bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of molecular beam characteristics for condensable molecules by optical interferences
Authors: Woznyj M. , Feldmeier F. , Hofmann A.
Published: February 2003

A method is presented which allows the determination of the characteristics of effusive molecular beams formed by heavy molecules. It is based on condensing the beam molecules on a cooled metal surface and measuring the thickness of the condensed layer by means of interference when the layer is lighted with monochromatic light. The information about the beam characteristics is provided by the growth of the layer thickness. The results in the case of the investigated benzene beam are in agreement with the theoretical predictions of a model of molecular beam formation by effusive sources, as far as this model can be assumed to be correct.
Generation and measurement of dc electric fields with space charge
Authors: Misakian Martin
Published: February 2003

Characterization of the electrical environment in the vicinity of high voltage dc transmission lines requires measurement of a number of electrical parameters associated with the lines. These parameters include the electric field strength with significant space-charge contributions. This report describes an experimental effort to generate known dc electric fields containing controlled amounts of space charge. An apparatus which has been built for this purpose is described, and two types of field probes currently used for transmission line field measurements are examined with the apparatus. Limitations on the operation of one type of probe in the presence of very large current densities are identified and discussed.
Electromagnetic scattering by a surface wave from a notch in a ground plane covered by a dielectric slab
Authors: Nevels Robert D. , Butler Chalmers M.
Published: February 2003

A notch of finite width and infinite uniform length in a perfectly conducting ground plane covered by a dielectric slab is considered. Excitation of the notch is by a surface wave with a transverse magnetic (TM) mode of propagation in the grounded dielectric slab. An integral equation is derived in terms of the unknown tangential electric field in the aperture of the notch. A scattering parameter representation of the surface wave fields is also presented.
Parametric study of the 357.7-nm oscillation in a TE (transversely excited) N2 laser
Authors: Mitani Tetsuya
Published: February 2003

New experimental results on the factors affecting the 357.7-nm oscillation in a Blumlein-driven N2 laser are presented and compared with the theoretical considerations. The laser output at 357.7 nm is enhanced not only by adding a foreign gas but also by reducing the amount of preionization, decreasing the repetition rate of discharge, and lowering the inductance of the discharge circuit. On the basis of the assumption that these actions serve to shorten the rise time of discharge current in their common function, such experimental results are explained fairly well.
Thermal impedance of diode lasers: Comparison of experimental methods and a theoretical model
Authors: Manning Joanne S.
Published: February 2003

The thermal impedances of double heterostructure, oxide isolated, stripe geometry diode lasers were measured and compared to a calculated value from a theoretical heat-flow analysis. The lasers had a stripe width of 8 μm and a cavity length of 250 μm, and were bonded with indium solder to a gold/nickel plated copper block. The measurement techniques were based upon the variation with active region temperature of four different device parameters: the terminal voltage, the emitted optical power, the longitudinal-mode spectrum, and the lasing threshold current. As predicted by the theoretical analysis, the thermal impedance measurements based upon the various parameters yielded the same measured thermal impedance, indicating that each parameter responded to the same average active region temperature. The range of values measured for different diodes was 33 to 79 °C/W, compared to the theoretically calculated value of 25 to 30 °C/W. The wide range of measured values is attributed to irregular conditions associated with the indium bond.
Enhancement of prism coupling efficiency in uniform optical waveguides: A correction
Authors: Revelli J. F.
Published: February 2003

The subject of prism coupling into uniform clad waveguides in the strong coupling regime is revisted and coupling efficiencies are recalculated for the same numerical example presented in previous work. Contrary to former results, cladding is found to improve coupling efficiency significantly: increasing from 6% for no cladding to more than 70% for cladding just above cutoff. The largest source of error in the previously reported work was found to be improper normalization of the so-called ideal beam profile function. This error is largest for waveguides with no cladding.
Improved formula for continuous-wave measurements of ultrasonic phase velocity
Authors: Chern Engmin J. , Cantrell John H. , Heyman Joseph S.
Published: February 2003

An improved formula for continuous-wave ultrasonic phase velocity measurements using contact transducers is derived from the transmission line theory. The effect of transducer-sample coupling bonds is considered for measurements of solid samples even though it is often neglected because of the difficulty of accurately determining the bond thickness. Computer models show that the present formula is more accurate than previous expressions. Laboratory measurements using contacting transducers with the present formula are compared to measurements using noncontacting (hence effectively correction-free) capacitive transducers. The results of the experiments verify the validity and accuracy of the new formula.
The response surface in elastic wave scattering
Authors: Brill D. , Gaunaurd G. , Überall H.
Published: February 2003

We study the normal-mode amplitudes for the scattering of (compressional and shear-type) elastic waves returned by a fluid-filled spherical cavity in a solid in the absence and presence of mode conversion, and examine their unitarity properties. The moduli of the resonance portions of these amplitudes are exhibited in the form of a two-dimensional ’’response surface’’ in a three-dimensional graph, where the two independent variables are (nondimensional) frequency and mode order. For various combinations of incident and scattered waves we note, display, and explain the various distinctive features of the response surface, namely, the loci of the zeroes, the series of ridges which give rise to modal resonances and to Regge poles (circumferential waves), and a series of tips along each ridge, which correspond to resonances in the circumferential waves due to phase matching. These informative features, graphically displayed at a glance in the plots of the response function, are useful in the interpretation of the scattering process taking place around fluid-filled cavities in solids, and in the identification of the material composition of the cavity contents, if the fillers were not known a priori.
Surface acoustic wave attenuation by a thin film
Authors: Snider Dale R. , Fredricksen Hans P. , Schneider Susan C.
Published: February 2003

