bluuebunny/crossref_metadata_2025 huggingface dataset:
Microscopic model for the ablative photodecomposition of polymers by far-ultraviolet radiation (193 nm)
Authors: Garrison Barbara J. , Srinivasan R.
Published: February 2003

Short pulses of far-ultraviolet (193 nm) laser radiation are capable of etching organic polymer films without melting the remaining sample. The mechanism proposed for this ablative photodecomposition attributes ablation to the increase in volume that accompanies the photolysis of the polymer. A model of the microscopic process is presented here. The predictions of the model include ablation without melting, a mean perpendicular ejection velocity of 1300 m/s, and an angular distribution of the ablated material which has a narrow peak normal to the surface.
Ferromagnetic resonance depth profiles of magnetic tapes using frequency-dependent photoacoustic detection
Authors: Netzelmann U. , Pelzl J.
Published: February 2003

Depth profiles of layered ferromagnetic tapes were studied using photoacoustically detected ferromagnetic resonance. The photoacoustic (PA) response was measured as a function of external magnetic field at different modulation frequencies ranging from 35 Hz to 23.5 kHz. The resonance pattern of the ferromagnetic coverlayer could be resolved in the recordings of the PA amplitudes at high frequencies. An estimate of the layer thickness was obtained from the observed PA phase angle shifts.
Computer simulation of planar ion implanted optical waveguides in lithium niobate
Authors: Shail R. , Naden J. M. , Weiss B. L.
Published: February 2003

A new numerical approach is outlined to the problem of calculating the normal modes of electromagnetic wave propagation in a graded-index planar optical waveguide. The method is versatile, directed at the type of refractive-index profile produced by ion implantation, and promises to facilitate the investigation of multiregion problems.
Intense source of monochromatic electrons: Photoemission from GaAs
Authors: Feigerle C. S. , Pierce D. T. , Seiler A. , Celotta R. J.
Published: February 2003

Measurements of intensity and width of the energy distribution for photoemission from negative electron affinity GaAs have been made as a function of surface preparation and temperature. Energy distributions as narrow as 31 meV (full width at half-maximum) have been obtained. The measured currents are compared to those which are currently available by coupling thermionic cathodes with electron monochromators and found to be at least 10 times as intense for distributions of equivalent width.
Mechanism of surface conduction in semi-insulating GaAs
Authors: Chang M. F. , Lee C. P. , Hou L. D. , Vahrenkamp R. P. , Kirkpatrick C. G.
Published: February 2003

The space-charge-limited current leakage in processed semi-insulating GaAs wafer has been found to occur very close to the surface. The depth profile of the EL2 traps has been calculated from the measured trap-fill-limited voltage (Vt) of the leakage current versus etch depth and agrees well with the reported experimental result. A proposed mechanism of surface conduction is presented based on EL2 outdiffusion. The calculated substrate I-V relation agrees quantitatively with the measured results.
Identification of germanium and tin donors in InP
Authors: Skolnick M. S. , Dean P. J. , Taylor L. L. , Anderson D. A. , Najda S. P. , Armistead C. J. , Stradling R. A.
Published: February 2003

Central cell structure due to germanium and tin donors in InP is identified in carefully back-doped vapor phase epitaxial material. Both near band edge photoluminescence and far infrared photoconductivity in high magnetic fields are employed to resolve spectral features arising from different donor species. Relative to the likely effective mass donor binding energy of 5.46 meV, the Ge and Sn chemical shifts are deduced to be 0.30 and 0.21 meV, respectively.
Critical current density of bronze-processed multifilamentary Nb3Sn wires with magnesium addition to the matrix
Authors: Wu I. W. , Dietderich D. R. , Johnson-Walls P. E. , Glazer J. , Holthuis J. T. , Hassenzahl W. V. , Morris J. W.
Published: February 2003

The effects of the addition of magnesium to the bronze of a bronze-processed multifilamentary Nb3Sn conductor were studied. The bronze composition was varied from Cu-6.7 Sn-0.0 Mg to Cu-6.7 Sn-0.62 Mg. The magnesium was found to refine the Nb3Sn grain size and improve the critical current density of the superconductor. The most heavily doped wire had an optimum critical current density three to six times better than the Mg-free control wire at all fields.
Application of spin-coated As2S3 thin films in a high resolution trilayer resist system
Authors: Singh B. , Chern G. C. , Lauks I.
Published: February 2003

We propose a new trilayer resist system (photoresist/As2S3/polymethyl methacrylate) using spin-coated As2S3 (0.20  μm thick) as a barrier layer. As2S3 has shown high etch rate (more than 30 times) in SF6+4% O2 reactive ion etching compared to organic photoresists which allows a precise pattern transfer. The spin coating process of As2S3 is compatible with conventional processing. As2S3 has high absorption coefficient in ultraviolet and deep UV eliminating substrate reflection. Patterns of micron and submicron dimensions were replicated successfully.
Use of high magnetic fields to estimate carrier leakage current in GaInAsP-InP double heterostructure lasers
Authors: Arakawa Yasuhiko , Nishioka Masao , Miura Noboru
Published: February 2003

We demonstrate a novel technique for estimating carrier leakage current in double heterostructure lasers. This utilizes the dependence of the carrier leakage motion on the high magnetic field directions. The carrier leakage current near threshold in GaInAsP-InP lasers is estimated as a function of temperature from −25 to 65 °C. The result indicates that the T0 value is improved from 58 to about 77 °C by suppressing the leakage current.
Electronic effect on crystallization growth velocities produced by charged dangling bonds in a-Si
Authors: Mosley L. E. , Paesler M. A.
Published: February 2003

