bluuebunny/crossref_metadata_2025 huggingface dataset:
A study of rf nonlinearities in nickel
Authors: Bailey G. C. , Ehrlich A. C.
Published: February 2003

A new and very sensitive method (1 part in 1019) for studying nonlinear properties of metallic systems under the influence of radio-frequency fields is described. The method is applied to a study of the intermodulation generation at 150 MHz in nickel as a function of a dc field and as a function of the power of the two simultaneously applied rf fields at 146 and 148 MHz. As the dc field is increased for a given applied rf power, the intermodulation signal shows a number of linear regions of decrease on a semilogarithmic graph. Different results are obtained which depend on the relative orientations of the dc and rf magnetic fields. The power of the intermodulation signal shows a cubic or quadratic dependence on the power of the applied rf fields for low or high values of the dc field, respectively. These results are discussed in terms of the interaction of the rf field with the domain walls using a recent model of an electroplated nickel domain structure proposed by others.
Measurement of the chromium concentration in semi-insulating GaAs using optical absorption
Authors: Martin G. M. , Verheijke M. L. , Jansen J.A.J. , Poiblaud G.
Published: February 2003

Chromium has been observed to be responsible for a band of absorption in semi-insulating GaAs. The corresponding absorption coefficient has been carefully calibrated using three different chemical analysis methods. It is shown that the spatial distributions of Cr in semi-insulating GaAs ingots can be obtained very easily using optical absorption measurements and that the segregation coefficient of Cr in GaAs is equal to 8.9×10−4. The nature of the optical transitions due to the presence of Cr is discussed in detail and it is shown that they occur mainly on the Cr3+ in semi-insulating material.
Infrared photoconductivity of shallow impurities in GaP
Authors: Scott Walter
Published: February 2003

The extrinsic photoconductivity of GaP doped with the donors S, Se, Te, or Si and with the acceptors C or Zn has been measured at liquid-helium temperatures in the 400–3000-cm−1 region of the infrared. The ionization energy of these impurities was determined to be 103.5, 102, 90, and 78 meV, respectively, for the donors and 49 and 71 meV, respectively, for the acceptors. Dips in the spectral response of the donors are interpreted as primarily due to electron capture from the conduction band to excited states of the donor atoms together with emission of LA(X) and LO(Γ) phonons. Excited states are observed in the photoconductive spectrum to which transitions from the ground state are forbidden in optical absorption. The spectral response of the acceptors show a prominent oscillatory response due to interaction with LO(Γ) phonons and to capture into the acceptor ground state. Smaller dips due to hole capture from the valence band to excited states are also observed in the p-type crystals, but the excited states responsible have not all been identified in the acceptor spectra.
Dynamic quenching of photocapacitance in CdS : Cu evaporated thin films
Authors: Suda Toshikazu , Kurita Shoichi
Published: February 2003

The effect of the primary light intensity (corresponding to the fundamental absorption edge) on the infrared quenching of photocapacitance (PHCAP IR quenching) in CdS : Cu evaporated films has been studied. Two methods, viz., the two-beam and three-beam methods, for PHCAP IR quenching on detecting deep Cu levels are developed. It has been found that PHCAP IR quenching depends on the primary light intensity, that is, the rates for capturing holes into Cu deep acceptor levels [Cu+ levels and (Cu+Cu+) levels] vary as the primary light intensity changes. The experimental results are consistent with the calculations based on the three-state model of Cu quantitatively. The photoionization cross sections and thermal emission rates of holes were also measured.
Compositionally modulated sputtered InSb/GaSb superlattices: Crystal growth and interlayer diffusion
Authors: Eltoukhy A. H. , Greene J. E.
Published: February 2003

Compositionally modulated single-crystal InSb/GaSb superlattice structures have been grown by multitarget sputtering in order to investigate the effects of film growth parameters on the defect structure, abruptness, and coherence of sputtered heterojunctions. The layer thicknesses studied ranged from 12 to 70 Å. The polycrystalline–to–single-crystal ’’transition temperature’’ Tc was found to decrease with decreasing average film-substrate lattice mismatch and modulation period, Λ. The Λ-dependence resulted from a decrease in the coherence between layers and the associated increased amount of plastically accommodated strain which occurred with increasing layer thickness. Increasing the film growth temperature TS and decreasing the period of the composition modulation also resulted in a decrease in the density of microtwins and low-angle dislocation boundaries which were observed in all films. Single and multiple {111} twins were identified. For a given set of growth conditions on cleaved BaF2 and NaCl substrates, a significant decrease in Tc and structural defect densities could be achieved by coating the substrates with thin (<300Å) single-crystal InSb layers which were deposited and annealed in situ immediately prior to superlattice film growth. Variations in TS between 150 and 320 °C had no effect on either the amplitude of composition modulation in deposited films or on the minimum layer thickness Λmin obtainable from a given set of sputtering conditions. Λmin was, however, found to be dependent on the sputtering pressure and was limited by ion-bombardment-enhanced diffusion during film growth. A model is discussed for determining bombardment-enhanced diffusion coefficients D* as a function of growth conditions using measured x-ray superlattice diffraction intensities. Values of D* obtained in this way were several orders of magnitude larger than thermal diffusion coefficients found from postannealing experiments.
Analysis of the high-field domain dynamics in a planar Gunn diode by using a stroboscopic SEM
Authors: Masuda Masamitsu , Ogura Takeshi , Koyama Jiro , Fujioka Hiromu , Hosokawa Teruo , Ura Katsumi
Published: February 2003

