bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation between pulse shape and gain of a CO2 TEA laser
Authors: Neve de Mevergnies M.
Published: February 2003

The laser pulse width and delay has been measured for a number of selected P- and R-branch lines of the [00 °1-10 °0] and [00 °1-02 °0] transitions. It is concluded that the pulse width varies exponentially, and the pulse delay linearly, with the inverse of the gain of the selected laser line.
Air breakdown by pulsed-laser radiation in the 2.7- and 3.8-μm region
Authors: Soileau M. J.
Published: February 2003

The breakdown thresholds of unfiltered laboratory air were measured in the 3.8- and 2.7-μm regions. The breakdown threshold at 10.6 μm was also measured under identical experimental conditions in order to provide a correlation with previous work. Measurements at different focal-spot radii were used to establish an empirical scaling law for the focal-spot radius dependence of the breakdown thresholds. This scaling law was then used to reduce all the data to a common focal-spot radius. The results indicate that the air breakdown threshold has a λ−2 dependence in the 2.7–10.6-μm range.
Magnetostatic surface wave propagation on a periodic YIG film layer
Authors: Chang N. S. , Matsuo Y.
Published: February 2003

The filter characteristics of a magnetostatic surface wave propagating in a layered YIG film corrugated on one layer and noncorrugated on the other are described. The effect of the saturation magnetization of a noncorrugated layer on the filter is analytically evaluated by solving the exact dispersion relation. Also, the magnetic loss effect on the filter is considered. It is found that the Q value of the filter in our new model is generally twice as large as that of contemporary periodic YIG film filters.
Extension of a theorem used in the investigation of p-n junctions with the scanning electron microscope to arbitrary geometries and arbitrarily inhomogeneous material
Authors: von Roos Oldwig
Published: February 2003

It is shown that the relationship limn→S ∂Isc/ ∂n= (s/D) Isc connecting the normal derivative of the short circuit Isc generated by an electron or ion beam in a P-N junction with the surface recombination velocity s and the diffusion constant D is valid for arbitrary junction geometries, arbitrary doping profiles, and arbitrary distributions of recombination centers, provided that (1) low-level injection prevails and (2) the radius of the beam-semiconductor interaction volume is small compared to the local diffusion length. It thus becomes possible to study the surface recombination velocity of the front surface of a highly nonuniformly doped shallow junction representative of, for instance, a solar cell by means of an ion beam.
A SAW/CCD programmable matched filter
Authors: Ralston R. W. , Smythe D. L. , Stern E.
Published: February 2003

A charge-coupled device (CCD) has been integrated with a surface-acoustic-wave (SAW) piezoelectric delay line in a hybrid gap-coupled structure to produce an electronically programmable analog matched filter in which the filter function is controlled by the charge pattern clocked into the CCD. This device allows analog-analog correlation of SAW input signals of ≲40-MHz bandwidth and ≲3.5-μs duration. Programming time is 6 ms at a 100-kHz clock rate, and the reference holding time is 1 s for a 3-dB degradation of the correlation peak. Operation as a matched filter for a 3.25-μs-long 13-bit Barker-encoded signal yields a peak correlation level of −41 dB m.
Magnetic field control of reactive plasma etching
Authors: Minkiewicz V. J. , Chen M. , Coburn J. W. , Chapma B. N. , Lee F K.
Published: February 2003

The application of a magnetic field to control the spatial distribution of chemical species in reactive plasma etching produces a situation in which either etching or deposition can occur. In a low-voltage hot-filament triode configuration in which the plasma is confined by an externally applied magnetic field, Si samples are subjected to a CF4 plasma. Etching or deposition of a cross-linked fluorocarbon polymer can occur, depending on the position of the sample with respect to the core of the discharge. These results are generally applicable to all reactive plasma-etching reactors.
Laser-induced metal-to-semiconductor phase transition in mixed Al-Sb films
Authors: Andrew R. , Ledezma M. , Lovato M. , Wautelet M. , Laude L. D.
Published: February 2003

Metallic films consisting of overlapping polycrystalline layers of, alternatively, Al or Sb atoms in overall equal proportions are irradiated at 300 °K with 80-mJ/cm2 microsecond dye laser pulses of 2-eV photon energy. Using transmission electron microscopy, electron diffraction, optical transmission, and conductivity measurements, the presence of semiconducting AlSb is fully identified in systematically all the irradiated films after one single pulse, giving unambiguous evidence for a phase transition between the layered fcc-rhomboedric metallic structure and the blende structure of AlSb.
Analysis on the steady-state amplification of ArF and KrF discharge lasers
Authors: Watanabe Shuntaro , Obara Akira , Sato Takuzo , Kashiwagi Hiroshi , Endoh Akira
Published: February 2003

The saturation behavior of the steady-state amplification of discharge-pumped ArF and KrF lasers have been analyzed by numerical calculation taking into account absorption, spontaneous decay, and pumping. This analysis predicts the noticeable pulse-width broadening due to amplification in good agreement with experiments. The small-signal-gain g0 and absorption coefficients a were determined simultaneously by the best fits of experimental saturation curves to numerically calculated ones with the results of g0=3.5%/cm and a=0.2%/cm for the ArF laser and g0=5.0%/cm and a=0.4%/cm for the KrF laser under the investigated conditions.
Suppression of side lobes in the far field of AlGaAs DH stripe lasers by a Te facet coating
Authors: Kerps Dieter
Published: February 2003