Ion implantation of electrically active dopants in silicon lowers the activation energy measured in crystallization growth velocity studies. Evidence indicates that this change is due to an electronic effect, arising from the charging of dangling bonds which produces a shift in the Fermi level on both sides of the amorphous-crystalline interface. The difference in the shifts of the Fermi levels in the bulk amorphous and crystalline Si is identified as being equal to the change in activation energy. We find the negatively and positively charged dangling bond states to be separated by approximately 0.35 eV, and roughly centered about midgap.
Electronic state localization in semiconductor superlattices
Authors: Lang Roy , Nishi Kenichi
Published: February 2003

It is shown that in semiconductor superlattices slight fluctuations in the layer thicknesses and alloy compositions are likely to cause strong localization of electronic states. Such localization will hinder miniband formation or band folding expected in an ideal superlattice. The localization tendency can be substantially reduced by decreasing the barrier thickness and/or potential barrier height.
Multiple waveguide lens
Authors: Haus H. A. , Molter-Orr L. , Leonberger F. J.
Published: February 2003

Coupled optical waveguide systems that transform coherent excitations of N waveguides into an excitation in a single waveguide are proposed. Such waveguide systems coupled to coherent laser diode arrays could function to combine the power from the individual laser elements to produce a single spot.
Spatial concentrations of silicon atoms by laser-induced fluorescence in a silane glow discharge
Authors: Roth R. M. , Spears K. G. , Wong G.
Published: February 2003

A capacitively coupled, rf glow discharge of silane in argon was studied to determine the spatial concentration of silicon atoms. Laser-induced fluorescence was used to determine the ground state concentration profiles. The fluorescence profiles clearly show the sharp boundaries of the sheath regions. These profiles were much more sensitive to plasma chemistry changes than profiles obtained from plasma emission. Experiments with nitrogen addition demonstrated significant changes in the silicon atom profiles near the sheath boundary.
Optical recording in hydrogenated amorphous silicon
Authors: John P. , Jones B. L.
Published: February 2003

An archival optical storage technique based on hydrogen evolution in hydrogenated amorphous silicon (a-Si:H) is presented. Thin films (∼0.5 μm) of a-Si:H have been prepared by rf glow discharge in SiH4 and deposited on a thermally grown oxide pattern formed on float zone 〈111〉 crystalline Si (c-Si) substrates. Replication of the oxide pattern is achieved by ablation of the a-Si:H layer after annealing. This low-temperature process produces a predesigned array of circular holes caused by bursting of microbubbles in the a-Si:H layer. In comparison, the circular holes nucleate randomly on unoxidized c-Si.
Ni-Si(111) interface: Growth of Ni2Si islands at room temperature
Authors: van Loenen E. J. , Frenken J. W. M. , van der Veen J. F.
Published: February 2003

Ultrathin films (0–20 Å) of Ni have been deposited on atomically clean Si(111) surfaces at room temperature. The composition and morphology of the films have been determined, employing the high depth resolution obtainable in medium energy ion scattering. Disordered Ni2Si islands are formed, which grow laterally and in thickness with increasing Ni coverage. The silicide formation ends when the islands coalesce into a continuous film, at a Ni coverage of ≊8×1015 Ni atoms/cm2. During the silicide growth, the surfaces of the islands are rich in Si.
Photoluminescence from rapid thermal annealed and pulsed-laser-annealed, ion-implanted Si
Authors: Wagner J. , Gelpey J. C. , Hodgson R. T.
Published: February 2003

Low-temperature photoluminescence studies of ion-implanted and rapid thermal annealed or pulsed-laser-annealed Si are reported. The samples were implanted with As, P, Sb, or B. The luminescence spectra of the pulsed-laser-annealed samples show strong sharp luminescence lines from radiation induced defects, whereas in samples implanted with As, P, or B and rapidly annealed with an arc lamp a very clean spectrum without any defect luminescence is observed. This indicates a very low defect concentration in the lamp annealed material. In Sb-implanted lamp-annealed samples, however, a broad defect luminescence band appears as the temperature is raised and which varies in shape as a function of the annealing temperature. This band is probably due to Sb agglomerates.
Discontinuous/continuous metal films grown on photosensitive glass
Authors: Trotter D. M. , Smith D. W.
Published: February 2003

A new effect which allows direct formation of thin metal films of controlled morphology is described. Patterns of glass-ceramic opal are developed in photosensitive glass samples by UV irradiation and heat treatment. The samples are then ion exchanged in molten salt baths containing Ag+ or Cu+ ions. On subsequent firing in a hydrogen atmosphere, continuous films with typical thin metal films properties grow on the opal regions of the samples. Discontinuous films, characterized by activated resistivities and switching, grow on the glassy regions.
Use of transient capacitance measurements for direct determination of minority-carrier lifetime in low-doped metal-oxide-semiconductor structures
Authors: Efron U. , Braatz P. O.
Published: February 2003

A new method for the direct determination of minority-carrier lifetime is presented, which utilizes transient capacitance measurements performed with varying depletion voltages on metal-oxide-semiconductor (MOS) structures. It is shown that the slope of the fill (storage) time versus the depletion voltage is directly proportional to the minority-carrier lifetime. Good agreement is shown between results obtained with the proposed method and those obtained using a standard technique. The method is limited, however, to low-doped MOS structures which can be depleted to the back contact.
Magnetocrystalline anisotropy of R2Fe14B tetragonal compounds
Authors: Yamamoto H. , Matsuura Y. , Fujimura S. , Sagawa M.
Published: February 2003

