bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of a microwave plasma disk ion source
Authors: Asmussen Jes , Root Joseph
Published: February 2003

This letter describes an ion source using a cylindrical microwave cavity operating in a hybrid mode associated with the TE211 empty cavity mode. The design principles and associated electrical systems are also discussed. Extracted beam current versus accelerating voltage, and specific energy versus extracted beam current are displayed over the range of flow rates 20–80 sccm and absorbed powers 80–150 W. The results show the feasibility of this concept. The ion source has many potential uses such as space propulsion, material processing, and neutral beam ion sources.
Channeling in low energy boron ion implantation
Authors: Michel A. E. , Kastl R. H. , Mader S. R. , Masters B. J. , Gardner J. A.
Published: February 2003

The effects of both planar and axial channeling on the profile of 5-keV boron ions implanted into (100) oriented silicon wafers are demonstrated. A tilt angle of 12° from the (100) axis in a ‘‘random’’ crystallographic direction is required to minimize the (100) axial channeling tail. It is also shown that the effect of channeling along 100 planar channels produces a negligible addition to the channeling tail, whereas channeling along the (110) planar channels produces a measurable contribution. Implantation through a thin, 8-nm, thermally grown silicon dioxide layer with the ion beam aligned along the (100) direction produces an ion profile comparable to an offset of 9° in a random direction.
Raman microprobe determination of local crystal orientation in laser annealed silicon
Authors: Hopkins J. B. , Farrow L. A. , Fisanick G. J.
Published: February 2003

In this letter we discuss the application of polarization selective Raman microprobe spectroscopy to the detailed, nondestructive analysis of the local crystal orientation of a polycrystalline silicon sample grown over SiO2 pads and laser annealed. Intensity measurements taken as a function of input polarization angle are fit to an expression derived from the Raman scattering selection rules to calculate the angles by which the crystal structure is twisted within the original substrate plane, as well as the degree of tipping of the crystal plane away from the plane of the Si substrate.
Optical stethoscopy: Image recording with resolution λ/20
Authors: Pohl D. W. , Denk W. , Lanz M.
Published: February 2003

Subwave length-resolution optical image recording is demonstrated by moving an extremely narrow aperture along a test object equipped with fine-line structures. Details of 25-nm size can be recognized using 488-nm radiation. The result indicates a resolving power of at least λ/20 which is to be compared with the values of λ/2.3 obtainable in conventional optical microscopy.
Laser produced plasma in crystalline α-Al2O3 and aluminum metal
Authors: Rothenberg Joshua E. , Koren Gad
Published: February 2003

A comparative study of the laser produced plasma (LPP) in vacuum at the surface of transparent crystalline α-Al2O3 (sapphire) and Al metal generated by 248-nm excimer laser pulses of 15-ns duration is reported. It was found that the threshold fluence for strong LPP emission in sapphire is 0.55 J/cm2, which is significantly lower than that needed for the same process in clean Al (1.7 J/cm2). At fluences higher than 4 J/cm2 the LPP emission from both targets is similar. The results obtained in sapphire require that its absorption coefficient increase by many orders of magnitude during the laser pulse. A possible explanation for the observed threshold difference is that the greater thermal diffusivity of Al more than compensates for its greater volatility; hence, a greater fluence is necessary to create the LPP in Al.
Theory of photoluminescence line shape due to interfacial quality in quantum well structures
Authors: Singh Jasprit , Bajaj K. K. , Chaudhuri S.
Published: February 2003

We have developed a simple theory to understand the role of interfacial quality in the line shape of photoluminescence spectra in quantum wells. The interface is described in terms of microscopic fluctuations δ1 and δ2, where δ1 is the local fluctuation in the well width and δ2 is the lateral correlated extent of the fluctuation. We make use of Lifshitz theory of disordered alloys to determine the probability of distribution of fluctuations in the well size over the extent of the optical probe, i.e., the exciton. The line shape is then calculated from this probability distribution. Both δ1 and δ2 are found to be important in controlling the linewidths in quantum wells. The use of this quantitative theory to characterize the microscopic nature of interfaces is discussed.
80× single-stage compression of frequency doubled Nd:yttrium aluminum garnet laser pulses
Authors: Johnson A. M. , Stolen R. H. , Simpson W. M.
Published: February 2003

Single-stage compression factors as high as 80× have been demonstrated for the 0.532-μm optical pulses of a frequency doubled Nd:yttrium aluminum garnet laser using a single-mode fiber and a modified grating-pair delay line. Input optical pulses of 33-ps duration have been compressed to 0.41-ps duration. This represents the largest single-stage compression factor reported to date. Subpicosecond optical pulses can be obtained directly from relatively long optical pulses without the use of a mode-locked dye laser.
Laser induced metal deposition from organometallic solution
Authors: Yokoyama H. , Kishida S. , Washio K.
Published: February 2003

Solutions of bisbenzene metals in organic solvents have been used for the first time to produce localized deposition of metals on a glass substrate by laser induced pyrolysis. Molybdenum and chromium spots, as small as 10 μm in diameter, were obtained by using an argon-ion laser at several tens of milliwatt power.
Bulk nucleation and amorphous phase formation in highly undercooled molten silicon
Authors: Wood R. F. , Lowndes D. H. , Narayan J.
Published: February 2003

Solidification of undercooled liquid (l) Si formed by pulsed laser melting of amorphous (a) layers has been studied experimentally and theoretically. Bulk nucleation apparently occurs at a temperature higher than that of the l→a phase transition. Release of latent heat on nucleation is crucial in determining the depth of melting. It is emphasized that bulk nucleation implies that the l→a transition cannot be explained by purely thermodynamic considerations.
Below band-gap photoluminescence of Hg1−xCdxTe
Authors: Polla D. L. , Aggarwal R. L.
Published: February 2003

