median life of 7800 h is obtained at 70 °C, which extrapolates to 4×105 h median life at room temperature. The extrapolated mean time to failure at room temperature is in excess of 106 h. Single-longitudinal-mode cw operation is maintained after 10 000 h of accelerated aging at 70 °C.
Selective electrochemical etching of p-CdTe (for photovoltaic cells)
Authors: Tenne R.
Published: February 2003

The electrochemical etching of p-CdTe is investigated. This etching is based on a method used previously for the selective etching of n-type Cd-chalcogenide semiconductors. We show that the electrochemical etching creates a dense pattern of submicron pits, and increases the reverse bias photocurrent of a Schottky barrier device, made up of single crystal p-CdTe and a polysulfide electrolyte typically by 20%. Evidence for the selective removal of surface defects is brought up and the conditions for selective etching are discussed in brief.
Deactivation of the boron acceptor in silicon by hydrogen
Authors: Sah Chih-Tang , Sun Jack Yuan-Chen , Tzou Joseph Jeng-Tao
Published: February 2003

Two new experiments are presented which suggest that the ‘‘bulk-compensating donor’’ phenomenon observed in p-Si is probably a deactivation process of the boron acceptor by hydrogen with the formation of a B−H+ pair. The two experiments are (i) avalanche hole injection in Al-gate metal-oxide-silicon capacitor from boron-diffused n-Si substrate and (ii) 5-keV electron irradiation of Al/p-Si Schottky diodes. Atomic hydrogen may be released by the avalanche injected energetic electrons or holes or keV electrons from the Al–H, AlO–H, Si–H, and SiO–H sites in the Al gate and the SiO2 film as well as at the Al/SiO2 and SiO2/Si interfaces, which may then migrate to the boron acceptor sites to form the B−H+ pair. Observed hydrogen bond breaking rate by holes is as much as two orders of magnitude larger than by electrons, which is consistent with the thermal hole capture and energetic electron impact bond-breaking models.
Large area electron beam annealing
Authors: Moore Cameron A. , Rocca J. J. , Johnson T. , Collins G. J. , Russell P. E.
Published: February 2003

We have achieved wide area (38 cm2) electron beam annealing of ion implanted silicon wafers using a glow discharge electron beam with electron energies between 3 and 7 keV. A continuous beam 7 cm in diameter with a power density up 90 W/cm2 was used to anneal the 7-cm-diam central portion of boron-implanted (30 keV, 5×1015 atoms/cm2) n-type 〈100〉 silicon wafers 10 cm in diameter. Annealing was obtained without redistribution of the original dopant profile using a 15-selectron beam exposure. Due to the high electron beam power density achieved over a large area, one can uniformly anneal an entire wafer in a single exposure without sample or beam scanning.
Anomalous longitudinal mode behavior of a deep Zn-diffused GaAs/GaAlAs laser
Authors: Choi H. K. , Wang Shyh
Published: February 2003

Observation of anomalous longitudinal mode behavior from deep Zn-diffused GaAs/GaAlAs lasers is reported. Single longitudinal mode operation is maintained without any mode hopping over a temperature range of more than 40 °C when the current is fixed. The spectrum, however, is quite sensitive to current changes.
Streak camera study of short pulse generation in an optically pumped GaAs/(GaAl)As laser
Authors: Dawson M. D. , Sibbett W. , Vukusic J. I. , Dawson P. , Duggan G. , Foxon C. T.
Published: February 2003

A synchronously operated picosecond streak camera has been used in a direct time-resolved study of luminescence and laser emission from a GaAs/(GaAl)As double heterostructure laser pumped by <90 ps, 514-nm optical pulses from a mode-locked Ar ion laser. Semiconductor laser pulse widths down to 20 ps were recorded and the dependence of the temporal characteristics of these pulses on average pump power was investigated.
Effect of an active layer thickness on lateral and longitudinal modes of a gain guiding laser with a tapered stripe structure
Authors: Mamine Takayoshi , Kawai Hiroji
Published: February 2003