A systematic study of magnetocrystalline anisotropy of R2Fe14B tetragonal compounds with various rare-earth elements (R) has been carried out at room temperature by the pulse method. The anisotropy fields of Y2Fe14B and Nd2Fe14B compounds are 3.1 and 12 MA/m, respectively. The maximum anisotropy field of 28 MA/m was observed in Tb2Fe14B compounds. The change in lattice parameters, saturation magnetization, and the Curie temperature with the rare-earth elements of R2Fe14B compounds is also described.
Spectral sensitization in an organic p-n junction photovoltaic cell
Authors: Harima Yutaka , Yamashita Kazuo , Suzuki Hitomi
Published: February 2003

Electric and photovoltaic characteristics of an orgainic p-n junction photovoltaic cell are described, where the p-type and n-type compounds used are phthalocyaninatozinc (II) (ZnPc) and 5, 10, 15, 20 -tetra (3-pyridyl) porphyrin (TPyP), respectively. The p-n junction cell with a thin film of TPyP exhibited stronger spectral sensitization and better spectral match to a solar spectrum than the Schottky barrier cells using either TPyP and ZnPc. The energy conversion efficiency found was about 2% for monochromatic light at 430 nm.
Staggered-lineup heterojunctions as sources of tunable below-gap radiation: Experimental verification
Authors: Caine E. J. , Subbanna S. , Kroemer H. , Merz J. L. , Cho A. Y.
Published: February 2003

We report experimental verification of the prediction of widely bias-tunable below-gap luminescence, from lattice-matched (p) (Al,In)As/ (n) InP heterojunctions, a system that has been predicted to have staggered lineup. The diodes, grown by molecular beam epitaxy, exhibit strong luminescence at 1.4 K, with a peak energy that shifts from 0.97 to 1.04 eV as the (pulsed) current density is increased from 4.5 to 40 A/cm2. Nonshifting injection luminescence at 1.4 eV, due to hole injection into the n-InP substrate, was also present, but appreciably weaker (<25%) than the interface luminescence. The spectra indicate that the band lineup in the (Al,In)As/InP system is indeed staggered, with a residual gap at the interface close to 0.96 eV. The corresponding conduction and valence-band offsets are 0.52 and 0.40 eV.
Electroabsorption spectroscopy of well and barrier materials in amorphous semiconductor superlattices
Authors: Roxlo C. B. , Abeles B. , Persans P. D.
Published: February 2003

Electroabsorption spectra of well and barrier regions have been separately determined in hydrogenated amorphous silicon/silicon carbide superlattices by taking advantage of built-in electric fields. Significant energy shifts are observed in materials with thin (<40 Å) layers. The data are consistent with a quantum size effect in the wells and substantial tunneling into the barriers, as predicted by a simple Kronig–Penney model.
A new, highly multiplexable liquid crystal display
Authors: Scheffer T. J. , Nehring J.
Published: February 2003

A new, highly multiplexable liquid crystal display is described, which has a superior image quality than a twisted nematic display multiplexed at the same high level. The display cell consists of a chiral-doped nematic layer with tilted boundaries and a twist angle of ∼270°. It operates in a birefringent optical mode between two ‘‘nonconventionally’’ oriented polarizers. Performance characteristics presented for a 120×240 dot matrix panel multiplexed at a 1/120 duty cycle include driving voltages compatible with complementary-metal-oxide-semiconductor technology, 300-ms response times, a contrast ratio of 10:1 at normal incidence, and ≥4:1 inside a viewing cone of 45° from the vertical.
Measurement of small elastic anisotropy in solids using laser-induced ultrasonic pulses
Authors: Tam A. C. , Leung W. P.
Published: February 2003

Nondestructive laser-induced short ultrasonic pulse generation (duration ≊10 ns) together with broadband detection is used to detect and measure the small elastic anisotropy in opaque solids quickly and precisely. This is demonstrated for an extruded aluminum alloy type 6061-T6. A single laser-induced acoustic pulse propagation measurement over a path length of 47 mm provides a longitudinal ultrasonic velocity measurement accuracy of 0.02%. The longitudinal velocities at ±45° from the extruding direction Z are found to be 2% larger than the velocity along Z, indicating that most of the aluminum crystallites are oriented with a principal axis parallel to Z. Thermal annealing of the sample results in a small increase in ultrasonic veolcity in all directions with the observed acoustic anisotropy remaining essentially unchanged.
Current distribution in a plasma erosion opening switch
Authors: Weber B. V. , Commisso R. J. , Meger R. A. , Neri J. M. , Oliphant W. F. , Ottinger P. F.
Published: February 2003

The current distribution in a plasma erosion opening switch is determined from magnetic field probe data. During the closed state of the switch the current channel broadens rapidly. The width of the current channel is consistent with a bipolar current density limit imposed by the ion flux to the cathode. The effective resistivity of the current channel is anomalously large. Current is diverted to the load when a gap opens near the cathode side of the switch. The observed gap opening can be explained by erosion of the plasma. Magnetic pressure is insufficient to open the gap.
Ablation scaling in steady-state ablation dominated by inverse-bremsstrahlung absorption
Authors: Ng A. , Pasini D. , Celliers P. , Parfeniuk D. , Da Silva L. , Kwan J.
Published: February 2003

The dependence of mass ablation rate and ablation pressure on laser wavelength and intensity have been measured for planar aluminum targets irradiated with 0.27-, 0.35-, and 0.53-μm laser pulses of 2-ns full width at half-maximum and at irradiances of 1012–5×1013 W/cm2. Target absorption is dominated by inverse bremsstrahlung and the ablative flow is steady state. The results show good agreement with theory modified by the steepening of the plasma density gradient for decreasing laser wavelength.
Characteristics of compressional shocks resulting from picosecond heating of confined foils
Authors: Schoen P. E. , Campillo A. J.
Published: February 2003