We have applied the technique of below band-gap photoluminescence to the narrow gap semiconductor Hg0.7Cd0.3Te. A single peak in the observed photoluminescence spectra for liquid phase epitaxial samples has been interpreted as being due to a spontaneous transition from a deep donor level at approximately 0.4Eg to the valence band. The energy associated with this photoluminescence peak corresponds closely to deep level activation energies obtained by both optical modulation spectroscopy and thermally excited relaxation characterization techniques.
Nonlinear waves guided by thin films
Authors: Stegeman George I. , Seaton Colin T. , Chilwell John , Smith S. Desmond
Published: February 2003

The dispersion relations for waves guided by thin dielectric films surrounded on one or both sides by media with intensity-dependent refractive indices are solved numerically. A number of new modes as well new features in the usual low power modes are predicted.
Generation and measurement of optical pulses as short as 16 fs
Authors: Fujimoto J. G. , Weiner A. M. , Ippen E. P.
Published: February 2003

We describe measurements of pulses consisting of only eight optical periods. The pulses were produced by compression with a short optical fiber and a grating pair. Measurement was by autocorrelation using noncollinear second harmonic generation in a thin crystal of potassium dihydrogen phosphate.
High-temperature electrical properties of 3C-SiC epitaxial layers grown by chemical vapor deposition
Authors: Sasaki K. , Sakuma E. , Misawa S. , Yoshida S. , Gonda S.
Published: February 2003

Electrical properties of 3C-SiC layers, epitaxially grown on silicon by chemical vapor deposition, have been investigated at the temperatures between room temperature and 850 °C. In this temperature range, the electron mobility changes with temperature as μH∼T−1.2∼−1.4. The weaker temperature dependence of mobility and the larger mobilities compared with other polytypes of SiC suggest that 3C-SiC is a promising material for devices operated at high temperatures.
Novel hybrid optically bistable switch: The quantum well self-electro-optic effect device
Authors: Miller D. A. B. , Chemla D. S. , Damen T. C. , Gossard A. C. , Wiegmann W. , Wood T. H. , Burrus C. A.
Published: February 2003

We report a new type of optoelectronic device, a self-electro-optic effect device (SEED), which uses the same GaAs/GaAlAs multiple quantum well material simultaneously as an optical detector and modulator. Using a series resistor and constant voltage bias supply the SEED shows optical bistabilty (OB) of the recently discovered type which relies on increasing absorption and requires no mirrors. OB is seen at room temperature from ∼850–860 nm, at powers as low as 670 nW or switching times as short as 400 ns (limited only by power restrictions) with ∼1-nJ optical switching energy in a 600-μm-diam device. Total energies per unit area (∼18 fJ/μm2) are substantially lower than any previously reported for OB.
Short wavelength (visible) GaAs quantum well lasers grown by molecular beam epitaxy
Authors: Woodbridge K. , Blood P. , Fletcher E. D. , Hulyer P. J.
Published: February 2003

GaAs-AlGaAs multiple quantum well (MQW) injection lasers with well widths from 55 to 13 Å have been grown by molecular beam epitaxy and operated at room temperature, showing emission at wavelengths down to 704 nm, the shortest reported for a MQW injection laser with GaAs wells. In a device with 25-Å wells some evidence of coupling was apparent when barrier widths were reduced to 40 Å. For devices with 80-Å barriers there is a difference of about 20 nm between the calculated n=1 (e–hh) transition wavelength and the lasing wavelength, whereas the calculation agrees with photovoltage absorption measurements on the same structures.
Operation of an ICl fueled oxygen-iodine chemical laser
Authors: Wiswall C. E. , Lilenfeld H. V. , Bragg S. L.
Published: February 2003

cw operation of a chemical oxygen-iodine laser (COIL) using ICl as a source of atomic iodine at powers approaching 120 W is reported. The vapor pressure of ICl is higher than the vapor pressure of the more conventional I2 fuel usually used in COIL. More iodine can therefore be delivered to the laser gas stream using ICl than can be delivered using I2. This concentration increase is advantageous for low-temperature operation at high partial pressures of the atomic iodine source.
Raman scattering from GexSi1−x/Si strained-layer superlattices
Authors: Cerdeira F. , Pinczuk A. , Bean J. C. , Batlogg B. , Wilson B. A.
Published: February 2003

Raman spectroscopy has been used to determine built-up deformation in GexSi1−x/Si strained-layer superlattice grown by molecular beam epitaxy. By comparing peak positions in commensurate superlattices and single layers with those from incommensurate thick layers of the same composition we can obtain a quantitative determination of strain. Linewidths are affected by the presence of inhomogeneous strain, dislocations, and disorder. Lines are always narrower in superlattice samples, indicating better crystalline quality. In particular, the Raman line from the Si layers of the strained-layer superlattices is indistinguishable from that from single-crystalline Si in both linewidth and frequency. This is consistent with the expectation that the entire lattice mismatch is accommodated as a homogeneous tetragonal strain in the alloy layers only.
Column IIIA metal film deposition by dissociative photoionization of metal halide vapors
Authors: Geohegan D. B. , Eden J. G.
Published: February 2003