The attenuation of Rayleigh-type waves traveling in a layered film-substrate combination is calculated by including a loss term due to viscous damping in the equation of motion for the film. The attenuation can thus be readily obtained without heuristic arguments by an analytic continuation of the analysis for the velocity of a surface wave without damping. Comparison to previous models is made for various film and substrate materials.
Surface acoustic wave properties of (Pb,Ln)(Ti, Mn, In)O3 ceramics (Ln = La and Nd)
Authors: Ito Yukio , Takeuchi Hiroshi , Nagatsuma Kazuyuki , Jyomura Shigeru , Ashida Sakichi
Published: February 2003

The surface acoustic wave properties of PbTiO3 ceramics are improved. The ceramic systems investigated are (Pb,Ln)(Ti,Mn,In)O3(Ln = La,Nd). The temperature coefficients of delay time are lowered to 46×10−6/ °C, when Ln is La. A zero temperature coefficient of delay can be achieved when Ln is Nd. The Nd and In substitution also cause the electromechanical coupling factor to increase and the dielectric constant to decrease.
Radial dependence of the excitation process in a Hg ion laser
Authors: Ninomiya H.
Published: February 2003

In a He-Hg pulsed discharge, the temporal and radial behaviors of the population densities of He* (2 3S1), Hg*(6 3P0), and Hg+(7p 2P3/2) are studied experimentally in connection with the time variation of the field pattern of the laser oscillation at 615.0-nm line of Hg-II. The field pattern of the laser oscillation is explained in terms of the radial distribution of the populations of He*(2 3S1) and Hg*(6 3)P0 atoms which take part in the Penning-like excitation process.
Axial and radial segregation in metal halide arcs
Authors: Stormberg H. -P.
Published: February 2003

A theoretical model for the axial segregation in cylindrical high-pressure mercury discharge lamps with metal halide additives is evaluated regarding various diffusion effects and the vertical convection of mercury. The model is applied to the case of NaI and TlI additives and shows the strong influence of ambipolar diffusion on the axial segregation especially for Na, the demixing of which is always more pronounced than that of Tl and I. Furthermore, the model shows the strong influence of the lamp radius and the mercury pressure on the segregation behavior. The numerical results are in agreement with particle densities obtained spectroscopically.
Electromagnetic decay into a surface plasma wave and an ion acoustic surface wave in a semi-infinite plasma
Authors: Yasumoto K.
Published: February 2003

The decay instability of a high-frequency surface plasma wave and a low-frequency ion acoustic surface wave, which arises when an intense electromagnetic plane wave is incident perpendicularly on an unmagnetized semi-infinite plasma from a vacuum, is investigated on the basis of two-fluid hydrodynamics for warm electrons and cold ions. The growth rate for the instability and the threshold amplitude of the incident wave are determined. The growth rate is compared numerically with that for a similar decay instability of the corresponding volume-wave modes. In contrast to the ’’volume’’ decay instability, the present one gives an appreciable growth rate even if the frequency of the incident wave is lower than the electron plasma frequency.
Theoretical quantities of some parameters in the cathode-fall region of a copper vacuum arc
Authors: Kubono Takayoshi
Published: February 2003

The paper gives a survey of numerical values of the most important parameters at the copper arc-cathode root and in the cathode-fall region. The radius and the temperature of the arc-cathode root, the electron current fraction, the electric field, the thickness of the cathode-fall region, and the atom density in this region are theoretically calculated and shown as a function of the arc current. Furthermore, there is a short section describing the suggestion that after neutralization of ions on the boiling surface of the cathode root, all of the resulting atoms may be reflected away into the cathode-fall region.
Multicolor fluorescent display by scattering states in liquid crystals
Authors: Sato S. , Labes M. M.
Published: February 2003

Cholesteric and nematic liquid-crystal electro-optic cells are described which function as both UV shutters and as tunable fluorescent emitters ( shutter cells ). Two-color displays of blue-green, blue-red, or green-red are achieved in the double-layered structure of the shutter cell with an external passive fluorescent element. Contrast ratios of about 5 in these two-color pairs are achievable by electrically switching the shutter cell. Display characteristics for several fluorescent guest materials are measured and their dependence on various system parameters is discussed. Multicolor fluorescent displays are made by using a triple-layered structure of shutter cells and passive elements.
Precipitation of oxygen in silicon: Some phenomena and a nucleation model
Authors: Hu S. M.
Published: February 2003