Multikilobar shocks were generated in thin foils of copper using picosecond duration 1.054-μm laser pulses (1–10 J/cm2) to create plasmas in the region between the front surface and an overlying glass window. Michelson interferometry was used to optically probe the particle velocity history of the rear foil surface, from which the magnitude and temporal profile of the shock pressure were deduced. The pressure dependence on fluence was observed to be linear and the temporal profile of the wave has a rapid rise and a tail which followed a t−1/2 dependence, consistent with a simple model.
Fiber-optic laser Doppler velocimeter using an external-cavity semiconductor laser
Authors: Kyuma Kazuo , Tai Shuichi , Nunoshita Masahiro , Nakayama Takashi
Published: February 2003

Influence of the spectral linewidth Δν of a semiconductor laser on the performance of a fiber-optic laser Doppler velocimeter (FLDV) was investigated. By using an external-cavity laser with Δν≂0.3 MHz, we could build a FLDV having an optical fiber probe length up to 25 m long.
Thermomigration in indium films
Authors: van Gurp G. J. , de Waard P. J. , du Chatenier F. J.
Published: February 2003

Thermomigration in indium films of thickness 0.5–3 μm was studied between 94 and 145 °C in a scanning electron microscope, using a 10-μm-wide Mo heater underneath the In. Transport was from hot to cold. The amount of transported In was determined by measuring the size of the holes appearing in the In above the heater. The activation energy is 0.8 eV. The transport starts after an incubation time and is faster for thinner films, probably because of grain boundary diffusion.
Structural and electrical properties of BF+2 implanted, rapid annealed silicon
Authors: Lunnon M. E. , Chen J. T. , Baker J. E.
Published: February 2003

A comparison has been made between ion implantation damage, implanted impurity profiles, and the dopant electrical characteristics in silicon implanted with boron fluoride and rapid annealed. The rapid anneal is accompanied by outdiffusion of fluorine except in regions containing residual implantation damage in the form of dislocation loops. During the anneal the boron dopant becomes electrically activated.
Enhanced Raman scattering from cesium suboxides on silver particles and the structure of S-1 photocathodes
Authors: Bates C. W.
Published: February 2003

Recent enhanced Raman scattering studies of cesium suboxides in S-1 photocathodes have indicated the presence of Cs11O3 but not Cs2O. The reason for the discrepancy between the currently accepted model of the S-1 and this recent result is discussed.
Raman study of structural transformations of titania coatings induced by laser annealing
Authors: Hsu L. S. , Solanki R. , Collins G. J. , She C. Y.
Published: February 2003

The first microscopic investigation of laser annealing of optical coatings is reported. Amorphous TiO2 coatings were ion sputtered onto Si wafers at room temperature. We show, using Raman spectroscopy, that upon laser annealing, the amorphous coatings were transformed into microcrystals of anatase structure at lower laser intensity and into a mixture of anatase and rutile structures at higher intensity.
GaAs lateral epitaxial growth over a tungsten grating by molecular beam epitaxy
Authors: Kondo Naoto , Kawashima Minoru , Ando Seigo , Oe Kunishige
Published: February 2003

GaAs lateral epitaxial growth over a tungsten grating is achieved by molecular beam epitaxy. Lateral overgrowth is seeded by epitaxial deposits formed on the GaAs (001) surface openings onto a line and space tungsten grating. The condition of obtaining continuous growth surface is investigated. While a rather slow growth rate (0.5 μm/h) results in faceted growth, a growth rate of 1 μm/h at a growth temperature of 730 °C on a 2.5-μm period tungsten grating of 〈110〉 direction permits one to obtain a smooth continuous overgrown layer. The x-ray diffraction pattern on this layer exhibits a single crystalline GaAs (400) pattern and an interface between the buried tungsten and the overgrown layer shows a preferable Schottky characteristic.
Selective area growth of gallium arsenide by metalorganic vapor phase epitaxy
Authors: Ghosh C. , Layman R. L.
Published: February 2003

Selective epitaxial growth of GaAs on (100) substrates partially covered with SiO2 was achieved by metalorganic vapor phase epitaxy. Under certain conditions of growth in a vertical reactor which were with a substrate temperature of 680° and As/Ga molar ratio of 12, epitaxial growth of GaAs took place in the areas not covered with SiO2; under those conditions there was no deposition on the areas covered with SiO2. As the substrate temperature was lowered, speckles of polycrystalline GaAs were formed on SiO2. At a temperature of 620 °C continuous polycrystalline GaAs was formed on SiO2 while epitaxial growth took place in the windows.
Determination of the valence-band discontinuity between GaAs and (Al,Ga)As by the use of p+-GaAs-(Al,Ga)As-p−-GaAs capacitors
Authors: Arnold D. , Ketterson A. , Henderson T. , Klem J. , Morkoç H.
Published: February 2003

The valence-band discontinuity between GaAs and AlxGa1−xAs (0.3≪x≪1.0) was determined from measurements on p+-GaAs-(Al,Ga)As-p−-GaAs capacitors from current-voltage measurements as a function of temperature. It was found that thermionic emission dominated the conduction process in these structures for temperatures above 140 K and for low bias voltages. The barrier height was determined from the slope of ln(J/T2) vs l/T. From this, a valence-band discontinuity of 35% of the total direct band-gap (EgΓ) discontinuity, being independent of the mole fraction x, between GaAs and (Al,Ga)As was calculated. The corresponding value for the conduction-band discontinuity, 65%, is considerably lower than the commonly accepted value of 85%.
Static and dynamic zig-zag magnetic domains
Authors: Hamzaoui S. , Labrune M. , Puchalska I. B.
Published: February 2003