Films of column IIIA metals (In, Al, and Tl) have been deposited on several different substrates (stainless steel, nickel, copper, and silver) by dissociatively photoionizing the corresponding metal iodide in a uniform electric field. Thin (≲0.2 μm) indium films have been grown on nickel by photoionizing indium monoiodide (InI) vapor with an argon fluoride (ArF) excimer laser at 193 nm. A similar process has resulted in thallium films produced from thallium iodide (TlI) vapor with a high pressure xenon lamp.
Formation of multiatomic cluster ions of silicon in pulsed-laser stimulated field desorption
Authors: Tsong T. T.
Published: February 2003

Multiatomic cluster ions of 3 to ∼16 atoms/cluster are formed in pulsed-laser stimulated field absorption. Utilizing an isotope mixing which occurs in cluster formation, the most abundant cluster ion species are identified to be Si2+4, Si2+5, and Si2+6. Si4+13 is also found. These magic numbers, 4, 5, 6, and 13, correspond to the highly symmetric, small units of atoms existing in a Si crystal. The critical number of 2+ ions is found to be 3.
UV ozone cleaning of silicon substrates in silicon molecular beam epitaxy
Authors: Tabe Michiharu
Published: February 2003

This letter reports UV ozone cleaning of Si substrates for obtaining defect-free molecular beam epitaxial films by low-temperature in vacuum preheating. By using UV ozone cleaning, the high temperatures above 1200 °C required for removing surface carbon in the conventional method can be significantly lowered to below 1000 °C, since the UV ozone cleaning functions to remove carbon.
Low-noise Ga0.47In0.53As photoconductive detectors using Fe compensation
Authors: Chen C. Y. , Chi G. C.
Published: February 2003

We demonstrate a low-noise Ga0.47In0.53As photoconductive detector prepared by liquid phase epitaxy using Fe compensation. A carrier concentration as low as 1.8×1013 cm−3 and a Hall mobility as high as 5390 cm2/Vs have been achieved. This has improved the noise current by 3.7 dB but reduced the gain (∼15) by 4.8 dB as compared to a high-mobility undoped detector grown by vapor phase epitaxy. The Fe incorporation has resulted in a factor of 2 improvement in the fall time (∼1.2 ns), which will reduce the amount of equalization required and hence improve the dynamic range of the detector. When tested in a receiver circuit containing a GaAs field-effect transistor front end at 1 Gb/s, the detector (no AR coating) showed a receiver sensitivity of −30.3 dBm at 1.55 μm for a bit error rate of 10−9.
Influence of energy transfer in nuclear collisions on the ion beam annealing of amorphous layers in silicon
Authors: Holmén G. , Linnros J. , Svensson B.
Published: February 2003

Amorphous surface layers produced by ion bombardment in silicon on sapphire have been ion beam annealed at 300 °C. The annealing behavior has been found to be dependent on the part of the ion energy transferred in nuclear collisions.
A low leakage 10 000-V silicon photoconductive switch
Authors: Koo Jackson C. , McWright Glen M. , Pocha Michael D. , Wilcox Russel B.
Published: February 2003

Under high bias voltage, the leakage current through a silicon photoconductive switch is mainly caused by carrier injection at the metallic contacts. A low leakage, high voltage silicon photoconductive switch is fabricated by the introduction of carrier trap centers between the silicon substrate and metallic contacts. We report 2.5-mm gap photoconductive switches with leakage currents of less than 50 mA at a pulse bias of 10 kV for 600 ns, and an ‘‘on’’ resistance of less than 1.3 Ω, when illustrated by a 1-ns, 1000-μJ pulse of 1.05-μm radiation.
Hydrogen passivation of dislocations in silicon
Authors: Dubé C. , Hanoka J. I.
Published: February 2003

The electron beam induced current method has been used to show that the principal defects passivated by hydrogen in silicon ribbon grown by the edge-defined film-fed growth technique are, in fact, dislocations. Hydrogen diffusivity for dislocation arrays has been determined to be ≥10−8 cm2/s. It is shown that deep, intragranular passivation depths of up to 250 μm can occur by hydrogen diffusion along dislocation arrays. A model is proposed wherein grain boundary passivation is viewed as a special case of dislocation passivation.
Intermodulation distortion in a directly modulated semiconductor injection laser
Authors: Lau K. Y. , Yariv A.
Published: February 2003

A most important quantity in high-frequency analog transmission is the intermodulation distortion product. Experimental studies of the third order intermodulation distortion products in the modulation response of high-speed semiconductor lasers give very low values (<−60 dB) at low frequencies, an increase at a rate of 40 dB/dec as the modulation frequency is increased, and a leveling off at one-half of the relaxation oscillation resonance frequency. These experimental results can be well explained by a theory based on a perturbative analysis of laser dynamics.
Optical fiber hydrogen sensor
Authors: Butler M. A.
Published: February 2003

A new type of hydrogen sensor is reported in which an optical fiber is used as the sensing element. The fiber is coated with palladium which expands on exposure to hydrogen. This changes the effective optical path length of the fiber, which is detected by interferometric techniques. Preliminary experiments have demonstrated the effect and suggest a high sensitivity and a wide dynamic range for this kind of sensor. The experimental results are compared to calculated optical path length changes. Application of this kind of sensor to the detection of other chemicals appears feasible.
Nonresonant multiphoton ionization as a sensitive detector of surface concentrations and evaporation rates
Authors: Becker C. H. , Gillen K. T.
Published: February 2003