Side lobes observed in the far-field distribution parallel to the junction plane of DH AlGaAs stripe-geometry lasers can be suppressed by a self-aligned facet masking process. A hole, burnt into a Te coating by the laser emission, allows only the main lobe emission to pass. The result supports the attribution of side lobes to refraction tails in the near field typical of a negative refractive index step wave guide as discussed in a previous paper [see R. W. Engelmann, D. Kerps, and F. Nunes, IEEE Quantum Electron. (to be published)].
Variable-temperature photoacoustic effect: Application to phase transition
Authors: Pichon C. , Le Liboux M. , Fournier D. , Boccara A. C.
Published: February 2003

A low-temperature-adapted photoacoustic cell using an electret microphone and a MOSFET preamplifier is described. This cell can operate between 5 and 300 K in a gas-flow cryostat. By way of illustration, it is used here to perform a new kind of photoacoustic measurement, i.e., to study the specific-heat anomaly of various insulators in the neighborhood of magnetic phase transitions.
The liquid-crystal alignment properties of photolithographic gratings
Authors: Cheng J. , Boyd G. D.
Published: February 2003

The liquid-crystal alignment properties of gratings with a 1–10-μm period are described. Experiments are presented to compare the roles of interfacial interactions and surface topography in determining alignment. It is shown that grooves are neither necessary nor always sufficient to produce alignment. Interfacial forces can give rise to strongly pinned alignment, governed by various biases applied during the first appearance of long-range order at the interface.
Flexible GaAs ribbons
Authors: Tantraporn W.
Published: February 2003

Thin GaAs ribbons from Ga-AsCl3-H2 epitaxy are flexible. The rapid growth occurs along a 〈112̄〉 vector. The thin edges are {110}-type planes while the flat surfaces appear to be {111}A. A ribbon of dimensions 2×0.1×0.002 cm3 can be bent to 1 cm diameter without breakage.
Second-harmonic generation with Ga1−xAlxAs lasers and KNbO3 crystals
Authors: Günter P. , Asbeck P. M. , Kurtz S. K.
Published: February 2003

Efficient second-harmonic generation from pulsed Ga1−xAlxAs injection lasers operating at room temperature has been observed in KNbO3 crystals. The Al concentration x of the laser was chosen such that the output corresponds to the room-temperature noncritical 90° phase-matching wavelength λpm=860 nm for the nonlinear optical coefficient d32 of KNbO3. Up to 0.35-mW peak harmonic power was obtained with a pulsed fundamental peak power of 785 mW incident on a 5.74-mm-long crystal.
Zn-diffused In0.53Ga0.47As/InP avalanche photodetector
Authors: Matsushima Yuichi , Sakai Kazuo , Akiba Shigeyuki , Yamamoto Takaya
Published: February 2003

Mesa In0.53Ga0.47As avalanche photodetectors were successfully fabricated by liquid-phase-epitaxial growth on (100) -InP substrate and Zn-diffusion technique. An avalanche multiplication M as high as 32 was measured under broad-area illumination provided by a cw InGaAsP laser at 1.3 μm. Distribution of M was measured by an electron-beam-induced current image of a scanning electron microscope, and uniform multiplication profiles were observed up to M=3 and M=12 at the mesa diameter of 300 and 150 μm, respectively.
A monolithic series-connected Al0.93Ga0.07As/GaAs solar cell array
Authors: Borden Peter G.
Published: February 2003

A monolithic Al0.93Ga0.07As/GaAs solar cell array has been demonstrated. It consists of four adjacent 0.1×0.55-cm cells connected in electrical series with an etched groove isolation and metal interconnect scheme. With 819.5 W/m2 incident solar radiation, it exhibits an open-circuit voltage of 3.96 V, short-circuit current of 1.01 mA, and a fill factor of 0.625. The observed efficiency of 13.85% appears to be limited by the mechanisms of contact resistance and interconnect area.
Antireflection properties of indium tin oxide (ITO) on silicon for photovoltaic applications
Authors: Cheek G. , Genis A. , DuBow J. B. , Verneker V. R. Pai
Published: February 2003

The short-circuit current density (Jsc) of indium tin oxide (ITO/silicon solar cells has been shown both theoretically and experimentally to be a function of the thickness of the ion beam sputtered ITO layer. These results can be accounted for by computing the optical reflection from the ITO/silicon interface.
Beat frequency generation between visible lasers with frequency differences in the 80-GHz band
Authors: Burghardt B. , Hoeffgen H. , Meisel G. , Reinert W. , Vowinkel B.
Published: February 2003

Millimeter-wave GaAs Schottky barrier diodes were used as fast light detectors. It was possible to observe beat signals between a HeNe laser oscillating at 633 nm and a cw dye laser with approximately 80-GHz frequency offset. Thus, great frequency differences between lasers emitting in the visible can be determined with the high accuracy inherent in heterodyning techniques.
The quantum yield of silicon in the visible
Authors: Geist Jon , Zalewski Edward F.
Published: February 2003

Extremely high accuracy measurements of the internal quantum efficiency of shallow-junction silicon photodetectors were fit with various theoretical models. The internal quantum efficiency was found to be rather model independent indicating its possible use as a radiometric standard. The results of this investigation indicate that the quantum yield of silicon is unity to within a few tenths of one percent in the visible.
High avalanche gain in small-area InP photodiodes
Authors: Lee T. P. , Burrus C. A. , Dentai A. G. , Ballman A. A. , Bonner W. A.
Published: February 2003

Extremely high avalanche gains, up to 2×104, accompanied by low leakage current and moderate excess avalanche noise, have been observed in small areas of diffused p-n junctions in undoped n-type InP. The results imply that dislocation densities much less than 104 cm−2 probably will be a prerequisite for practical long-wavelength avalanche photodiodes in the InGaAsP/InP system.
An additional source of photovoltage in photoconductive materials
Authors: Fonash S. J. , Ashok S.
Published: February 2003