The zig-zag domains have been investigated in a static and dynamic state. The materials are NiCoP and CoTi amorphous films 0.15 μm and 0.12 μm thick with a low coercivity. The first part deals with the nucleation and stabilization process. In the second part is described the characteristic motion of the zig-zag boundaries. It occurs in a bias field applied along the hard direction with an ac field applied simultaneously along the easy axis.
Mössbauer effect studies of Nd2Fe14B and related melt-spun permanent magnet alloys
Authors: Pinkerton F. E. , Dunham W. R.
Published: February 2003

We report for the first time the 57Fe Mössbauer spectrum of the ternary phase Nd2Fe14B, a technologically important new compound which forms the basis for a new class of high performance light rare earth-iron permanent magnet materials. From single phase powders we deduce the hyperfine parameters of the iron sublattices in the Nd2Fe14B structure. Spectra of high-energy product ribbons obtained by a rapid quench process confirm that these permanent magnet materials are comprised predominantly of the Nd2Fe14B phase.
1.55-μm InGaAsP ridge waveguide distributed feedback laser
Authors: Temkin H. , Dolan G. J. , Olsson N. A. , Henry C. H. , Logan R. A. , Kazarinov R. F. , Johnson L. F.
Published: February 2003

Optical and modulation properties of ridge waveguide distributed feedback lasers grown by liquid phase epitaxy and operating in the spectral region of 1.51–1.58 μm have been investigated. These lasers were characterized by room temperature cw threshold currents as low as 40 mA, external quantum efficiency of up to 40%, and lowest order transverse mode operation up to 10 mW. Stable, single longitudinal mode operation under direct modulation of up to 4 GHz was obtained using second order gratings fabricated by electron beam writing as well as optical holography. The absence of partition mode events has allowed routine error free transmission over 60 km of single mode fiber at data rates of 2 Gb/s. The relationship between grating parameters and the Bragg length has been studied experimentally and compared with the theoretical results.
Traveling-wave electro-optic modulator with maximum bandwidth-length product
Authors: Becker R. A.
Published: February 2003

A traveling-wave Ti-indiffused LiNbO3 guided-wave Mach–Zehnder interferometric modulator has been fabricated and characterized at λ=0.85 μm. The modulator achieves the theoretical 3-dB linear small-signal bandwidth limit of 16 GHz for a 4-mm-long interaction length. With a ±2.25-V drive signal, an extinction ratio of 22 dB is achieved. Linear small-signal measurements made with a swept-frequency technique are compared to previously reported measurements.
Pseudo-quaternary GaInAsP semiconductors: A new Ga0.47In0.53As/InP graded gap superlattice and its applications to avalanche photodiodes
Authors: Capasso F. , Cox H. M. , Hutchinson A. L. , Olsson N. A. , Hummel S. G.
Published: February 2003

We have demonstrated for the first time a pseudo-quaternary GaInAsP semiconductor consisting of a graded gap Ga0.47In0.53As/InP superlattice. The average composition and the band gap of this structure are spatially varied by gradually changing the thicknesses of the InP and Ga0.47In0.53As layers between 5 and 55 Å while keeping constant the period of the superlattice (=60 Å). This new graded gap superlattice has been used to eliminate the interface pile-up effect of holes in a ‘‘high-low’’ InP/Ga0.47In0.53As avalanche photodiode, without requiring the growth of a separately lattice-matched Ga1−xInxAs1−yPy layer. High-speed operation at 1.7 Gb/s and λ=1.55 μm has been achieved. Pseudo-quaternary semiconductors represent a new technique of growing GaInAsP and can conveniently replace conventional Ga1−xInxAs1−yPy alloys in a variety of device applications.
Reduction of electron and hole trapping in SiO2 by rapid thermal annealing
Authors: Weinberg Z. A. , Young D. R. , Calise J. A. , Cohen S. A. , DeLuca J. C. , Deline V. R.
Published: February 2003

Reduction of electron or hole trapping in SiO2 was achieved by short-time lamp annealing. The trapping characterization was done by the avalanche injection technique on metal-oxide-silicon capacitor structures with aluminum gates and SiO2 thickness of 50 nm. Electron trapping on water related centers is reduced by 10-s anneals in Ar or N2 ambients at 600–800 °C. Hole trapping is reduced by short anneals in an O2 ambient at 1000 °C with an optimal time of 100 s. The O2 short anneal is much more effective if the oxide had a long post-oxidation anneal in N2 at 1000 °C which produces an interfacial nitrogen-rich layer at the Si-SiO2 interface.
Room-temperature annealing of radiation-induced defects in InP solar cells
Authors: Yamaguchi Masafumi , Itoh Yoshio , Ando Koushi
Published: February 2003

Observation of effective room-temperature annealing of radiation-induced defects in InP is reported. By maintaining InP solar cells at room temperature (277–295 K), defect annealing in both p-type and n-type InP after electron irradiation is found, which results in the recovery of InP solar cell properties. The recovery on InP solar cell properties is found to be due to room-temperature annealing of radiation-induced minority-carrier deep trap in the substrate layer. These results suggest that InP solar cells have better radiation hardness characteristics than Si or GaAs solar cells.
Evidence for nonuniform flow of charge carriers through semiconductor junctions
Authors: Tenne R. , Marcu V. , Yellin N.
Published: February 2003

Photoelectrochemical etching (photoetching) of many semiconductors leads to a pitted morphology with small etch pits (>109 cm−2) uniformly distributed over the entire semiconductor surface. It is shown here that the etch pit density increases with doping density and decreases with forward bias. These results suggest that charge flow within semiconductor junctions is highly nonuniform due to the existence of microscopic electric fields induced by the ionized donors within the space-charge layer. Numerical results for a set of CdSe and CdTe crystals are reported.
Photoluminescence of GaAs single quantum wells confined by short-period all-binary GaAs/AlAs superlattices
Authors: Fujiwara Kenzo , Ploog Klaus
Published: February 2003