This paper reports some phenomena of the nucleation of oxygen precipitates in silicon, and proposes a nucleation model consistent with these observations. In addition to the principal tool of infrared absorption for the measurement of dissolved oxygen concentrations, the distribution of the dissolved and the precipitated oxygen was characterized by a method combining thermal conversion and spreading resistance profiling, a method combining thermal conversion and copper plating, and a selective etching. Heat treatments were carried out in argon ambients at temperatures from 800 to 1150°C, for time up to 96 h. In many cases samples from seed-end segments of Czochralski crystals, with uniform initial oxygen distribution, exhibited alternating zones of fast and slow precipitation. Both the low density and the clustering aspects of the precipitates in the slow precipitation zones are reminiscent of precipitates formed in oxidizing ambients I previously reported. The density of precipitates was observed to increase with annealing time, and for sufficiently long time, with the decrease of annealing temperature. In sequential annealing processes, a low-temperature preanneal was found to accelerate the precipitation in a subsequent higher-temperature anneal. These two phenomena are evidence of a homogeneous nucleation process. It was also observed that a high-temperature preanneal tended to irreversibly retard the precipitation in a subsequent lower-temperature anneal. Both this phenomenon and the zonal variation of precipitation rates are not expected from the conventional concept of homogeneous nucleation, which involves only the agglomeration of solute atoms. However, both can be explained by a modified homogeneous nucleation model that involves both the oxygen atoms and certain active centers, most probably small vacancy complexes. These small vacancy complexes are often incorporated in striae during crystal growth, and are susceptible both to annihilation by oxidation induced excess self-interstitials, and to breakup by high-temperature preanneals. A surface proximity effect is also reported, in which oxygen in a surface zone immediately below the out-diffusion zone precipitated out faster than in bulk.
Characterization of polished (111) silicon crystal surface by diffuse x-ray scattering
Authors: Yasuami S. , Harada J.
Published: February 2003

The diffuse x-ray scattering due to small defects in a silicon single crystal, which has been found by Yasuami, Harada, and Wakamatsu [J. Appl. Phys. 50, 6860 (1979)] has been identified as coming from a thin surface layer of the crystal. The small defects, therefore, cannot be B-swirl defects and do not have any correlation with crystal growth methods, floating zone or Czochralski zone, and with growth direction. They are considered to be introduced during the surface polishing process and to exist in the surface layer of about 150 μm thick. For detecting such small defects, diffuse x-ray scattering is more advantageous than the conventional rocking curve measurement.
Internal friction peaks in cold-worked and hydrogen-charged nickel
Authors: Tanaka K. , Ryonai H. , Yamada M.
Published: February 2003

Internal friction measurements are made on deformed and hydrogenated Ni at frequencies of 2 Hz, 800 Hz, and 30 kHz over the temperature range between 4.2 and 373 K. Two kinds of relaxation peaks Pd and PdH accompanied by clear ΔM effects are commonly observed. Pd peak is generated at low temperature only by plastic deformation in uncharged Ni. Electrolytic charging with hydrogen suppresses this peak but instead induces PdH peak at a temperature well above Pd peak. On aging (outgassing) at temperatures between room temperature and 473 K, Pd further diminishes temporarily, but recovers to the original height thereafter; conversely, PdH first grows to a maximum height and then decays. These aging characteristics are related with nonuniform distributions of hydrogen in the samples. A good proportionality exists between the maximum height of PdH and the height of Pd before H charging. In fully annealed samples where Pd is absent, PdH is not generated evidently by H charging. From these results, it is concluded that Pd peak is ascribable to the dislocation relaxation peak of the Bordoni type, while PdH peak to the cold-work peak involves the interaction between hydrogen atoms and dislocations.
Transition temperatures and heats of crystallization of amorphous Ge, Si, and Ge1−xSix alloys determined by scanning calorimetry
Authors: Fan John C. C. , Anderson Carl H.
Published: February 2003

The transition temperatures (Tt) and heats of crystallization (ΔH) of a-Ge, a-Si, and a-Ge1−xSix films deposited by rf sputtering have been measured by differential scanning calorimetry (DSC). Both Tt and ΔH (per gram) increase linearly with x in the alloy system. Overlapping exothermic multiple peaks are observed in the DSC traces of a-Ge and a-Si samples prepared at high deposition rates, suggesting that multiple amorphous configurations may coexist in these materials.
Trapping of Sb by TaC and Cu precipitates in ion-implanted Fe
Authors: Myers S. M. , Follstaedt D. M.
Published: February 2003

Experimental evidence is presented for trapping of Sb by TaC and Cu precipitates in Fe. These processes were studied during annealing at 873 K of Fe ion-implanted with either Ta, C, and Sb, or Cu and Sb. For both precipitates the derived binding enthalpy is ∼0.4 eV when referenced to an Sb solution site in the bcc-Fe phase. It is argued that this trapping occurs at the precipitate-host interface, and that it is due primarily to the associated structural discontinuity. In the Fe-Cu-Sb alloys, trapping was accompanied by two other processes which immobilize Sb, namely, dissolution into the fcc-Cu phase and formation of β-Cu3Sb. The trapping effects observed in these studies are of potential significance for the control of Sb embrittlement in ferritic steels.
Structural and photoluminescent properties of GaxIn1−xP(x≊0.5) grown on GaAs by molecular beam epitaxy
Authors: Roberts J. S. , Scott G. B. , Gowers J. P.
Published: February 2003