A possible additional source of photovoltage in solar cells made on photoconductive materials is identified. Arising from suitable compositional or doping variations of the material, this excess voltage could significantly enhance the open-circuit voltage of solar cells fabricated on amorphous Si : H, related alloys, and other materials that exhibit pronounced photoconductivity.
Pulsed electron-beam annealing of selenium-implanted gallium arsenide
Authors: Inada T. , Tokunaga K. , Taka S.
Published: February 2003

Electrical properties of selenium-implanted gallium arsenide annealed by a single shot of high-power pulsed electron beams have been investigated by differential Hall-effect and sheet-resistivity measurements. It has been shown that higher electrical activation of implanted selenium can be obtained after electron-beam annealing at an incident energy density of 1.2 J/cm2, independent of heating of GaAs substrate during implantation. Measured carrier concentrations exhibit uniformly distributed profiles having carrier concentrations of 2–3×1019/cm3, which is difficult to realize by conventional thermal annealing.
Photoluminescence of gallium arsenide encapsulated with aluminum nitride and silicon nitride
Authors: Birey Hulya , Pak Sung-Jae , Sites J. R.
Published: February 2003

Aluminum nitride and silicon nitride films were deposited on lightly doped n-type GaAs : Si by low-energy ion beam sputtering. Mechanically, the films were stable at annealing temperatures above 900 °C. In contrast to bare GaAs and previously reported encapsulation with Si3N4, where the 1.36-eV line appears at relatively low annealing temperatures, there was no change in the photoluminescence spectrum until the samples were annealed at 800 °C in the case of aluminum nitride and 900 °C for silicon nitride.
Tunable submillimeter sources applied to the excited state rotational spectroscopy and kinetics of CH3F
Authors: Blumberg W. A. M. , Fetterman H. R. , Peck D. D. , Goldsmith P. F.
Published: February 2003

Tunable submillimeter radiation, generated and detected using optically pumped lasers and Schottky diode mixers, has been used in an infrared-submillimeter double resonance investigation of CH3F. This technique permits the direct observation of the molecular rotational spectra and kinetics of excited vibrational states and is particularly important for those molecules which are candidates for optically pumped submillimeter lasers.
Thin films of LiNbO3, doped with Na+ and Co2++Zr4+, grown by liquid-phase epitaxy
Authors: Neurgaonkar R.R. , Kalisher M.H. , Staples E. J. , Lim T. C.
Published: February 2003

LiNbO3 thin films doped with Na+ and Co2++ Zr4+ have been obtained by the liquid-phase epitaxial (LPE) technique from Li2O-V2O5 flux. X-ray diffraction studies indicated that the films had a high single crystallinity with good epitaxy. The Na+ and Co2+ +Zr4+ doped LiNbO3 films showed a reduction in the temperature coefficient of surface acoustic wave velocity.
Isolation of type-2 magnetic contrast in the SEM by a lock-in technique
Authors: Wells Oliver C.
Published: February 2003

The backscattered electron (BSE) signal in the scanning electron microscope (SEM) can be modulated, under the proper experimental conditions, by magnetic fields inside the specimen. This modulation is typically less than 1% of the collected current, and this must be amplified so as to be clearly visible in the recorded image. We have found that unwanted topographic contrasts can be reduced in comparison with this magnetic contrast by a lock-in technique. With a 1-μm permalloy film as the sample, the domain walls can be moved repetitively by applying a sinusoidal magnetic field. If the video waveform is processed using a lock-in amplifier controlled by this same signal, then the portions of the domain walls that move are emphasized in the image. Parts of the image which are not affected by the modulating magnetic field are strongly attenuated in the processed image.
A new thin-film electroluminescent material—ZnF2 : Mn
Authors: Morton D. C. , Williams F. E.
Published: February 2003

Both ac and dc orange (580 nm) electroluminescence (EL) are reported for thin films of ZnF2 : Mn sandwiched between SiO semi-insulating films. All layers are formed by vacuum evaporation and no postdeposition annealing is required. Unique power input and efficiency-vs-frequency characteristics are observed, in part due to the 0.1-s lifetime of excited Mn in ZnF2; hysteresis in the brightness-voltage characteristic occurs. The brightness and power efficiency are found to be, respectively, 10 f L and 0.5% under suitable operating conditions.
Laser enhanced electroplating and maskless pattern generation
Authors: von Gutfeld R. J. , Tynan E. E. , Melcher R. L. , Blum S. E.
Published: February 2003

Maskless plating has been achieved through a new technique that utilizes a cw or pulsed laser, focused onto an electrode in an electroplating bath. In the region of optical absorption on the cathode, plating enhancement rates on the order of 103 occur for optical power densities on the order of 104 W/cm2. Laser scanning produces a plating pattern along the scanning path. A qualitative theory based on convective mass transport is used to explain the results.
Detection of ferromagnetic resonance by photoacoustic effect
Authors: Nunes O. A. Cleves , Monteiro A.M.M. , Neto K. Skeff
Published: February 2003

By exploring the simple periodic heat-flux principle of the photoacoustic cell we propose and demonstrate experimentally the usefulness of the photoacoustic cell for studying the ferromagnetic resonance. An interesting feature of this technique is that it offers special advantages over conventional spectroscopic methods used in ferromagnetic resonance because of the simplicity of measurements. An application is made for the case of an iron thin foil.
Coherent optical image amplification by an injection-locked dye amplifier at 632.8 nm
Authors: Akins Robert , Lee Sing
Published: February 2003