A general new mass spectrometric surface analysis method, using nonresonant multiphoton ionization of neutral material above the sample surface, has been applied to the examination of a copper NBS standard reference material. Sensitive trace element analysis has been demonstrated using an Ar+ ion beam to eject the surface material, showing sensitivities of <10−7 of a monolayer for all masses simultaneously. The technique is also shown to be useful for rapid and dynamic characterization of material composition, surface segregation, and differential evaporation (detecting partial pressures of ≲10−13 Torr). Many trace impurities are observed segregating to and evaporating from the surface of the NBS Cu sample when it is heated.
Ultrasensitive fingerprint detection of organometallic compounds by laser multiphoton ionization mass spectrometry
Authors: Stuke M.
Published: February 2003

Fast, sensitive, and selective fingerprint detection of organometallics, with emphasis on dimethyltelluride CH3TeCH3, is described, using short and ultrashort pulse tunable dye laser controlled time-of-flight mass spectroscopy. Excellent spatial (∼10 μm) and time (≪1 ns) resolutions combined with high single shot selectivity and sensitivity down to 10−7 Torr and below (corresponding to 3×109 cm−3 or about 3000 molecules in the observation region) plus mass identification are obtained.
Self-diffusivity of network oxygen in vitreous SiO2
Authors: Mikkelsen J. C.
Published: February 2003

Secondary ion mass spectrometry was used to profile the interdiffusion of network oxygen in a Si 16O2-Si 18O2 thin-film structure. The diffusivity from 1200 to 1400 °C can be described by D=2.6 cm2 s−1 exp (−4.7 eV/kT). The diffusivity values are lower, but with a higher activation energy, than those previously reported in the literature and approach the intrinsic diffusivity uncomplicated by extrinsic gas phase isotope exchange reactions.
Phase-locking characteristics of coupled ridge-waveguide InP/InGaAsP diode lasers
Authors: Kapon E. , Rav-Noy Z. , Lu L. T. , Yi M. , Margalit S. , Yariv A.
Published: February 2003

The phase-locking characteristics of two coupled, ridge waveguide InP/InGaAsP diode lasers emitting at 1.2 μm were investigated experimentally. The phase locking of the lasers was verified by the observation of phase-locked modes (supermodes) in the spectrally resolved near fields and distinct diffraction patterns in the far field. By independent control of the laser currents it was possible to vary continuously the mutual phase shift between the two phase-locked lasers and thus steer the far-field diffraction lobes. In addition, the separate current control could be utilized to obtain single longitudinal mode oscillation of the phase-locked lasers. Variation in one of the laser currents resulted then in tuning of the wavelength of this single mode over a range of 90 Å.
Atmospheric pressure operation of an electron beam excited KrF laser using Kr/F2 mixtures
Authors: Suda Akira , Obara Minoru , Fujioka Tomoo
Published: February 2003

Atmospheric pressure operation of a KrF laser pumped by 50-ns electron beams was experimentally investigated. For a 1-atm mixture of Kr and F2 without diluent, a specific output energy of 4.2 J/1 was obtained at 1.7-MW/cm3 excitation rate. Under this condition the intrinsic efficiency was about 5% (6% was maximum at 20% Kr in argon diluent) which was comparable to that from 1-atm normal (10% Kr) mixtures.
12-fs ultrashort optical pulse compression at a high repetition rate
Authors: Halbout J.-M. , Grischkowsky D.
Published: February 2003

We have produced 12-fs (full width at half-maximum), 0.5-MW optical pulses at a 500-Hz repetition rate by passing the amplified pulses from a colliding pulse, passively mode-locked ring dye laser through an optical fiber pulse compressor.
Nanometer scale electron beam lithography in inorganic materials
Authors: Salisbury I. G. , Timsit R. S. , Berger S. D. , Humphreys C. J.
Published: February 2003

Nanometer scale holes and lines have been produced directly in calcium fluoride, aluminium oxide, and magnesium oxide by an intense beam of electrons. There is a threshold beam current density for drilling, and the variation of this with voltage has been studied. Observations using electron energy loss spectroscopy have confirmed that metallic aluminium is produced during the drilling of aluminium oxide. Aluminium oxide may be drilled when in contact with the aluminium substrate, which remains undrilled.
Molecular beam epitaxial growth of high quality HgTe and Hg1−xCdxTe onto GaAs(001) substrates
Authors: Faurie J. P. , Sivananthan S. , Boukerche M. , Reno J.
Published: February 2003

HgTe and Hg1−xCdxTe epilayers have been grown for the first time onto GaAs (001) substrates by molecular beam epitaxy (MBE). A thin MBE CdTe buffer has been first deposited. The (001) orientation of the substrate is conserved during the growth. Despite the important lattice mismatch in situ electron diffraction experiments showed that the films have a high crystal quality. Hall measurements carried out on these layers confirm their high quality because they exhibited high electron Hall mobilities. We have shown also, using a Hall mobility profiling etching technique, that the interfacial disorder zone in a HgCdTe layer deposited on a 0.4-μm CdTe buffer layer could be less than 1 μm. This first report of very good electrical performances for Hg1−xCdxTe layers grown onto GaAs substrates is highly promising for growth and device applications regarding this material and related superlattices.
Initial transient phenomena in the plasma enhanced chemical vapor deposition process
Authors: Nguyen V. S. , Pan P. H.
Published: February 2003

A strong correlation between a silicon-rich interface in plasma deposited silicon nitride films with an initial transient phenomena during the plasma enhanced chemical vapor deposition process has been verified using optical emission techniques, plasma voltage potential (Vp) measurements, and Auger depth profile analysis. The data suggested that the silicon-rich interface may be an intrinsic property of all plasma deposited films examined. This observation was found to be independent of tool type. However, it is possible to reduce the silicon-rich interface thickness in plasma deposited films by shortening the transient time with judicious choice of tool and deposition conditions.
‘‘Thermal fixing’’ of Ti-indiffused LiNbO3 channel waveguides for reduced photorefractive susceptibility
Authors: Becker R. A.
Published: February 2003