Heteroepitaxial films of (001) oriented GaxIn1−xP(x≊0.5) deposited on GaAs buffer layers have been grown by molecular beam epitaxy (MBE). Other than dislocations threading from the substrate, 1-μm-thick alloy films were free of extended defects in TEM examination for a range of 300-K misfit strains between −7×10−4 and 1.4×10−3. In contrast to VPE grown GaxIn1−xP, the absence of misfit related dislocations over such a range of misfit strains is believed to result primarily from the low MBE growth temperatures (670–790 K). TEM micrographs recorded using bright-field, two-beam conditions showed a grainy texture on the scale of 100 Å which may arise from group III sublattice inhomogeneity. Similar contrast is observed in high luminescence efficiency LPE GaxIn1−xAsyP1−y and VPE Ga0.5In0.5P. The photoluminescent (PL) efficiency from nominally undoped, 1-μm-thick films of MBE GaxIn1−xP(x≊0.5) was generally constant across typical wafer widths of 2.5 cm having a composition span of 0.02 in x. Deviations from this behavior may have resulted from variations in the group V to group III flux ratio from layer to layer. The maximum, external PL efficiency for near band edge emission for 1-μm-thick layers was 1.8×10−5. This low value is not due to competing radiative transitions between 1.9 and 0.5 eV since the low temperature PL spectra consist only of two dominant, near band edge peaks whose excitation dependence suggests they are donor band and donor acceptor in nature. They are probably associated with C and Si impurities, which have been detected by PL in the GaAs buffer layer. Both the 300 and 11-K PL linewidths of nominally undoped films are broader than expected from thermal considerations alone and may reflect group III sublattice disorder. The dispersion of the refractive index of Ga0.51In0.49P has been determined in the range 700–1700 nm.
GaInAs-AlInAs structures grown by molecular beam epitaxy
Authors: Ohno H. , Wood C. E. C. , Rathbun L. , Morgan D. V. , Wicks G. W. , Eastman L. F.
Published: February 2003

Growth of GaInAs and A1InAs by molecular beam epitaxy on idium phosphide substrates is reported. Unintentionally doped, closely lattice matched GaInAs layers were n-type with μ300 up to 8800 cm2 V−1 s−1 and n as low as 1×1016 cm−3 whereas undoped A1InAs layers were typically high resistance. 2-MeV Rutherford backscattering showed good GaInAs crystal quality although the A1InAs was somewhat disordered. Evidence for cation exchange at interfaces and surface accumulation of indium was evident from both RBS and sputter Auger profiles. In situ grown A1 films on A1InAs showed an effective barrier height∼0.8 eV from 1/C2 V s V curves, however attention to the forward I-V characteristics indicated lower values. DLTS results indicate the GaInAs to be virtually trap-free but that A1InAs has high deep level concentrations owing to low growth temperatures. Good photoluminescent efficiencies were demonstrated for GaInAs layers, however, poor results were obtained for A1InAs.
Gold-aluminum thin-film interactions and compound formation
Authors: Majni G. , Nobili C. , Ottaviani G. , Costato M. , Galli E.
Published: February 2003

Phase formation has been studied in Au-Al thin-film interactions by means of 4He+ MeV backscattering and x-ray diffraction techniques. The films were annealded at temperatures low enough for no liquid phase formation. Au4Al, Au5Al2, Au2Al, AuAl, and AuAl2 were detected from samples prepared by depositing the exact stoichiometry quantities of Au and Al. The phase formation sequence was determined. The first phase formed is Au5Al2; the others are observed with the disappearence of one phase previously formed. For instance, Au4Al grows only when all Al is reacted and, on the other hand, AuAl2 when all Au is reacted. The sequence of the phases in the Au-Al interactions cannot be interpreted on the basis of pure thermodynamic or kinetic arguments and a composite mechanism is proposed.
Ion beam oxidation
Authors: Harper J. M. E. , Heiblum M. , Speidell J. L. , Cuomo J. J.
Published: February 2003

We describe a new technique for controlled oxide growth using a directed low-energy ion beam. The technique is evaluated by fabricating Ni-oxide-Ni and Cr-oxide-Ni tunneling junctions, using oxygen ion beams with energies ranging from 30 to 180 eV. High ion current densities are achieved at these low energies by replacing the conventional dual grid extraction system of the ion source with a single fine mesh grid. Junction resistance decreases with increasing ion energy, and oxidation time dependence shows a characteristic saturation, both consistent with a process of simultaneous oxidation and sputter etching, as in the rf oxidation process. In contrast with rf oxidized junctions, however, ion beam oxidized junctions contain less contamination by backsputtering, and the quantitative nature of ion beam techniques allows greater control over the growth process.
Voltage locking between superconducting weak links via impedance coupling
Authors: Dai Yuan-Dong , Kao Y. H.
Published: February 2003

Frequency locking effects in two interacting Josephson junctions are investigated. The junctions are described in the usual resistively-shunted-junction (RSJ) model and coupling between junctions is provided by a resonant circuit. The system can be used to simulate interactions between superconducting weak links in a resonant cavity or via a general impedance shunt. Various types of v-i curves in the voltage locking region are obtained in this calculation by using a first harmonic approximation in the high-frequency regime. Stability of order parameter phase oscillations for two identical junctions in the voltage-locked region is examined. We also show that dissimilar junctions can be synchronized in a resonant cavity using a common series bias current.
Analysis on dc characteristics of Josephson structures by the one-dimensional Green’s function method
Authors: Sugahara Masanori
Published: February 2003