Effect of an active layer thickness on the lateral and longitudinal modes of the gain guiding laser with a tapered stripe structure has been studied. We observed broadening in the linewidth of each longitudinal mode as well as continuous emission spectra for the tapered stripe lasers with the thicker active layer of more than 0.1 μm. From the measurement of longitudinal as well as lateral modes, it is concluded that hole burning effect is enhanced in the thicker active layer as was pointed out by Copeland. The experimental results observed for the tapered stripe lasers are inherent to gain guiding lasers with a stripe geometry structure.
Epitaxial NiSi2 formation by pulsed laser irradiation of thin Ni layers deposited on Si substrates
Authors: Grimaldi M. G. , Baeri P. , Rimini E. , Celotti G.
Published: February 2003

Pulsed laser irradiation was used to induce silicide formation in Ni thin layer deposited onto Si substrates of 〈100〉 and 〈111〉 orientation, respectively. Suitable energy densities of the 30-ns Nd glass laser pulse produced epitaxial NiSi2 silicide for a 15-nm-thick Ni layer. Irradiation of thicker metal films formed instead several silicides of nonuniform composition.
Temperature-dependent ion mixing and diffusion during sputtering of thin films of CrSi2 on silicon
Authors: Shreter U. , Fernandez R. , Nicolet M-A.
Published: February 2003

Measurements of sputtering yields and composition profiles have been carried out using backscattering spectrometry for samples of CrSi2 on Si irradiated with 200-keV Xe ions. When the CrSi2 layer is thinner than the ion range, the sputtering yield ratio of Si to Cr increases from 3.5 for room-temperature irradiation to 65 at 290 °C. For a thick sample, the corresponding increase is from 2.4 to 4.0. only. These changes are explained in terms of a rise in the Si surface concentration at 290 °C. The driving force for this process seems to be the establishment of stoichiometric CrSi2 compound. Transport of Si to the surface is by ion mixing in the thin sample and thermal diffusion through the thick layer.
Pore size distribution of shaley rock by small angle neutron scattering
Authors: Hall P. L. , Mildner D. F. R. , Borst R. L.
Published: February 2003

Information concerning pore microstructure of shaly rocks is of considerable relevance to petroleum exploration and production. Pore sizes and distributions within shaly samples have been determined by small angle neutron scattering. The data are indicative of a considerable spread of pore dimension, showing inhomogeneities with a range from 20 Å and greater. The cumulative pore volumes are compared with those derived from mercury intrusion porosimetry and nitrogen adsorption and desorption isotherms.
Hall mobility in undoped microcrystalline Si:H,Cl films
Authors: Augelli V. , Murri R. , Ligonzo T.
Published: February 2003

The Hall mobility in undoped microcrystalline Si:H, Cl films has been measured in the temperature range 130<T<300 K. The dependence of μH on the temperature clearly evidences two different transport mechanisms. Above T0≂200 K, the Hall mobility has an activation energy of about 0.3 eV, while below T0 it is practically temperature independent.
Photoluminescence associated with thermally induced microdefects in Czochralski-grown silicon crystals
Authors: Tajima Michio , Gösele U. , Weber J. , Sauer R.
Published: February 2003

Photoluminescence in the photon energy range 0.7–1.2 eV is investigated for commercial Czochralski-grown Si crystals subjected to isothermal annealing at 650 °C for 1–450 h. A strong and sharp line appears at 0.903 eV at certain annealing stages, regardless of the sources and the conductivity type of starting materials. The intensity dependence of the 0.903-eV line on the annealing time coincides with the concentration dependence expected for Si self-interstitials emitted during the oxygen precipitation process. This is experimental evidence that microdefects responsible for this line are correlated with Si self-interstitials.
Hydrogenated amorphous silicon produced by laser induced chemical vapor deposition of silane
Authors: Meunier M. , Gattuso T. R. , Adler D. , Haggerty J. S.
Published: February 2003

The electronic properties of hydrogenated amorphous silicon (a-Si:H) produced by laser-induced chemical vapor deposition of silane are reported. Spin density and both optical gap and hydrogen content increased with decreasing substrate temperature. Electrical conductivities are reported. Film properties are superior to those produced by conventional chemical vapor deposition of silane.
Low compensation vapor phase epitaxial gallium arsenide
Authors: Colter P. C. , Look D. C. , Reynolds D. C.
Published: February 2003