A ‘‘thermal fixing’’ process that dramatically reduces the photorefractive susceptibility of Ti-indiffused LiNbO3 channel waveguides has been demonstrated. Guided-wave Mach–Zehnder interferometric modulators were used to characterize the photorefractive susceptibility of the waveguides. These devices were evaluated before and after the thermal fixing process which was seen to be erasable, reproducible, and long-lived. Photorefractive effects were reduced ten times for waveguide operation at λ=0.46 μm and more than 100 times for operation at λ=0.85 μm.
Influence of chemical driving forces in ion mixing of metallic bilayers
Authors: Cheng Y-T. , Van Rossum M. , Nicolet M-A. , Johnson W. L.
Published: February 2003

The effective interdiffusion coefficient of metallic bilayers under ion irradiation has been correlated with the heat of mixing of corresponding binary alloys. The results are interpreted according to Darken’s theory of chemically enhanced diffusion.
Monolithic integration of an InGaAsP/InP laser diode with heterojunction bipolar transistors
Authors: Shibata Jun , Nakao Ichiro , Sasai Yoichi , Kimura Soichi , Hase Nobuyasu , Serizawa Hiroyuki
Published: February 2003

A monolithic integration of an InGaAsP laser diode together with current supplying circuit on a single InP substrate has been achieved. Heterojunction bipolar transistors (HBT’s) have been constructed utilizing the burying epitaxial layers of the buried heterostructure laser diode. The laser has been successfully modulated up to 1.6 GHz through the HBT’s driving circuit with sinusoidal electrical signal.
Chirped arrays of diode lasers for supermode control
Authors: Kapon E. , Lindsey C. , Katz J. , Margalit S. , Yariv A.
Published: February 2003

We propose nonuniform structures of phase-locked diode lasers, which make it possible to discriminate efficiently against all the higher order array supermodes (lateral modes). In these nonuniform arrays, the effective mode index in each channel varies across the array. Consequently, the envelopes of the various supermodes, including the highest order one, differ significantly from each other. Thus, by proper tailoring of the gain distribution across the array, one can conveniently select the fundamental supermode. Such fundamental supermode oscillation is essential in order to obtain single lobe, diffraction limited beams and minimal spectral spread from phase-locked laser arrays.
Microwave-induced constant-voltage steps at one volt from a series array of Josephson junctions
Authors: Niemeyer J. , Hinken J. H. , Kautz R. L.
Published: February 2003

It is demonstrated that a series array of 1474 Josephson junctions can produce quantized voltages up to 1.2 V when driven by microwaves at 90 GHz in the absence of a dc bias. This result brings closer the possibility of a practical Josephson voltage standard at the 1-V level.
Diffusion of phosphorus during rapid thermal annealing of ion-implanted silicon
Authors: Oehrlein G. S. , Cohen S. A. , Sedgwick T. O.
Published: February 2003

The diffusion of ion-implanted phosphorus in silicon during rapid thermal annealing has been studied. Depending on the implant dose, we find two distinct kinds of diffusion behavior. For low dose (1×1014 cm−2) P+-implanted Si, a profile redistribution is observed which becomes observable at 900 °C for annealing times of 10 s, but which is temperature independent in the range 800–1150 °C. This initial redistribution is much more rapid than conventional diffusion coefficient data would predict. For high dose (2×1015 cm−2) P+ implanted and short time (10 s) annealed Si, the dopant profile broadening is strongly temperature dependent. The experimental profiles are in this case in agreement with concentration enhanced diffusion profiles.
Study of silicon contamination and near-surface damage caused by CF4/H2 reactive ion etching
Authors: Oehrlein G. S. , Tromp R. M. , Lee Y. H. , Petrillo E. J.
Published: February 2003

Silicon surfaces which had been exposed to a CF4 /H2 plasma have been characterized by x-ray photoelectron spectroscopy, ellipsometry, He ion channeling, and H profiling techniques. Plasma exposure leads to the deposition of a thin (∼30 Å thick) C,F-polymeric layer. Hydrogen and/or damage (displaced Si atoms) can be detected in the near-surface region up to a depth in excess of 400 Å from the Si surface.
Optical guided-wave gallium arsenide monolithic interferometer
Authors: Donnelly J. P. , DeMeo N. L. , Ferrante G. A. , Nichols K. B. , O’Donnell F. J.
Published: February 2003

A guided-wave interferometer capable of modulating 1.3-μm radiation via the electro-optic effect has been fabricated in GaAs. The interferometer uses three-guide couplers as the input and output sections and single-mode slab-coupled p+-n−-n+ rib waveguides fabricated by means of Be-ion implantation for the two active arms. An extinction of ≊14.5 dB of the output signal from the center guide is obtained with 22 V applied to one arm of the interferometer. Interferometers of this type should be capable of large signal modulation out to 5–10 GHz.
Generation of relativistic photoelectrons induced by excimer laser irradiation
Authors: Kawamura Y. , Toyoda K. , Kawai M.
Published: February 2003

For the first time, photoelectrons from a metal surface irradiated by a pulsed excimer laser were accelerated to relativistic energy. The energy, the current density, and the pulse duration of the accelerated photoelectrons were 0.41 MeV, 0.5 A/cm2, and 20 ns, respectively.
AgGaS2 infrared parametric oscillator
Authors: Fan Yuan Xuan , Eckardt R. C. , Byer R. L. , Route R. K. , Feigelson R. S.
Published: February 2003