Calculations on dc behaviors of Josephson structures in pure limit are made based on the one-dimensional Green’s function method. A close resemblance is found to exist between the behavior of the double-barrier-tunneling system and that of the short microbridge.
A study of the magnetic, thermal, and optical absorption properties in Ho(OH)3 crystal
Authors: Karmakar S. , Saha M. , Ghosh D.
Published: February 2003

This paper reports the result of our experimental study on the mean susceptibilities K̄ and also the molar anisotropies K∥–K⊥ between 300 and 80 K in pure Ho(OH)3 crystals. In our previous study we had shown that for Ho3+ compounds having C3h symmetry, the thermal variation of the magnetic anisotropies from 300–80 K are sensitively dependent on the detailed pattern of the crystal-field levels of the lowest 5I8 term, i.e., on the crystal-field parameters (CFP). Thus by fitting the experimental results of K̄, K∥–K⊥, K∥ and K⊥ K⊥ simultaneously in the temperature region studied, we determined the CFP for Ho(OH)3 more accurately than was possible from an analysis of spectral data which are not very informative in this crystal. We obtained B02 = 200 cm−1, B04 = −57 cm−1, B06 = −40 cm−1, and B66 = 400 cm−1. The values of B02 and B06 differed from the corresponding values for the dilute crystal, i.e., Ho3+:Y(OH)3, as reported from spectral studies. A similar type of difference in the values of CFP for dilute and pure Tb(OH)3 had also been reported earlier from spectral studies by Scott. The crystal field components of 5I8→5I4 transition in Ho(OH)3 are matched using our values of CFP. Using the crystal-field levels as obtained by us, we have shown here that the calculated values for saturated magnetization Msat, g values, and the Curie constant λ, are quite close to the observed values. From an analysis of each of the components of the total specific heat CT between 16–0.6 K, we have also shown that the magnetic specific heat has the functional behavior CM/R = (2.8±0.2)/T2, which is nearly the same as in the dilute system. The magnetic entropy SM was also calculated, and its thermal variation suggested that Ho(OH)3 behaves as a spin half system around liquid-helium temperatures but as temperature rises the contributions of the close-lying excited levels become effective and so Ho(OH)3 canot be treated as spin half system at such temperatures.
Magnetic properties and electrical resistivity of Ho-Sm alloys at low temperatures
Authors: Amin Ali Y.
Published: February 2003

Systematic investigations of Ho-Sm (1.1–16.23 at. %) polycrystalline samples are reported. Magnetization and electrical resistivity measurements as functions of field, temperature, and Sm concentration show conclusively that the anomalous increase in average moment of the sample for Sm concentrations of 1–6 at. % must be due to the addition of samarium. The critical fields at which the magnetic structure passes from paramagnetic to helical antiferromagnetic to fanlike ferromagnetic are also studied, as a function of temperature.
Experimental observation of surface modes along two parallel-axially magnetized ferrite rods
Authors: Meiri Toshimi , Mizushina Shizuo
Published: February 2003

Two pairs of resonance absorptions due to the lowest-order even 1e and odd 1o surface modes along two axially magnetized polycrystalline yttrium iron garnet YIG rods of several lengths from 3 to 25 mm have been observed in an experiment where the ferrite rods were placed in a TE10 rectangular waveguide and in a cavity coupled with a current loop. One pair is 10e and 10o resonances whose magnetization in each rod precesses in phase over the rod length. The other pair is 11e and 11o resonances due to the half-wavelength standing waves along the rods. The experimental results are compared with theory. Results of a rudimentary experiment on a magnetically variable directional coupler using these modes are also presented.
Measurement of Fe-Ga ion interchange by pulsed laser heating and fast cooling of magnetic bubble films
Authors: Petek B. , Giess E. A. , Hodgson R. T.
Published: February 2003

Relaxation times ranging from 10−4 to 10−3 s at 1200–1400 °C for Ga3+-Fe3+ site interchange have been measured by laser annealing of magnetic bubble (yttrium iron-gallium garnet) films. Laser annealing with a square pulse in time allows rapid heating and, more importantly, even more rapid cooling of the film to freeze in the high-temperature state reached. Different equilibrium site distributions and shorter relaxation times compared to previous measurements are attributed to fast oxygen diffusion out of the films, with an increased site switching rate resulting from the higher oxygen vacancy density.
Theory of the photothermal radiometry with solids
Authors: Santos R. , Miranda L. C. M.
Published: February 2003

A quantitative derivation is presented for the production of the photothermal signal in solids. Both the frequency- and time-domain responses are discussed. Typical time response curves are presented and interpreted in terms of the physical processes occurring in the photothermal emission.
Discrimination between 1/f noise models in junctions field effect transistors and metal-oxide-semiconductor field effect transistors: Numerical results
Authors: van der Ziel A. , Zijlstra R. J. J. , Park H. S.
Published: February 2003

The integrals given by Park et al. in an earlier paper [J. Appl. Phys. 52, 296 (1981)] on 1/f noise are expressed in closed forms and evaluated numerically. The results show how the field dependent mobility affects the number fluctuation model and how the field dependent mobility and the field dependence of Hooge’s parameter α affects the mobility fluctuation model. The latter effect is very strong and results in a large decrease in the noise spectrum at larger values of drain bias, when compared with the elementary theory that neglects these field dependences. For relatively short channels the mobility fluctuation model gives a peak in the noise well before saturation, in agreement with the experiments of Park et al. The effects of the field dependent mobility and of the field dependent α on the noise resistance at saturation are evaluated numerically.
Sensitivity analysis of a resonant mass gravitational wave antenna with resonant transducer
Authors: Michelson P. F. , Taber R. C.
Published: February 2003