Coherent amplification of images illuminated by the 632.8-nm radiation of He-Ne has been successfully demonstrated using a two-stage injection-locked pulsed dye amplifier technique. A gain of three times has been measured using Cresyl Violet 620 and Rhodamine B in ethanol, while maintaining signal bandwidth, relative phase, and direction, over a one-quarter μs pulse duration. A space bandwidth product of 500 000 was obtained by incorporation of the image amplifier into an optical image processing system.
Improved temperature stability in SAW resonator filters using multiple coupling paths
Authors: Coldren L. A.
Published: February 2003

An extension of the interfering delay path concept, put forth by Browning and Lewis, is used to provide temperature compensation within a class of two-section SAW resonator filters without adding significantly to to filter complexity. An example calculation shows that the temperature range ΔT for ±1° phase stability can be increased by threefold over the ΔT range provided by conventional filters on ST-X quartz. Design equations are given.
Observation of stimulated Brillouin backscatter saturation in an underdense plasma for long CO2 laser pulses
Authors: Pietrzyk Z. A. , Carlstrom T. N.
Published: February 2003

Experimental evidence of low saturation levels of stimulated Brillouin backscatter from a magnetically confined, underdense, CO2 laser heated plasma is reported. Simple arguments are given to suggest an explanation for the saturation levels observed. A comparison with other experiments suggests that the focusing system of the incident laser beam may influence the saturation level of the backscattered radiation.
Polycrystalline silicon by glow discharge technique
Authors: Morin F. , Morel M.
Published: February 2003

Polycrystalline silicon was obtained by glow discharge decomposition of silane on heated amorphous substrates. The influence of substrate temperature on crystalline structure and electrical conductivity of silicon films was investigated. Textured polycrystalline films were obtained above 450 °C.
Isoelectronic traps in GaAs0.6P0.4 by nitrogen implantation and CO2-laser annealing
Authors: Takai M. , Ryssel H.
Published: February 2003

A continuous CO2 laser was used for the first time to anneal the damage in GaAs0.6P0.4 induced during nitrogen implantation and to create nitrogen isoelectronic traps. Laser-annealed samples showed isoelectronic signals which are by a factor of 6–7 stronger as compared with thermally annealed samples. The intensity of the nitrogen-induced emission from the laser-annealed samples was up to 50% higher than that of the near-band-gap emission from the starting material.
Removal of radiation-induced electron traps in MOS structures by rf annealing
Authors: Ma T. P. , Chin M. R.
Published: February 2003

rf annealing technique has been successfully applied to remove the radiation-induced electron traps in MOS structures. The experimental details, including the annealing apparatus, sample fabrication and irradiation, sample measurements, and data analysis will be described. Some suggestions concerning the possible mechanisms involved in the annealing of neutral traps, in particular, the recombination-enhanced defect reactions, will be presented.
Measurement of the size dependence of the current-phase relation in microbridge Josephson junctions
Authors: Pei S. S. , Lukens J. E. , Sandell R. D.
Published: February 2003

We present the first direct measurements of the size effect on the current-phase relation of microbridge Josephson junctions. The phase difference across the bridge is obtained by subtracting the phase shift of the thin-film leads from the total phase shift. We have found that the current-phase relations are sinusoidal for both uniform and variable thickness bridges with dimensions much smaller than ξ (T). For narrow uniform thickness bridges with width ≪ξ (T), the measured length dependence of the current-phase relation is in good agreement with the calculation of Likharev and Yakobson for variable thicknes bridges.
A milliwatt-level cw laser source at 224 nm
Authors: Jain Kanti
Published: February 2003

Several new results are reported in singly ionized, hollow-cathode silver, copper, and gold vapor lasers. For the first time, a milliwatt-level cw laser source is demonstrated at 224 nm, with a threshold as low as 2 A. We have also extracted several hundred milliwatts of peak pulse power output at a number of wavelengths below 300 nm.
Vacuum ultraviolet picosecond pulse generation using cw mode-locked dye lasers
Authors: Economou N. P. , Freeman R. R. , Heritage J. P. , Liao P. F.
Published: February 2003

We report the generation of a continuous train of pulses of ∼5-psec duration with wavelength tunable near 1700 Å using two synchronously mode-locked cw dye lasers. Two-photon resonantly enhanced 4-wave mixing in Sr vapor was employed to obtain approximately 10−10 W average power (∼10−7 W/pulse) for inputs of less than 5 mW. The efficiency of this process was measured and is quantitatively compared to previous vacuum ultraviolet coherent radiation generation schemes in Sr vapor.
cw optically resonance-pumped HF laser
Authors: Wang J. H. S. , Finzi J. , Baily P. K. , Holleman G. W. , Hui K. K. , Mastrup F. N.
Published: February 2003

cw HF laser oscillation has been demonstrated in an HF/He mixture excited by optical resonance pumping with a multiline chemical HF laser. Laser oscillation was observed over a pressure range from 25 to 110 Torr. The maximum outcoupled power was 20.2 W with 5.3% overall efficiency.
z-dependent absorption and stimulated backscatter processes in laser produced plasmas
Authors: Jackel S. , Loebenstein H. M. , Zigler A. , Zmora H. , Zweigenbaum S.
Published: February 2003

Low- and high-atomic-number targets were irradiated at normal and oblique incidences with high focused intensity, 2.5-nsec duration of 1.06-μm laser pulses. Calorimetry and spectroscopy of ω and 2ω light reflected back into the focusing lens was performed. Results show a dramatic reduction in the specularly reflected light from high-atomic-number targets. Brillouin backscatter was observed throughout the range 1014–1016 W/cm2. 2ω spectra indicated the presence of an electron-ion decay instability with a threshold at 2×1015 W/cm2.
Primary defects in low-fluence ion-implanted silicon
Authors: Wang K. L.
Published: February 2003