GaAs single quantum well heterostructures (SQWH’s) composed of all-binary AlAs/GaAs heterostructures by using AlAs/GaAs short-period superlattices (SPS) instead of the ternary alloy as cladding layers were grown by molecular beam epitaxy at low substrate temperature. Detailed photoluminescence measurements at 2 K reveal that these SPS confined SQWH’s exhibit superior luminescence properties. They are therefore very attractive for application in new optoelectronic devices. The SPS configuration has a strong effect on the energy of the confined particle transition because of the fully interacting quantum well system.
Electrical properties of implanted and rapid thermal annealed shallow p+-n junctions
Authors: Ozguz V. H. , Wortman J. J. , Hauser J. R. , Simpson L. , Littlejohn M. A. , Chu W. K. , Rozgonyi G. A.
Published: February 2003

The electrical properties of shallow junctions fabricated using a 50-keV BF2 ion implantation into 〈100〉 n-Si followed by rapid thermal annealing (RTA) have been investigated. The junction depth was 0.25 μm. Sheet resistance measurements have shown that annealing at 950 °C for only 10 s results in approximately 90% electrical activation. In addition this annealing cycle gives the optimum leakage current. The leakage current density obtained was 1 fA/μm2 (at 10-V reverse bias voltage, for 2–4-Ω cm n-type substrate). The results indicate that RTA can be used to obtain reproducible shallow junctions without significantly changing the implanted profile.
Electrical characterization of Fe-doped semi-insulating InP grown by metalorganic chemical vapor deposition
Authors: Macrander A. T. , Long J. A. , Riggs V. G. , Bloemeke A. F. , Johnston W. D.
Published: February 2003

The bulk resistivity of Fe-doped metalorganic chemical vapor deposited grown epitaxial InP was determined from current-voltage and capacitance measurements made on Schottky-diode-like devices. The current-voltage data exhibit both an ohmic and a space-charge-limited regime, and the capacitance was found to be independent of applied bias. The electrical thickness was obtained from the capacitance using a relationship appropriate for current injection. Data for two samples representing both thin (∼1 μm) and thick (∼9 μm) epitaxial layers are presented. The resistivities were 6.5×107 Ω cm and 2.2×108 Ω cm.
Effect of doping level on the gain constant and modulation bandwidth of InGaAsP semiconductor lasers
Authors: Su C. B. , Lanzisera V.
Published: February 2003

Using the threshold carrier density measurement technique, the differential gain dg/dn at lasing threshold was measured. It was found that the differential gain dg/dn of 1.3-μm InGaAsP lasers is a strong function of the active layer doping level P0. At a doping level of 2.5×1018 cm−3, the differential gain is several times larger than at 4×1017 cm−3. A factor of 2 increase in the modulation bandwidth is demonstrated using the dg/dn dependency on P0.
High-speed modulation and switching with gain in a GaAlAs traveling-wave optical amplifier
Authors: Hegarty J. , Jackson K. A.
Published: February 2003

We demonstrate optical amplification of 10-ps-long pulses in a traveling-wave type GaAs double heterostructure laser diode. A continuous train of mode-locked pulses from a dye laser focused end on into the GaAs active region is amplified by a factor of 10 under injection by a synchronous train of current pulses and attenuated by a factor of 10 in the absence of current injection. This gives a switch/modulator with modulation depths of 100, overall gain, and measured switching speed of many GHz. A cw beam can be modulated at similar gains and speeds and since the device is capable of integration the performance of many optical functions without loss is possible.
Plasma etching in magnetic multipole microwave discharge
Authors: Arnal Y. , Pelletier J. , Pomot C. , Petit B. , Durandet A.
Published: February 2003

A plasma etching reactor is described which associates surface magnetic confinement, microwave discharge, and independently controlled substrate biasing. Preliminary measurements show that the reactor produces reactive plasmas allowing anisotropic fine line etching at low ion energy.
Effects of impurities on the oxidation of MoSi2 on silicon
Authors: Wakita A. S. , Sigmon T. W. , Gibbons J. F.
Published: February 2003

When MoSi2 films on silicon are exposed to oxidizing ambients, a continuous layer of SiO2 grows on the silicide surface. However, when the presence of oxygen impurities exceeds 2 at. % at the silicon-MoSi2 interface, metal-rich silicide phases form. The coexistence of these phases and the absence of metal oxides are explained by considering both the oxidation kinetics and the ternary phase diagram of the Mo-Si-O system.
Polycrystalline CdS photocorrosion studied by capacitance and action spectra measurements
Authors: Dewitt R. , Kirsch-De Mesmaeker A.
Published: February 2003

Polychromatic illumination of polycrystalline CdS films in contact with basic aqueous solutions of 1 M cysteine increases the photocurrent as a function of time. It is shown that the evolution of the photocurrent spectra and Mott–Schottky plots, recorded as a function of the illumination time, is in agreement with the formation of a mixed film CdS1−xOx at the surface, leading eventually to an amorphous CdO layer.
12% solar conversion efficiency by interphase restructuring
Authors: Menezes Shalini
Published: February 2003