It has become standard practice to apply optimum linear filter theory to the analysis of gravitational radiation detection systems. In this paper, we present an analysis of the signal-to-noise ratio (SNR) of a two-mode resonant detector consisting of a resonant antenna coupled to a resonant transducer. We also present a comparison of the results of this analysis to the performance fo the Stanford 4800-kg cryogenic gravity wave detector. The analysis given includes all Gaussian noise sources present in the system. These include mechanical and electrical dissipation noise sources as well as amplifier voltage and current noise. The procedure is partly numerical, but it is extremely efficient and allows optimization over a range of design parameters, rather than the case-by-case results provided by the usual modelling techniques.
The radius and the electric field of a free-burning discharge in argon
Authors: Séguin J.-N. , Novak Jaroslav P.
Published: February 2003

One of the present authors recently published a theoretical model of a two-temperature free-burning discharge. There was a need to obtain a set of measurements under conditions approximating the theoretical assumption of free cooling of the discharge column. Two accessible parameters were chosen for comparison with the theory, namely the electric field and the luminous radius. The results are in good agreement with theory and provide additional evidence that the model may be used with confidence for low-current nonequilibrium discharge studies.
Channeling effect measurements in Si by using resonant nuclear backscattering of 18–19-MeV α particles
Authors: Kudo H. , Takita K. , Masuda K. , Seki S.
Published: February 2003

18–19-MeV He++ axial channeling in Si has been measured by the conventional single-alignment method. In the backscattering spectrum, a shift of the resonant nuclear scattering peak to high-energy side was observed when an axial channeling occurred. Moreover, the peak shift became maximal for about critical-angle incidence of He++. These are direct evidences that the high-energy-loss fraction of channeled ions is considerably responsible for forming a backscattering spectrum.
Peltier-induced liquid phase epitaxy and compositional control of mm-thick layers of (Al,Ga)As
Authors: Daniele J. J. , Hebling A. J.
Published: February 2003

Epilayers of (Alx,Ga1−x)As(0.03<x<0.38) up to 1.4 mm thick were grown for the first time by Peltier-induced liquid phase epitaxy (LPE) (electro epitaxy). The epilayers were analyzed with photoluminescence microanalysis and showed thick segments (up to 600 μm) of extremely uniform aluminum composition. Compositionally graded regions varied from low XSALAS to high XSALAS in moving from the bottom to the top of the layer. The growth was performed at constant furnace temperature (T = 800 °C), with a small solution volume (15 g) and with an electric current of 10 A/cm2 as the sole driving force for the growth. The compatibility of this technique with the growth of complex multilayer structures was demonstrated.
Reply to ’’Comments on ’Raman scattering from boron-implanted laser annealed silicon’ ’’
Authors: Engstrom Herbert , Bates J. B.
Published: February 2003

Because separate experiments have shown that our samples were well annealed, we disagree with the conculsion of Forman et al. [J. Appl. Phys. 52, 4337 (1981)], that accounting for the silicon optic mode lineshape requires inclusion of the effect of incomplete annealing.
Neutron transmutation doping of silicon and other semiconducting materials
Authors: Hoffmann Hans J.
Published: February 2003

Neutron transmutation doping provides a convenient means to shift the doping level and the Fermi energy in semiconductors. In order to understand this shift quantitatively, the position of the Fermi energy EF as a function of the doping level C [EF(C) characteristic] is calculated and discussed for semiconductors with arbitrary distribution of localized levels. It is shown how the EF(C) characteristic depends on the presence of defect levels in the forbidden gap. In particular, EF is pinned at energy with large density of localized levels, corresponding to a high stability of EF against variations of C. A quantitative measure of this stability is introduced with the derivative kTdC/dEF for the EF (C) characteristic. This leads to a new method to determine experimentally the energetic position and concentrations of defects in semiconductors. The method seems to be applicable not only to crystalline semiconductors such as Si or GaAs but also to amorphous silicon.
Disappearance of impurity levels in silicon and germanium due to screening
Authors: Lowney J. R. , Kahn A. H. , Blue J. L. , Wilson C. L.
Published: February 2003

We have studied the disappearance of impurity levels in silicon and germanium due to free-carrier screening of the Coulomb field of the impurity ions. The ground-state eigenfunctions and eigenvalues have been calculated for electrons described by an ellipsoidal effective-mass Hamiltonian. A two-dimensional finite-element analysis was used to obtain the solutions. Only moderate carrier densities (1019 cm−3 for silicon and 1018 cm−3 for germanium) are needed to cause the impurity levels to disappear into the conduction band, the result at high doping densities being simply a degenerate semiconductor.
Isothermal and thermally stimulated current studies of positively corona charged polyfluoroethylenepropylene (Teflon FEP)
Authors: von Seggern Heinz
Published: February 2003