Electrical defect energy levels created by low-fluence ionic impact were investigated using transient capacitance spectroscopy. The ion species used are 1H+, 2H+2, 4He+, 11B+, and 31P+. The defect levels were identified by comparing these levels with those obtained in electron-irradiated structures. The defect production yields for various ion species and for different fluences were obtained. Only a small fraction of the carrier removal could be accounted for by the observed DLTS levels.
Evidence for void interconnection in evaporated amorphous silicon from epitaxial crystallization measurements
Authors: Bean J. C. , Poate J. M.
Published: February 2003

The epitaxial crystallization rate of UHV-deposited amorphous silicon is shown to be 1–2 orders of magnitude lower than the rate reported for ion implanted amorphous layers. The rate of growth is a function of depth, decreasing towards the layer surface. Crystallization is inhibited in samples exposed to air at room temperature. Results indicate that gases migrate at least 1000 Å into deposited films and thus suggest that voids are interconnected by microscopic pores.
Output power fluctuations in a high-pressure cw CO2 laser
Authors: Hishii M. , Nagai H. , Nagai A. , Akiba T.
Published: February 2003

Large fluctuations of output power have been observed above a certain level of the radiation power accumulated inside the laser cavity. These fluctuations can be effectively suppressed by circulating the gas mixture through an unexcited region between the active medium and one of the cavity mirrors, or by removing CO2 molecules from the gas mixture in the unexcited region. Experimental evidence indicates that the fluctuations are due to the absorption of intracavity radiation by the CO2 molecules contained in that region.
Dynamics of CO2 laser heating in the processing of silicon
Authors: Siregar M. R. T. , Lüthy W. , Affolter K.
Published: February 2003

The optical transmission of commerical Si wafers was measured at the wavelength of 10.6 μm as a function of temperature in the interval from about 78 to 850 K. We show that the absorptivity of Si increases with the sample temperature. This temperature dependence is explained by free-carrier absorption. A transmission measurement at 10.6 μm wavelength has been used to monitor the temperature of a Si sample as a function of time during cw laser heating.
Kinetics of the XeCl (B→X) laser
Authors: Finn T. G. , Chang R. S. F. , Palumbo L. J. , Champagne L. F.
Published: February 2003

Formation and quenching processes of the XeCl (B) state have been investigated. Mixtures of Ne/Xe/HCl have been irradiated by an electron beam of 0.6 μsec duration. The results indicate that the formation efficiency of the XeCl (B) and (C) states are 143%and 31%, respectively. If these states are closely coupled, the ultimate efficiency of the XeCl (B→X) laser is 174%. Two-body quenching by neon is the major loss process. At a pumping current of 7 A/cm2, electron mixing of the B and C states is negligible; however, electron quenching may be present, and at most a 20% effect.
Ohmic contact formation on InP by pulsed laser photochemical doping
Authors: Deutsch T. F. , Ehrlich D. J. , Osgood R. M. , Liau Z. L.
Published: February 2003

Pulsed UV laser photolysis of metal alkyls combined with laser heating has been used to introduce Cd or Zn into p-InP. Ohmic contacts with specific contact resistances of 1.9×10−4 Ω cm2 have been formed using a pulsed ArF laser to photolyze Cd(CH3)2.
The effect of neutron irradiation upon the superconducting critical temperature of some transition-metal carbides, nitrides, and carbonitrides
Authors: Dew-Hughes David , Jones Robert
Published: February 2003

Samples of TiN, NbC, and Nb(CN) have been irradiated to various neutron doses in the Brookhaven High Flux Beam Reactor. Their superconducting critical temperatures are reduced at a rate which is much less than that for similarly irradiated high-Tc A15 superconductors. A dose of 1.5×1020 n/cm2 (E≳1 MeV) causes a reduction in Tc of 6–27%. This reduction may be explained in terms of the production of metal-lattice vacancies.
Suppression of higher harmonic generations of SAW in LiNbO3
Authors: Lee J. , Singh M. P. , Zucker J.
Published: February 2003

ZnO thin-film loading of YZ-LiNbO3 is used to suppress all the harmonic generations of surface acoustic waves (SAW’s) in the substrate. An optical probing technique is used to measure the intensity variations of the harmonics as a function of acoustic power. Only the first-order diffracted light intensity is observed owing to the suppression of higher harmonic generations of SAW’s. This linearization of the first-order diffracted light intensity versus acoustic power is found to be independent of the interaction length (up to 5 mm) and the acoustic power (up to 4.3 W). The attenuation of SAW’s on YZ-LiNbO3 with a 2-μm ZnO layer was measured to be about 5 dB/cm at 325 MHz.
Hydrogenated amorphous-silicon thin films produced by ion plating
Authors: Cocks Franklin H. , Scharman Alan J. , Jones Phillip L. , Cogan Stuart F.
Published: February 2003

Ion plating techniques have been used to produce amorphous-silicon thin films which contain up to 25 atomic percent hydrogen. The Si–H bond stretching mode observed for hydrogenated amorphous-silicon thin films produced by glow-discharge decomposition methods is also observed for these ion-plated films. Optical absorptivity measurements for ion-plated films give band-gap values between 1.58 and 1.90 eV.
Direct writing of regions of high doping on semiconductors by UV-laser photodeposition
Authors: Ehrlich D. J. , Osgood R. M. , Deutsch T. F.
Published: February 2003

The direct doping of InP with variable Cd concentrations has been demonstrated in a maskless process with micrometer-scale spatial control. The process makes use of cw UV-laser photodeposition of the dopant on a laser-heated surface.
An amorphous SiHx-ferroelectric image scanner
Authors: Lemons R. A.
Published: February 2003