Solar energy conversion efficiency of n-CuInSe2/p-CuISe3 heterojunction formed in situ and contacted by I−-I2-Cu+-HI electrolyte has been increased to 12% by modifying the growth conditions of the p-CuISe3 phase. These include the use of prepolished n-CuInSe2 (110) surfaces, higher concentrations of HI and Cu+, and an air anneal at 200 °C. X-ray fluorescence analysis in conjunction with scanning electron micrographs of the new interphase indicates structural and compositional alterations and possibly further transformation of CuISe3 to CuIn2Se3I. Temperature dependence of the cell performance indicates solid state effects and relative independence of electrochemical kinetics.
Molecular beam epitaxial growth of InGaP/InAlP quantum well structures for the visible wavelength region
Authors: Kawamura Y. , Asahi H.
Published: February 2003

InGaP InAlP quantum well structures for the visible wavelength region have been grown by molecular beam epitaxy for the first time. The formation of the superlattice structure was confirmed for the multiquantum well structure wafer by double crystal x-ray diffraction measurement and sputtering Auger electron measurement. Photoluminescence measurement at 77 K on the multilayer structure wafer with different thickness InGaP well layers showed that quantum levels were formed in InGaP well layers.
Thermal radiation from laser heated silicon and pyrometric temperature measurements
Authors: Kemmler M. , Wartmann G. , von der Linde D.
Published: February 2003

We report time-resolved measurements of thermal radiation during laser heating of silicon using 10-ns laser pulses. The data provide further evidence that the laser-induced high reflectivity phase is due to melting of the surface. From thermal emission spectra the evolution of the surface temperature for both the crystalline and the liquid state is obtained.
Infrared excitation spectrum of 40.4-meV acceptor level in neutron-irradiated gallium-doped silicon
Authors: Fischer David W. , Mitchel W. C.
Published: February 2003

An infrared absorption spectrum has been obtained for the shallow A2 acceptor level formed by neutron irradiation of Si:Ga. After a 600 °C anneal, absorption peaks were observed at 213.1, 244.9, and 286.9 cm.−1 These peaks appear to correspond to lines 1, 2, and 4 of a group III-like acceptor spectrum originating from a ground state with a 40.4-meV binding energy. Hall effect measurements confirm the presence of an acceptor level at this energy.
Synchrotron photoemission investigation: Fluorine on silicon surfaces
Authors: Morar J. F. , McFeely F. R. , Shinn N. D. , Landgren G. , Himpsel F. J.
Published: February 2003

High resolution core level photoemission spectroscopy has been used to obtain the first direct identification of the chemical species remaining on silicon surfaces after exposure to fluorine. Both Si(111) 2×1 and Si(111) 7×7 were exposed to fluorine via the dissociative chemisorption of XeF2. For fluorine coverages in the monolayer regime, SiF1, SiF2, and SiF3 were all present although their relative abundance varied significantly between the two surfaces. No evidence for the existence of unreacted interestitial fluorine was found. These results suggest the need for modification of current models describing plasma and reactive ion etching of silicon.
Dispersion of the refractive index of ternary compound Pb1−xSnxTe
Authors: Jensen B. , Torabi A.
Published: February 2003

The refractive index of Pb1−xSnxTe below the fundamental absorption edge is calculated as a function of photon energy and carrier concentration. Use of the band structure of the Kane theory results in a good agreement of theory with experiment. Numerical values of the refractive index for some values of x in the range 0≤x≤0.42 are given and discussed.
Breakdown in silicon oxides—correlation with Cu precipitates
Authors: Honda Kouichirou , Ohsawa Akira , Toyokura Nobuo
Published: February 2003

Thin oxides grown on silicon substrate in which Cu+ ions had been implanted before oxidation were studied by transmission electron microscope (TEM) and scanning TEM imaging methods. Cu precipitates, stacking faults, and dislocations appeared at the SiO2/Si interface on the degraded specimens. The Cu precipitates reduce the breakdown strength by local thinning of the oxide thickness. Stacking faults and dislocations, however, do not reduce the breakdown strength.
Optical approach to thermopower and conductivity measurements in thin-film semiconductors
Authors: Dersch Helmut , Amer Nabil M.
Published: February 2003

An optical beam deflection technique is applied to measure the Joule and Peltier heat generated by electric currents through thin-film semiconductors. The method yields a spatially resolved conductivity profile and allows the determination of Peltier coefficients. Results obtained on doped hydrogenated amorphous silicon films are presented.
Semiconductor properties of polyphosphides
Authors: Schachter R. , Michel C. G. , Kuck M. A. , Baumann J. A. , Olego D. J. , Polgar L. G. , Raccah P. M. , Spicer W. E.
Published: February 2003

For the first time, the electro-optical properties of nontetrahedrally bonded crystalline and amorphous polyphosphides have been investigated. The crystalline archetype KP15 is a high resistivity semiconductor, with photoconductivity and photoluminescence at the band gap (1.7 eV). These measurements are extended to amorphous films prepared by vapor transport methods. The resistivity of the films has been varied over eight orders of magnitude by the incorporation of 0%–2% Ni. Nonlinear metal-semiconductor behavior with good current carrying capability (1 A/cm2) has been observed. When deposited on InP, the films reduce the density of surface states in metal-insulator-semiconductor diodes to ∼1010/cm2 eV, probably by providing continuity to the group V element at the interface. It is concluded that the low crystal symmetry of polyphosphides leads to a significant new amorphous semiconductor in which the electronic coherence length is commensurate with the intermediate range order.
Role of the piezoelectric effect in device uniformity of GaAs integrated circuits
Authors: Chang M. F. , Lee C. P. , Asbeck P. M. , Vahrenkamp R. P. , Kirkpatrick C. G.
Published: February 2003