We report the first operation of an optical parametric oscillator in a chalcopyrite crystal, AgGaS2. Tuning from 1.4 to 4.0 μm is demonstrated for 1.06-μm Nd:yttrium aluminum garnet pumping. The potential tuning range extends to the 12-μm transparency limit of the crystal.
Laser detection of diatomic products of plasma sputtering and etching
Authors: Walkup R. , Avouris Ph. , Dreyfus R. W. , Jasinski J. M. , Selwyn G. S.
Published: February 2003

We report on in situ detection of diatomic products of plasma sputtering and reactive ion etching using the technique of laser-induced fluorescence. The diatomic molecules SiN, SiO, and SiF are observed in the gas phase when a silicon surface is subjected to ion bombardment in plasmas containing N2, O2, and CF4, respectively. Information about the production mechanisms is obtained from the measured product concentrations under varying plasma conditions.
Recombination enhanced defect annealing in n-InP
Authors: Benton J. L. , Levinson M. , Macrander A. T. , Temkin H. , Kimerling L. C.
Published: February 2003

The first example of a recombination enhanced defect reaction in InP is reported. The major defect E(0.79 eV) introduced by 1-MeV electron irradiation of p+n junctions, formed by Zn-doped epilayers on undoped n-type substrates, is not observed with Schottky barrier structures on similar material. The defect exhibits a reduction in activation energy of recovery from 1.3 eV under pure thermal annealing to 0.42 eV with minority-carrier (hole) injection. The enhanced reaction rate is proportional to the square of the injected current showing that the process results from two particle capture.
Surface photovoltage in hydrogenated amorphous silicon
Authors: Kumar Shailendra , Agarwal S. C.
Published: February 2003

By solving Poisson’s equation in dark and light, it is concluded that the observed surface photovoltage in hydrogenated amorphous silicon necessarily involves a transfer of charge between the surface states and the space-charge region, and does not directly give the band bending. Experimental evidence which supports this conclusion is presented.
Effects of ion-implanted C on the microstructure and surface mechanical properties of Fe alloys implanted with Ti
Authors: Follstaedt D. M. , Knapp J. A. , Pope L. E. , Yost F. G. , Picraux S. T.
Published: February 2003

The microstructural and tribological effects of ion implanting C into Ti-implanted, Fe-based alloys are examined and compared to the influence of C introduced by vacuum carburization during Ti implantation alone. The amorphous surface alloy formed by Ti implantation of pure Fe increases in thickness when additional C is implanted at depths containing Ti but beyond the range of carburization. Pin-on-disc tests of 15-5 PH stainless steel show that implantation of both Ti and C reduces friction significantly under conditions where no reduction is obtained by Ti implantation alone; wear depths are also less when C is implanted. All available experimental results can be accounted for by consideration of the thickness and Ti concentration of the amorphous Fe-Ti-C alloy. The thicker amorphous layer on samples implanted with additional C extends tribological benefits to more severe wear regimes.
Integrated-optical frequency translator with stripe waveguide
Authors: Heismann F. , Ulrich R.
Published: February 2003

We demonstrate electro-optic frequency shifting of laser light (λ=723 nm), electronically tunable through more than ± 1 MHz, in a LiNbO3: Ti single-mode stripe waveguide, using polarization conversion at a traveling index grating, driven by two phase-quadrature voltages of ∼27 V at the offset frequency. The optical carrier and undesired sidebands are suppressed better than 30 dB by polarizers, conversion efficiency ≥70%, device length 4.5 mm, optical bandwidth ∼1 nm; direct butt coupling to fibers is possible.
Subpicosecond electro-optic sampling using coplanar strip transmission lines
Authors: Mourou G. A. , Meyer K. E.
Published: February 2003

Electrical sampling with a temporal resolution of less than 500 fs has been achieved using coplanar transmission lines on electro-optic substrates. The improved performance over the previously demonstrated balanced stripline is due to the reduced dimensions, i.e., distance between the electrodes and width of the electrodes, achievable with photolithographic technique. By further reducing the line dimensions to 10–20-μm range, this technique makes the temporal resolution of electrical waveforms in the range of 100 fs possible.
Plasma-enhanced chemical vapor deposition of β-tungsten, a metastable phase
Authors: Tang C. C. , Hess D. W.
Published: February 2003

Plasma-enhanced chemical vapor deposition of a metastable phase of tungsten ( β-W) is performed using tungsten hexafluoride and hydrogen as source gases. At 350 °C, the as-deposited resistivity of these films is ∼50 μΩ cm. After heat treatments between 650 and 750 °C in forming gas, the resistivity drops below 11 μΩ cm. Concomitant with this resistivity change is a phase change to α-W, the equilibrium, body-centered-cubic form.
Growth of Cd1−xMnxTe films with 0<x<0.9 by atomic layer epitaxy
Authors: Pessa M. , Jylhä O.
Published: February 2003

Thin Cd1−xMnxTe semiconductor films with x ranging from 0 to 0.9 have been grown on CdTe (111) substrates using the atomic layer epitaxy method. The films grow epitaxially at all concentrations and show no manganese interdiffusion. The films are characterized by low-energy electron diffraction, Auger electron spectroscopy and angle-resolved UV photoemission.
Spatially modulated photoconductivity at N-AlGaAs/GaAs heterojunctions and formation of persistent charge patterns with submicron dimensions
Authors: Tsubaki K. , Sakaki H. , Yoshino J. , Sekiguchi Y.
Published: February 2003