By sputtering an amorphous SiHx photoconductor onto a gadolinium molybdate crystal, the voltage required to move a ferroelectric domain wall can be modulated with a light pattern. This allows the light pattern to be converted to a voltage waveform. Since the domain wall is less than 100 nm wide, a high-resolution image line scan is produced without fabricating a fine pattern in the device surface. Using a constant current source to drive the domain wall, the fabricated devices resolve up to 400 lines/mm. This limitation is due to the device capacitance rather than domain-wall width or current spreading in the photoconductor.
Measurement of high pressure induced in water by a CO2 laser pulse
Authors: Giovanneschi P. , Dufresne D. , Caressa J. P. , Bournot Ph.
Published: February 2003

The vaporization and thermoelastic pressures induced in water by a high-energy CO2 laser pulse are measured as a function of the laser intensity. Below the air/water interface breakdown threshold, the vaporization peak pressure increases as the (6)/(5) power of the laser intensity and as the (2)/(3) power of the laser intensity above the breakdown threshold. The thermoelastic peak pressure is proportional to the laser power.
Formation of p+-p−-n− junctions in InP by Cd diffusion
Authors: Chin A. K. , Dutt B. V. , Temkin H. , Bonner W. A. , Roccasecca D. D.
Published: February 2003

A study was made of the diffusion of Cd into nominally undoped (4×1016 cm−3) n-type InP using elemental sources consisting of (Cd and In) or (Cd and P). Two diffusion fronts whose depths are controlled by the amount of P or In in the diffusion source were delineated by etching. Electron beam induced current profiles and photoluminescence measurements revealed the formation of a  p+- p−- n− junction, with the  p− region bounded by the two diffusion fronts. Mesa p+- p−- n− diodes, 150 μm in diameter, fabricated from a wafer with the p+- p− and p−- n− junctions at 3.1 and 20.0 μm, respectively, have reverse breakdown voltages between 90 and 220 V and reverse leakage currents from 5 to 10 pA at half breakdown. The I-V characteristics of these p+-p−-n− diodes exceed those of state of the art, abrupt p+-n− InP avalanche photodiodes because of the formation of the p− region.
Electro-optic frequency- and polarization-modulated injection laser
Authors: Reinhart F. K. , Logan R. A.
Published: February 2003

A novel class of frequency- and polarization-modulated GaAs-AlxGa1−xAs double-heterojunction lasers is described. The lasers are formed by the monolithical integration of an optical amplifier, an electro-optic polarization modulator, and a polarizer. Frequency modulation of 20 Å/V and polarization rotation of 40° has been achieved by the linear electro-optic effect.
The optical band gap of hydrogenated amorphous-boron thin films: The effect of thermal treatment
Authors: Cocks Franklin H. , Jones Phillip L. , Dimmey Louis J.
Published: February 2003

Hydrogenated amorphous-boron thin films produced by glow-discharge decomposition of a gas mixture of 3.1 vol. % diborane and 96.9 vol. % hydrogen have been heat treated at 360 and 400 °C. The resulting absorption coefficients and optical band gaps have been measured as a function of heat-treatment time and temperature. Both the absorption coefficients and the optical band gaps of these films can be drastically changed by such treatments. Thermal treatment at 400 °C for 200 h results in a systematic decrease in the optical band gap from 2.19 to 0.90 eV. From quantitative hydrogen analyses it is shown that hydrogen evolution during heating plays a strong role in reducing the apparent optical band gap. These results indicate that it might be possible to optimize theoretical amorphous-boron thin films through the tailoring of the optical band gap by such thermal treatment.
Dislocation motion and solid-state turbulence
Authors: Herring C. , Huberman B. A.
Published: February 2003

We show that, under suitable conditions, the dynamics of crystal dislocations in the presence of acoustic fields can lead to chaotic behavior. We suggest experiments involving the motion of straight dislocation segments against Peierls-Nabarro forces and the optical modes of partials and discuss the detection of the turbulent regime.
Improved characterization of the Si-SiO2 interface
Authors: Su P. , Sher A. , Tsuo Y. H. , Moriarty J. A. , Miller W. E.
Published: February 2003

Refined quasistatic and conductance methods, based on effectively thin composite insulating layers, low-carrier-concentration bulk semiconductors, and low-level illumination, have been applied to an improved characterization of the (100) Si-SiO2 interface. Accurate measurement of both the total density of interface states and its major components as a function of energy in the forbidden gap have been made over four decades (1010–1014 states/eV cm2) on a single sample. The normal U-shaped density of states is here resolved into separate valence- and conduction-band-derived contributions as well as impurity-derived contributions corresponding to concentrations on the order of 20 ppm at the interface.
Thermo-optical spectroscopy: Detection by the ’’mirage effect’’
Authors: Boccara A. C. , Fournier D. , Badoz J.
Published: February 2003

A new thermo-optical method based on the sensitive detection of thermal gradients adjacent to heated sample surfaces is described. Room- and low-temperature experiments were performed using this technique, and its advantages over different methods are discussed.
Photodissociation of HgCl
Authors: Julienne P. S. , Konowalow D. D. , Krauss M. , Rosenkrantz M. E. , Stevens W. J.
Published: February 2003

Transition moments and energies have been calculated for the X-A, bound to continuum, transition in HgCl. The photodissociation cross section at the peak (∼20 000 cm−1 or 500 nm) is 1.2×10−18 cm2 at 600 K. The laser energy 17 921 cm−1 or 558 nm) for the B-X transition is close to the peak energy, and a significant absorption will result from a buildup in the concentration of X state HgCl in the course of exciting the laser media. This absorption is suggested as an explanation for the low extraction efficiencies observed for HgCl lasers.
Surfaces for radiative cooling: Silicon monoxide films on aluminum
Authors: Granqvist C. G. , Hjortsberg A.
Published: February 2003