A quantitative picture of the geometric and energetic trap structure of positively corona charged polyfluoroethylenepropylene (Telfon FEP-A) was obtained by a combination of isothermal and thermally stimulated current measurements in ’’open circuit.’’In addition the heat-pulse method was used to determine the mean depth and the total charge in the sample. Application of these methods allows conclusions about the trapping probability in deep volume traps and the loss of charge in the sample due to neutralization of positive carriers at the electrodes. E/T;8172.20Jv, 73.60Hy, 71.20+c, 71.70.Ms
Electrical transport properties of p-type Pb1−xCdxTe thin films
Authors: Dawar A.L. , Taneja O. P. , Sen A. D. , Mathur P. C.
Published: February 2003

Hall coefficient and dc conductivity measurements have been made in the temperature range 77–500 K on thin exptaxial films of p-type Pb1-xCd xTe, grown by vacuum evaporation using a three-temperature technique. It has been found that the principal band gap and the mobility ratio of electron to hole increases with the increase of x. Increase of x is found to increase Te vacancies in the films which act as donors. In the low-temperature region, the ionised impurity scattering is found to be predominant, while the phonon scattering is found to limit the mobility of the charge carries at higher temperatures.
Effects of a high-temperature hydrogen anneal on the memory retention of metal-nitride-oxide-silicon transistors at elevated temperatures
Authors: Maes H. E. , Usmani S. H. , Heyns G. L.
Published: February 2003

The effects of a postnitridation high-temperature hydrogen anneal on the discharge behavior at elevated temperatures during continuous reading of the written state of p-channel metal-nitride-oxide-silicon memory transistors is studied. It is shown that by the annealing the threshold voltage decay of transistors being written and read at 125 °C can be reduced by more than 20%. This makes the information retention capability of annealed devices operating at 125 °C to be better than that of unannealed devices operated at room temperature. By using different read voltage polarities it is shown that the improved retention in annealed devices can be ascribed to the elimination of the backtunneling of holes to the Si-SiO2 interface states.
The effect of phosphorus ion implantation on molybdenum/silicon contacts
Authors: Chiang S. W. , Chow T. P. , Reihl R. F. , Wang K. L.
Published: February 2003

Formation of Mo/Si contacts by implantation of phosphorus ions was studied. The implantation was carried out at temperatures of −196, 25, and 150 °C and a fluence ranging between 1015 and 1017 ions cm−2. The morphological and structural characterizations were done with scanning electron microscopy, transmission electron microscopy, and x-ray diffraction. Hexagonal MoSi2 phase was identified in samples implanted with more than 1016 ions cm−2 at all three implantation temperatures. Traces of MoP were found in the sample implanted with 1017 ions cm−2 at 150 °C. Measured effective contact resistance showed ohmic behavior in as-implanted samples except for samples implanted with 1015 ions cm−2 at 150 °C. Smooth surfaces of implanted MoSi2 structures remained after post-implant annealing at 850 °C for 1/2 h in H2 ambient. The effect of post-implant annealing is also discussed in terms of doping, microstucture, and contact resistance.
Determination of the electrooptic coefficients of 3-methyl 4-nitropyridine 1-oxide by an interferometric phase-modulation technique
Authors: Sigelle M. , Hierle R.
Published: February 2003

We present a method for measuring linear electrooptic coefficients involving comparative measurement of interferometric phase-modulation indices at wavelength λ = 6328 Å. The accuracy of the method (8–16%) varies according to the crystalline quality. We have investigated a new nonlinear crystal, 3-methyl 4-nitropyridine 1-oxide. Our single crystals were grown from solution by an evaporation technique. We report some of their physical characteristics and the three electrooptic coefficients: ‖r41‖ = (3.6±0.6)×10−12 m/V; ‖r52‖ = (5.1±0.4)×10−12 m/V; ‖r63‖ = (2.6±0.3)×10−12 m/V. Comparison between second-harmonic generation and electrooptic results is discussed. It is shown that the electronic contribution is preponderant and is about 35% larger than the electrooptic susceptibility. The contribution of intermediate vibrations has therefore a sign opposite to the electronic one and is about four times smaller.
Radiative transfer theory for active remote sensing of a homogenous layer containing spherical scatterers
Authors: Shin R. T. , Kong J. A.
Published: February 2003

The radiative transfer theory with a Rayleigh scattering model is used to study the effect of volume scattering for active microwave remote sensing of low-loss and scattering dominant areas by obtaining backscattering cross sections through iterative and numerical approaches. The iterative approach gives closed form solutions which are valid when the effect of scattering is small. The depolarization of the backscattered power is shown to be a second-order effect. For the general cases, we use a numerical approach to solve the radiative transfer equations. The theoretical results are compared and illustrated for the various cases.
Photoluminescence in the amorphous system SiOx
Authors: Carius R. , Fischer R. , Holzenkämpfer E. , Stuke J.
Published: February 2003

We report on the photoluminescence in the amorphous SiOx alloy system for x = 0–1.44. The films were produced by a glow discharge of suitable mixtures of SiH4 and N2O. We find two luminescence bands, one of which shifts to higher energy with increasing oxygen content in an analogous way as the optical-absorption edge.
Thermoluminescence studies of LiF (TLD-100) in the temperature interval 10–300 K
Authors: Cooke D. Wayne , Rhodes Joanne F.
Published: February 2003