In order to assess the orientation dependence of device uniformity in GaAs integrated circuits, metal-semiconductor field-effect transistors (MESFET’s) were fabricated along different crystal orientations on a 3-in. (100) substrate and compared with one another. Measurements indicated that the characteristics of FET’s oriented along [011] and [011̄] directions have strong dependence upon their radial positions on the wafer. However, FET’s oriented in [001] and [010] directions do not display such dependence and have better device uniformity. The orientation effect on the radial dependence of the FET device characteristics can be attributed to the piezoelectric effect.
High power output, low threshold, inner stripe GaInAsP laser diode on a p-type InP substrate
Authors: Imanaka K. , Horikawa H. , Matoba A. , Kawai Y. , Sakuta M.
Published: February 2003

A V-grooved, inner stripe laser diode on a p-type InP substrate emitting at 1.3 μm is reported. The maximum cw output power of 65 mW and the threshold current of 15 mA with fundamental transverse mode operation are performed. The laser has high differential quantum efficiency of 70% at 20 °C and is stably operated at high temperatures; output power >20 mW at 80 °C. The dependence of the threshold current density on the doping impurity level of zinc in the active layer is also discussed.
Effects of water vapor on modes in Ti-indiffused LiNbO3 planar waveguides
Authors: Forouhar S. , Betts G. E. , Chang W. S. C.
Published: February 2003

We report two observations concerning the addition of water vapor to the O2 gas flowing during Ti indiffusion in LiNbO3. (1) Outdiffusion is not completely suppressed (e.g., at 1100 °C an out-diffused mode occurs after 40 min when the flowing gas is 85% H2O). (2) Water vapor has an effect on the indiffused modes that is not due to suppression of outdiffusion. We compare planar guides diffused in dry O2, wet O2, and LiNbO3 powder to show this effect. Our data support the hypothesis that water vapor reduces the Ti diffusion constant (∼9×10−13 cm2/s with <3% H2O, ∼4×10−13 cm2/s with 85% H2O, at 1000 °C).
On the origin of the long-wavelength loss anomaly in H2-treated germano-phospho-silicate glass fibers
Authors: Stone J. , Burrus C. A. , Wiesenfeld J. M.
Published: February 2003

We show, by isotopic substitution OH→OD, that the added loss beyond 1.3 μm in optical fibers when treated in H2 at 200 °C is OH absorption. It consists of a peak around 1.4 μm which is OH overtone absorption and a monotonic increase beyond 1.5 μm which is the wing of the OH fundamental absorption. The amount of OH fundamental absorption due to H2 at 200 °C is much smaller for a P-doped silica glass than for a Ge-P-doped glass.
Optical-optical guided-wave modulator
Authors: Yajima H. , Sudo E. , Yumoto J. , Kashiwa K.
Published: February 2003

An amorphous silicon photovoltaic detector was integrated on the LiNbO3 interferometric waveguide type guided-wave modulator, and guided-wave modulation by an external He-Ne laser light was demonstrated with a time response of 5 μs.
All-optical remote monitoring of propane gas using a 5-km-long, low-loss optical fiber link and an InGaP light-emitting diode in the 1.68-μm region
Authors: Chan Kinpui , Ito Hiromasa , Inaba Humio
Published: February 2003

We report the fully optical remote detection of low-level propane (C3H8) gas realized by the scheme based on a long distance, very low-loss silica optical fiber link connected to a compact absorption cell in conjunction with a high radiant InGaP light-emitting diode at 1.68 μm. For this application, the near-infrared absorption spectrum of propane was measured and studied to find very complicated bands around 1.69, 1.53, and 1.38 μm. This simple system, employing a 5-km-long silica optical fiber link, was demonstrated to be capable of achieving reproducibly the detection sensitivity less than 2.4 Torr for propane gas in air, i.e., about 14% of the lower explosion limit of propane density. This result verifies a large capability for major applications to various strategic points within the environment, such as industrial complexes as well as urban and residential areas, with considerably increased reliability and safety over the existing techniques.
Depth profiles of perpendicular and parallel strain in a GaAsxP1−x/GaP superlattice
Authors: Speriosu V. S. , Nicolet M.-A. , Picraux S. T. , Biefeld R. M.
Published: February 2003

Using double-crystal x-ray rocking curves, depth profiles of parallel and perpendicular strain were obtained in a GaAs0.14P0.86/GaP superlattice grown on a buffer layer on (100) GaP. Combining symmetric Fe Kα1 (400) and asymmetric Cu Kα1 (422) reflections, a constant parallel strain of 0.19% relative to the substrate was found throughout the superlattice and buffer layer. Relative to the substrate, the perpendicular strain was found to be 0.26% in the buffer, and 0.80% and −0.19% in the 176-Å-thick superlattice GaAsxP1−x and GaP layers, respectively. The strain profiles indicate the buffer is ∼80% decoupled from the substrate by misfit dislocations near the buffer/substrate interface, and the lattice misfit in the superlattice is elastically accommodated by the epitaxial structure with a small shift in the average lattice constant relative to the equilibrium superlattice structure.
Observation of enhanced emission of the O VIII Hα line in a recombining laser-produced plasma
Authors: Matthews D. L. , Campbell E. M. , Estabrook K. , Hatcher W. , Kauffman R. L. , Lee R. W. , Wang C. L.
Published: February 2003

We have observed enhanced emission of the O VIII Hα line at 121 eV from a recombining plasma produced by laser heating of a thin Formvar foil with two opposed cylindrically focused (0.3×1.4 cm) 5-TW laser beams. The time-dependent intensity of the Hα line increases by nearly an order of magnitude as the plasma length is increased from 0.27 to 1.27 cm. This increase in intensity is greater than that expected from a medium exhibiting no gain. A comparison of the measured time history of the emission with that of non-local thermodynamic equilibrium time-dependent calculations suggests that a small-signal gain ∼0.5 cm−1 is obtained.