The electron concentration at an N-AlGaAs/GaAs interface is shown to be spatially modulated at low temperatures by the selective photoionization of deep donors in AlGaAs using two interfering laser beams. The charge pattern thus formed is persistent and detected by measuring the anisotropy of the channel conductivity. Grating patterns with a period as small as 0.6 μm were successfully recorded in accordance with the prediction that spatial resolution comparable with the AlGaAs layer thickness (∼0.1 μm) will be achieved.
Electronic properties versus composition of thin films of CuInSe2
Authors: Noufi R. , Axton R. , Herrington C. , Deb S. K.
Published: February 2003

The electrical properties of thin-film CuInSe2 (<4 μm thick) deposited by coevaporation of the elements have been measured by different techniques as a function of material composition. A correlation between the Cu/In and Se/metal ratios versus majority-carrier concentration is established. A qualitative scheme is developed, based on experiments, which predicts the majority-carrier type and concentration in relation to the stoichiometry of the material.
Beam energy effects in electron beam lithography: The range and intensity of backscattered exposure
Authors: Jackel L. D. , Howard R. E. , Mankiewich P. M. , Craighead H. G. , Epworth R. W.
Published: February 2003

The range and intensity of backscattered exposure from a silicon substrate were measured as a function of incident electron energy. The range is proportional to the energy to the 1.7 power. The integrated energy deposited at the silicon surface by backscattered electrons is about 0.8 of the energy deposited by the incident electrons and is nearly independent of the incident beam electron energy. These results show that the severity of the proximity effect, the exposure of regions not addressed by the beam, can be reduced by using high beam energy since the backscattered electrons are spread over a distance much larger than minimum feature sizes.
Raman scattering study of the properties and removal of excess Te on CdTe surfaces
Authors: Amirtharaj P. M. , Pollak Fred H.
Published: February 2003

We have studied Raman scattering from CdTe 〈100〉, 〈110〉, and 〈111〉 surfaces subjected to various surface treatments. Our investigation shows that 0.1% Br/methanol etch or chemomechanical polish leaves a thin residual layer of polycrystalline Te of thickness 10–40 Å (under a tensile stress of about 8 kbar) and that this Te film can be removed by a rinse in a 1 N KOH in methanol solution.
Temperature dependence of the magnetostriction constant of nearly zero magnetostriction amorphous alloys
Authors: Hernando A. , Madurga V. , Núñez de Villavicencio C. , Vázquez M.
Published: February 2003

In the present work, the temperature dependence of the magnetostriction constant, λs, is presented for two Co-rich amorphous alloys which have a very low magnetostriction (about 10−7). These measurements have been carried out with the help of a new sensitive method and a change of sign of λs has been found experimentally at temperatures below the Curie point. We have interpreted it by taking into account the different temperature dependence of single-ion and two-ion constributions to λs. Furthermore, after magnetic annealing, a proportionality exists between λs and the magnetic induced anisotropy when they are measured at room temperature. These results are interpreted in connection with the temperature dependence of λs.
Thermal oxidation of 3C silicon carbide single-crystal layers on silicon
Authors: Fung C. D. , Kopanski J. J.
Published: February 2003

Thermal oxidation of thick single-crystal 3C SiC layers on silicon substrates was studied. The oxidations were conducted in a wet O2 atmosphere at temperatures from 1000 to 1250 °C for times from 0.1 to 50 h. Ellipsometry was used to determine the thickness and index of refraction of the oxide films. Auger analysis showed them to be homogeneous with near stoichiometric composition. The oxide growth followed a linear parabolic relationship with time. Activation energy of the parabolic rate constant was found to be 50 kcal/mole, while the linear rate constant was 74 kcal/mole. The latter value corresponds approximately to the energy required to break a Si–C bond. Electrical measurements show an effective density of 4–6×1011 cm−2 for fixed oxide charges at the oxide-carbide interface, and the dielectric strength of the oxide film is approximately 6×106 V/cm.
Photochemical dry etching of GaAs
Authors: Ashby C. I. H.
Published: February 2003

GaAs exhibits greatly enhanced reactivity with gas-phase reactive Cl species when the surface is irradiated with low intensity laser light having a frequency which can excite above the band gap of GaAs. This laser-induced reactivity is shown to be photochemical rather than thermal in origin. This is the first reported observation of a purely photochemical dry etching process for a III-V semiconductor material.
Fabrication of metal-epitaxial insulator-semiconductor field-effect transistors using molecular beam epitaxy of CaF2 on Si
Authors: Smith T. P. , Phillips Julia M. , Augustyniak W. M. , Stiles P. J.
Published: February 2003

Fabrication of metal-epitaxial insulator-semiconductor field-effect transistors by molecular beam epitaxial growth of CaF2 on Si is reported for the first time. These devices have a room-temperature electron mobility of 300 cm2/Vs and a threshold voltage of 0.5 V. The breakdown voltage of the films ranges from ≳105 to ≳106 V/cm in different regions of the film. These devices will be important for the characterization and improvement of the interface transport properties of the CaF2/Si system.
Solid phase epitaxy of polycrystalline silicon films: Effects of ion implantation damage
Authors: Quach N. T. , Reif R.
Published: February 2003