Efficient radiative cooling is feasible with surfaces which radiate predominantly in the 8–13-μm wavelength range, where the atmosphere emittance is low. The desired reflectance profile was approximated with 1.0 μm of SiO evaporated onto Al. It results from strong lattice absorption in SiO in conjunction with destructive interference. Refrigeration to 40 K below the ambient appears to be possible under suitable climatic conditions.
Self-aligned thin film structures with 1000 Å resolution
Authors: Howard R. E. , Hu E. L. , Jackel L. D.
Published: February 2003

A two-level e-beam resist process is described which is capable of producing features under 1000 Å in size. The process is compatible with oblique evaporation technique so that high-accuracy alignment can be obtained in multiple-layer device structures. Tunnel junction structures with areas as small as 10−10 cm2 have been fabricated. The estimated capacitance for such junctions is <10−15 F. Such structures have application in low-capacitance Josephson logic circuits. The process is also applicable to fabrication of submicron MOM diodes and other devices which can be made using a lift-off technique.
Formation process of oxide precipitates in Czochralski-grown silicon crystals
Authors: Shirai Shoza
Published: February 2003

Swirl-free silicon crystals were grown, and the relation between growth condition and oxide precipitates (1100 °C) has been studied by the Secco etching technique and x-ray topography. It was found that precipitates are formed at very high densities in crystals which were grown by introducing temperature fluctuations during the growth. They are located in the seed side of a remelt boundary on which a new growth circle started after each remelting. These results are similar to those for swirl defects in float-zoned crystals. It is proposed that the precipitates are originated from liquid drops which are formed in interface regions superheated by temperature fluctuations during the growth.
Zn diffusion into GaAs by a two-temperature method
Authors: Hasegawa Osamu , Namazu Ryosuke
Published: February 2003

Low-concentration diffusion of Zn into GaAs has been performed using a closed-tube two-temperature method whereby the ZnAs2 diffusion source and the GaAs wafer are placed in the low and the high temperature zones, respectively. Surface hole concentration decreases as the wafer temperature rises, mostly due to the temperature dependence on the equilibrium constant for the reaction which Zn incorporates into the Ga site. The junction depth is heavily dependent on the source temperature. Highly efficient LED is obtained by a two-temperature diffusion method.
Reduction of oxides on silicon by heating in a gallium molecular beam at 800 °Ca)
Authors: Wright Steve , Kroemer Herbert
Published: February 2003

Nonvolatile SiO2 on Si is reduced to elemental Si and to volatile SiO, by exposing the oxidized Si to an atomic Ga beam in vacuum, at a temperature as low as 800 °C. The SiO and the Ga2O form in the process, and the excess Ga evaporates at this temperature, leaving behind a clean and damage-free surface.
Chromium concentrations, depth distributions, and diffusion coefficient in bulk and epitaxial GaAs and in Si
Authors: Wilson R. G. , Vasudev P. K. , Jamba D. M. , Evans C. A. , Deline V. R.
Published: February 2003

Implantation of 200-keV chromium fluences from 4.5×1012 to 1.0×1015 cm−2 and SIMS profiling were used to measure the atom densities and depth distribution of Cr in bulk GaAs (Cr), in undoped liquid-phase epitaxial GaAs grown on a GaAs(Cr) substrate, and in Si. The Cr atom density in both GaAs(Cr) substrates was ∼1.6×1017 cm−3. The background-limited detection sensitivity of SIMS for Cr in GaAs was ⩽3×1015 cm−3. Chromium outdiffused into the epitaxial layer during growth at 800 °C. The diffusion coefficient for CR at 800 °C in GaAs was determined to be 6.7×10−12 cm2/sec. Channeling tails were observed for the Cr implanted in Si and in the undoped epitaxial GaAs, but not in the bulk GaAs(Cr). Ranges, range straggles, and other Pearson IV moments for the implanted Cr distributions are given.
Step-edge fabrication of ultrasmall Josephson microbridges
Authors: Feuer M. D. , Prober D. E.
Published: February 2003

A technique for producing ultrasmall variable-thickness Josephson microbridges for high-frequency applications is described. A two-dimensional shadowing technique is employed with self-aligning photolithographic and reactive-ion milling processes to pattern the substrate with high-resolution steps. Step heights normal to the substrate are used to determine microbridge dimensions. Lead-alloy microbridges with resistances ≈10 Ω and dimensions of 50 nm have been produced, and their electrical properties studied. The limits on device size are in the range 10–20 nm. Heated-substrate deposition of high-Tc superconductors is compatible with this technique.
Oscillator and oscillator-amplifier experiments with an HgBr2/HgBr dissociation laser
Authors: Schimitschek E. J. , Celto J. E.
Published: February 2003

Using steady-state approximations to describe the performance of an HgBr* (B→X), uv-preionized discharge laser oscillator and amplifier, values are derived for small-signal gain g0, absorption α0, and saturation flux Isat. The averaged best fit of the experimental data to the theoretical expressions is found for g0=6.6%/cm, α0=0.35%/cm, and Isat =200 kW/cm2 for the case when the buffer gas consists of 900 Torr Ne+100 Torr N2.
Parametric difference frequency generation in a three-dimensional LiNbO3 optical waveguide
Authors: Uesugi Naoshi
Published: February 2003