LiF (TLD-100) has been investigated by thermoluminescence (TL) techniques in the temperature interval 10–300 K. Emission spectra data, in conjunction with thermal annealing, photobleaching, and optical repopulation studies, support the model previously proposed by Cooke to explain the TL mechanism in TLD-100 over the temperature range of 90–500 K. By extending the studies to 10 K, six new glow peaks have been observed; maxima occur at 20, 44, 60, 66, 84, and 124 K. The latter peak represents a shoulder on the intense glow peak occurring near 138 K (previously reported) and is attributed to the thermal release of trapped electrons. The remaining peaks are associated with the thermal detrapping of shallow trapped holes which produce 400-nm band emission. By incorporating the existence of shallow trapped holes into the existing model we present a band-gap model which depicts the TL mechanism in TLD-100 valid in the temperature interval 10–500 K.
Ejection of atoms by laser produced optical breakdown plasma
Authors: Wang M. R. , Meng H. C.
Published: February 2003

High-power CO2 laser radiation has been used to study the optical breakdown plasma on various solid targets (NaCl, KBr, ZnSe, and Ge). The breakdown threshold for irreversible changes of the optical characteristics was determined as well as the evaporation threshold of Na atoms from NaCl samples by CO2 laser irradiation; the latter value was about 2.8×107 W/cm2. The time profiles of the ejected Na atoms and the propagation of the atoms in front of the sample was measured with the laser fluorescence method.
The theoretical treatment of range distributions of energetic light ions injected into a semi-infinite random target
Authors: Fedder Steen , Littmark Uffe
Published: February 2003

A method for obtaining range distribution for ion beams bombarding semi-infinite random solids is presented. Calculations are performed for light ions injected into a heavy target (Z≳20). Examples of range distributions for proton projectiles are given together with those obtained from the usual type of calculation where an infinite target is assumed. Pronounced deviations are observed, especially at low projectile energies, where reflected particles penetrating back into the ’’real’’ target cause false particle deposition. At high energies (Lindhard energy parameter ε≳10) these deviations diasappear.
The role of plasma diffusion in heat dissipation during laser annealing
Authors: Jastrzebski L. , Bell A. E. , Wu C. P. , Zanzucchi P. J.
Published: February 2003

The role of the plasma contribution to the heat dissipation during laser annealing of monocrystalline silicon was investigated. The experiments were performed with a Q-switched ruby laser with a pulse length of 25–30 nsec. It was found that for samples with larger values for the minority carrier diffusion length, the threshold energy for annealing was increased and the depth of melting was reduced. The experimental results were compared with a thermal model which takes into account the modification of the distribution of laser energy coupled to the lattice due to the diffusion of the minority carriers which occurs prior to recombination. It is concluded that, due to the significant reduction of the minority carrier diffusion length which occurs under the exteremely high generation rates achieved during laser annealing, the plasma diffusion does not dominate the thermal behavior. However, the effects of plasma diffusion can be observed experimentally and they should not be neglected in a completed description of the laser annealing process.
Induced molecular transport due to surface acoustic waves
Authors: Terry Paul , Strandberg M. W. P.
Published: February 2003

An investigation into the possiblity of inducing a net transport of molecules via their interaction with a propagating surface acoustic wave is reported here. A theory is presented predicting such a transport and giving a formula for the pumping rate of a device consisting of two evacuated chambers connected by a channel of rectangular cross section containing a surface on which a surface acoustic wave is propagating. This formula gives the parametric dependence of the pumping rate on the wavelength, amplitude and velocity of the surface acoustic wave, and the mean molecular velocity of the gas. The results of an experimental investigation are also given. The experiment, conducted with air at approximately 3 μ and a surface acoustic wave on a lithium niobate substrate, confirms the existence of transport and gives a pumping rate which compares favorably with the theoretical prediction. Possible applications of this effect include its use in vacuum technology and studies of surfaces and surface interactions.
Tunneling solar cell under concentrated light illumination
Authors: Myszkowski A. , Sansores L. E. , Tagüeña-Martínez J.
Published: February 2003

The behavior of ITO-SiOx-pSi tunneling solar cell (MIS type) under concentrated light illumination is analyzed theoretically. Conversion efficiency as high as 22.7% is predicted at 75×AM1 illumination. At still higher light concentration the efficiency drops mainly owing to the resistance of the SiOx layer. The numberical calculations show the important role of the interface states in the tunneling process, electrical charge storage, and carrier recombination. Large current flowing through the diode can induce significant quasi-Fermi level drop across the insulator layer and electric charge storage in the depletion region. The operation of the diode cannot be explained by the standard MIS theory of low current densities. Therefore a more general treatment is presented here.
Thermal stability of titanium nitride for shallow junction solar cell contacts
Authors: Cheung N. W. , von Seefeld H. , Nicolet M-A. , Ho F. , Iles P.
Published: February 2003

To demonstrate the thermal stability of titanium nitride as a high-temperature diffusion barrier, the TiN-Ti-Ag metallization scheme has been tested on shallow-junction (∼2000 Å) Si solar cells. Electrical measurements on reference samples with the Ti-Ag metallization scheme show serious degradation after a 600 °C, 10-min annealing. With the TiN-Ti-Ag scheme, no degradation of cell performance is observed after the same heat treatment if the TiN layer is ≳1700 Å. The glass encapsulation of cells by electrostatic bonding requires such a heat treatment.