Thin polycrystalline silicon films (2100 Å) were deposited on chemically cleaned silicon substrates by low-pressure chemical vapor deposition. The polysilicon films were then amorphized by 28Si ion implantation at reduced temperatures with damage densities ranging from 1.25×1024 to 1×1025 eV/cm3. Isochronal annealing of the films was performed at 550–1000 °C in a flowing N2 ambient. It was found that the minimum temperature at which the films recrystallized epitaxially is inversely proportional to the implantation damage density. For an amorphized film recrystallized at 550 °C on an antimony heavily doped silicon substrate, secondary ion mass spectroscopy data show that solid-state out-diffusion and autodoping effects are negligible.
Frequency stabilization of 1.5-μm InGaAsP distributed feedback laser to NH3 absorption lines
Authors: Yanagawa T. , Saito S. , Yamamoto Y.
Published: February 2003

NH3 absorption lines due to vibration-rotation transitions are observed at 1.50–1.54 μm by using an InGaAsP superluminescent diode. A 1.5-μm InGaAsP distributed feedback (DFB) laser is frequency stabilized to an NH3 linear absorption line at 15196 Å. Frequency stability of σ(2,τ)=8×10−11τ−1 is achieved for an averaging time range of 10 ms≤τ≤1 s. Such an absolute frequency-stabilized DFB laser is useful for coherent optical system applications, since it is free from the longitudinal mode jumping which results from a wide range of temperature changes and long-term device degradation.
Quantum noise and dynamics in quantum well and quantum wire lasers
Authors: Arakawa Yasuhiko , Vahala Kerry , Yariv Amnon
Published: February 2003

We calculate the relaxation oscillation corner frequency fr and the linewidth enhancement factor α for both a quantum well and a quantum wire semiconductor laser. A comparison of the results to those of a conventional double heterostructure device indicates that fr can be enhanced by 2× in the quantum well case and 3× in the quantum wire case while α is reduced in both cases.
Photoacoustic measurement of thermal properties of a thin polyester film
Authors: Lachaine André , Poulet Patrick
Published: February 2003

The phase and the amplitude of the photoacoustic signal are measured as a function of chopping frequency for a thin polyester film, using two different backing materials (water and ethanol). Analysis of the results shows agreement with Rosencwaig–Gersho theory [J. Appl. Phys. 47, 64 (1976)] and provides values of the thermal diffusivity and the thermal effusivity of the sample.
Directional laser recrystallization of eutectic Si-CoSi2 thin films
Authors: Ditchek B. M. , Emma T.
Published: February 2003

A method for the preparation of lamellae of Si and CoSi2 using thin-film eutectic solidification techniques is presented. In the experiment, a laser was used to melt and directionally solidify an alloyed film of Co and polycrystalline Si on a thermally oxidized Si wafer. Using traverse rates as rapid as 8 cm/s, 50-nm-wide CoSi2 stripes, separated by comparable amounts of Si are obtained. An analysis of the chemistry and microstructure of the film before and after laser scanning is discussed.
New long-wavelength photodetector based on reverse-biased doping superlattices
Authors: Horikoshi Y. , Fischer A. , Ploog K.
Published: February 2003

A new GaAs photodetector of low capacitance and with high sensitivity in the whole 0.8–1.4-μm wavelength range has been fabricated from GaAs doping superlattices grown by molecular beam epitaxy. The highly doped yet semi-insulating superlattice allows application of high reverse bias via selective n+ and p+ electrodes also at room temperature. The excellent photoresponse of the totally depleted device at energies far below the GaAs energy gap arises from the existence of pronounced tail states in the forbidden gap region of the superlattice. Under operating conditions the capacitance of the detector depends only on the electrode geometry and can thus be kept extremely low. This implies high-speed response of the device.
Low loss Ge-Se chalcogenide glass optical fibers
Authors: Katsuyama T. , Ishida K. , Satoh S. , Matsumura H.
Published: February 2003

Infrared optical fibers composed of Ge-Se based chalcogenide glass have been fabricated by using a specially designed drawing apparatus. Transmission loss of less than 1 dB/m was observed in the IR region of 2–10 μm except at 4.5 μm. The minimum loss is 0.2 dB/m at 5.5-μm wavelength.
In Plants, 3-O-Methylglucose Is Phosphorylated by Hexokinase But Not Perceived as a Sugar
Authors: Cortès Sandra , Gromova Marina , Evrard Adeline , Roby Claude , Heyraud Alain , Rolin Dominique B. , Raymond Philippe , Brouquisse Renaud M.
Published: February 2003

In plants, sugars are the main respiratory substrates and important signaling molecules in the regulation of carbon metabolism. Sugar signaling studies suggested that sugar sensing involves several key components, among them hexokinase (HXK). Although the sensing mechanism of HXK is unknown, several experiments support the hypothesis that hexose phosphorylation is a determining factor. Glucose (Glc) analogs transported into cells but not phosphorylated are frequently used to test this hypothesis, among them 3-O-methyl-Glc (3-OMG). The aim of the present work was to investigate the effects and fate of 3-OMG in heterotrophic plant cells. Measurements of respiration rates, protein and metabolite contents, and protease activities and amounts showed that 3-OMG is not a respiratory substrate and does not contribute to biosynthesis. Proteolysis and lipolysis are induced in 3-OMG-fed maize (Zea mays L. cv DEA) roots in the same way as in sugar-starved organs. However, contrary to the generally accepted idea, phosphorous and carbon nuclear magnetic resonance experiments and enzymatic assays prove that 3-OMG is phosphorylated to 3-OMG-6-phosphate, which accumulates in the cells. Insofar as plant HXK is involved in sugar sensing, these findings are discussed on the basis of the kinetic properties because the catalytic efficiency of HXK isolated from maize root tips is five orders of magnitude lower for 3-OMG than for Glc and Man.