Vapor phase epitaxial gallium arsenide (GaAs) layers, with lower compensation ratios than any reported heretofore, have been reproducibly grown by the Ga/H2/AsCl3 method. One of these samples has been studied extensively by electrical measurements and shows an acceptor concentration of (2.0±0.7)×1013 cm−3, and a compensation rate of NA/ND =0.06±0.02. These numbers are supported by magnetophotothermal spectroscopy and photoluminescence measurements. The preparation involves growth on [211A] substrates, and a pregrowth bakeout of the Ga source, which results in a significantly lower Zn acceptor concentration in the layer. These results have important implications for various compensation mechanisms which have been proposed for GaAs.
XeCl excimer laser excited by longitudinal discharge
Authors: Zhou Zhenzhuo , Zeng Yongjian , Qiu Mingxin
Published: February 2003

XeCl excimer laser excited by longitudinal gas discharge is reported. The main characteristics of the laser output and the laser energy in dependence of the operating parameters were measured. The laser pulse duration was 35 ns and the maximum laser energy 317 μJ with improvement by preionization.
Measurement of compositional inhomogeneity of liquid phase epitaxial InGaPAs
Authors: Brunemeier P. E. , Roth T. J. , Holonyak N. , Stillman G. E.
Published: February 2003

Precision x-ray measurements have been performed on the compositional inhomogeneity that occurs during the initial part of the liquid phase epitaxial (LPE) growth of InGaPAs on InP substrates from step-cooled solutions. Double crystal x-ray diffraction and absorption data are presented on epitaxial layers grown short term (30 ms) and long term (1–2 min). These data are used to determine the difference in alloy composition of the two growth methods. This study indicates that long-term LPE growth of quaternary alloys is inhomogeneous, while short-term growth can be made uniform.
Oxygen vacancies in lithium niobate
Authors: Sweeney K. L. , Halliburton L. E.
Published: February 2003

Optical absorption peaks at 760 and 500 nm in LiNbO3 are assigned to oxygen vacancies containing one and two electrons, respectively. The 500-nm band appears after annealing above approximately 500 °C in a vacuum, i.e., a reducing atmosphere, and continues to grow with increasing anneal temperature. Optical bleaching near 77 K destroys the band at 500 nm and produces both a band at 760 nm and a Nb4+ electron spin resonance spectrum. The spectral dependence of the bleaching light required to convert the 500-nm band to the 760-nm band is determined.
High-resistivity (>105 Ω cm) InP layers by liquid phase epitaxy
Authors: Rezek E. A. , Zinkiewicz L. M. , Law H. D.
Published: February 2003

Experimental conditions suitable for the liquid phase epitaxial growth of InP epilayers with resistivities >105 Ω cm have been investigated. It has been found that the resistivities of Fe-doped InP layers are, in fact, less than the resistivity of an undoped InP control sample. Furthermore, the resistivity decreases monotonically as more Fe dopant is added to the melt. When Co is used as a dopant, the same growth conditions used for the Fe-doped InP produce InP epilayers with ρ>105 Ω cm. High-resistivity InP layers have been reproducibly grown with 1.0 and 0.6 at. % of Co added to the melt. The high-resistivity InP epilayers have been grown at various temperatures between 715 and 630 °C.
Inductive monopole detector employing planar high order superconducting gradiometer coils
Authors: Tesche C. D. , Chi C. C. , Tsuei C. C. , Chaudhari P.
Published: February 2003

The characteristics and performance of a family of high-order planar gradiometer detectors for inductive detection of magnetic monopoles are discussed. Conventional superconducting magnetometers used for monopole detection must be operated in an extremely stable, low field environment. This places a severe restriction on the cross-sectional area of such detectors. However, planar gradiometer detectors permit the use of relatively large area detectors in coincidence without requiring a corresponding increase in the stability of the ambient field.
Degenerate four-wave mixing due to intervalance band transition in p-type mercury cadmium telluride
Authors: Yuen S. Y.
Published: February 2003

Degenerate four-wave mixing in p-type HgCdTe has been observed with CO2 lasers. A room temperature, third order nonlinear susceptibility χ(3) of 8×10−6 esu has been measured. This is the largest χ(3) with picosecond relaxation time reported. The observed nonlinearity is interpreted in terms of the effective mass change induced by the transition from the heavy to light hole band. This process is shown to be stronger than the nonlinearity caused by the saturation of the intervalence band absorption.