Difference frequency generation in a three-dimensional LiNbO3 optical waveguide is experimentally shown using a cw Rhodamine 6G dye laser and a Nd:YAG laser at 1.318 μm. The generated difference frequency wavelength was tuned from 1.035 to 1.19 μm. The output power of the difference frequency wave was 2.4 μW at 1.035 μm, with a pumping dye laser power and an idler Nd:YAG laser power of 70 and 1.7 mW, respectively.
Injection and containment of an unneutralized electron cloud in a bumpy toroidal magnetic field
Authors: Fisher A. , Gilad P. , Goldin F. , Rostoker N.
Published: February 2003

We report on the successful injection, compression, and confinement of an unneutralized electron cloud in a multiple-mirrored toroidal magnetic field geometry. About 2×1012 electrons were compressed to maximum energy of 500 keV. The lifetime of the cloud was limited by the decaying magnetic field. During its lifetime, the cloud was found to perform m=1 diocotron oscillations. Two injectors were operated in two separate mirror cells, and their mutual interaction was studied.
Carbon segregation and arc damage of tungsten electrodes
Authors: Ostermayer F. W. , Koch F. B.
Published: February 2003

Eruptions that occur on tungsten electrodes after repeated 35-A arcs of 1.44-msec duration have been studied with a scanning Auger microprobe and found to contain high concentrations (20–30 at.%) of carbon. This is much greater than the average carbon concentration in the tungsten and is in the vicinity of the W-W2C eutectic at 25 at.%. Further evidence that the eruptions are rich in W2C comes from their solubility in hot HNO3. Therefore it appears that carbon progressively segregates in the arc spots due to its low solid solubility in tungsten and the resultant lowering of the melting point is responsible for the eruptions.
Crystalline phase transition in the copolymer of vinylidenefluoride and trifluoroethylene
Authors: Tajitsu Y. , Chiba A. , Furukawa T. , Date M. , Fukada E.
Published: February 2003

The measurement of the temperature dependence of elastic, dielectric, and piezoelectric constants for the film of 55/45% VDF-TrFE copolymer suggests that the Curie temperature exists at about 70 °C. The lattice spacing sharply changes at a temperature range from 55 to 75 °C. The remanent polarization is also determined from the D versus E hysteresis loop below 75 °C. It is found that the spontaneous strain in crystal lattice is linearly related to the square of remanent polarization. The transition is ascribed to electrostriction due to dipolar orientation.
MOS rib waveguide polarizers
Authors: Reinhart F. K. , Shelton J. C. , Logan R. A. , Lee B. W.
Published: February 2003

The transmission properties of single-heterostructure GaAs-AlxGa1−xAs rib waveguides (RWG) clad with thin anodized oxides (0–200 Å) covered by gold (MOS structures) are investigated both theoretically and experimentally. Efficient polarizers having extinction ratios of 35 dB and insertion losses <1 dB can be achieved with short (250 μm) polarizing sections. Details of attenuation characteristics depend on the dielectric constants and can be used to investigate the dielectric interface properties of MOS structure.
Influence of fluorine on oxidation-induced stacking faults
Authors: Isomae S. , Tamura H. , Tsuyama H.
Published: February 2003

To investigate the influence of fluorine on OISF (oxidation-induced stacking faults), samples in which fluorine or BF2 ions were implanted into SiO2 film on the Si substrates were prepared. These samples were oxidized in dry O2 or wet O2 at 1100–1200 °C and subsequently the length of OISF was examined using Secco etchant. Shrinkage of OISF was observed in dry O2 oxidation. On the other hand, in wet O2 no shrinkage of OISF was observed. These results can be explained by differences in the fluorine concentration profile in the oxide. It was further concluded that fluorine in the oxide near the SiO2-Si interface plays an important role in the shrinkage of OISF.
Segregation and increased dopant solubility in Pt-implanted and laser-annealed Si layers
Authors: Cullis A. G. , Webber H. C. , Poate J. M. , Simons A. L.
Published: February 2003

Q-switched laser irradiation has been used to melt and recrystallize amorphous Pt-implanted layers formed on the surface of Si single crystals. While the Pt segregated to the surface by an effect related to zone refining, the final impurity depth distribution depended upon substrate temperature in the range 77–620 °K. This observation is correlated with calculations of changing melt dwell times and resolidification velocities. The nonuniform lateral distribution of the segregated Pt at the Si surface is believed to be controlled by constitutional supercooling occurring in the resolidifying melt. In addition, Pt exhibited considerable substitutionality in the Si lattice after laser annealing, corresponding to an effective solubility enhancement of 3 orders of magnitude. This phenomenon is correlated with solute trapping and melt viscosity effects occurring during resolidification.
Monochromatic x-ray images of x-ray emitting sources
Authors: Fraenkel Benjamin S.
Published: February 2003

A method is demonstrated for obtaining monochromatic aberration-free images of x-ray emitting sources, through the process of double Bragg reflection. Space-resolved ion and temperature distribution in hot plasmas may therefore be obtained.
Electron beam annealing of ion implanted Al
Authors: Wampler W. R. , Follstaedt D. M. , Picraux S. T.
Published: February 2003

Pulsed electron beam annealing of Zn- and Sb-implanted Al has been investigated with ion backscattering and transmission electron microscopy. The impurity redistribution produced by 50-nsec pulses with deposited energies of 1.1 and 1.6 J/cm2 is shown to be due to diffusion in the liquid phase and provides an estimate of the melt time (∼300 nsec for 1.6 J/cm2). Comparison with conventional thermal annealing further supports an interpretation with uniform diffusion in the near-surface region. In addition, precipitation of AsSb was found to occur within the liquid phase, which is consistent with the Al-Sb phase diagram.