An analysis has been made for the high-field domain dynamics in a planar Gunn diode, based on stroboscopic observations by a scanning electron microscope. The 1-GHz pulsed electron beam was synchronized with the microwave-triggered oscillating diode. The movement of the domain could be clearly observed. The domain dynamics is discussed in detail, taking the time fluctuation in microwave triggering into account. The experimental results are also supported by a theoretical analysis.
Reply to ’Comment on ’’Spinning magnetic fields’’ ’
Authors: Djurić Jovan
Published: February 2003

The comment of Viviani and Viviani concerning the old riddle of unipolar induction and the M (moving) and N (nonmoving) hypotheses contains a contradiction.
Observation of thermal carrier generation in buried channel charge coupled devices
Authors: Mayer G. J.
Published: February 2003

The thermal carrier generation in a buried channel charge coupled device has been observed experimentally. The generation rate decreases dramatically as the potential well fills, compared to the same characteristic in a surface channel charge coupled device.
The effect of oxidation on the diffusion of phosphorus in silicon
Authors: Francis R. , Dobson P. S.
Published: February 2003

The diffusion of phosphorus from a thick epitaxial layer into a silicon substrate has been investigated using the spreading-resistance technique. By comparing the diffusion profile under a free oxidized surface with the profile under a masked surface, it has been shown that surface oxidation enhances diffusion at low temperatures and retards diffusion at high temperatures. The conditions which favor enhanced diffusion are those under which stacking faults grow; retarded diffusion is associated with stacking-fault shrinkage. Enhanced diffusion is due to the oxide injecting excess interstitials into the substrate; retarded diffusion is caused by vacancy injection. It is concluded that phosphorus diffuses by the interstitialcy mechanism and that the criterion for interstitial or vacancy injection is the relative value of the anion and cation fluxes across the oxide-silicon interface.
Silicide formation with bilayers of Pd-Pt, Pd-Ni, and Pt-Ni
Authors: Finstad T. G. , Nicolet M-A.
Published: February 2003

Evaporated two-layered thin films of Pd-Ni, Pt-Ni, and Pt-Pd on single-crystal Si have been vacuum annealed in the temperature range 200–900 °C. The sequence of films as well as substrate orientation have been varied. The silicide formation has been studied by MeV He+ backscattering spectrometry and glancing angle x-ray diffraction. The silicide layers are highly inhomogeneous in the elemental depth distribution for annealing below 600 °C. Above 700 °C, the distributions become homogeneous. The silicide-substrate interface shows varying sharpness depending upon substrate orientation and evaporation sequence. We suggest the existence of ternary monosilicides of the type Pt1−xPdxSi, Pt1−xNixSi, and Pd1−xNixSi. The Pt1−xPdxSi ternary silicide is stable up to 900 °C; the others are not.
Fine carbon particle formation by carbon-vapor condensation
Authors: Kappler Patrick , Ehrburger Pierre , Lahaye Jacques , Donnet Jean-Baptiste
Published: February 2003

Carbon vapor obtained by vaporization of graphite is diluted into argon. Its subsequent condensation into solid particles is studied. The particle diameter is determined as a function of argon and carbon partial pressures and of the distance to the carbon source. A mechanism involving irreversible associations of colliding particles is proposed.
New model of conduction mechanism in semi-insulating GaAs
Authors: Robert J. L. , Pistoulet B. , Raymond A. , Dusseau J. M. , Martin G. M.
Published: February 2003

Variations versus temperature of the electrical properties (conductivity, Hall and drift mobilities) in semi-insulating GaAs are explained by a model which accounts for the spatial fluctuation of impurity densities. A discussion of this model is also presented.
Galvanomagnetic and thermopower studies in heavily compensated zinc selenide crystals
Authors: Sethi B. R. , Mathur P. C. , Woods J.
Published: February 2003

The Hall coefficient, dc conductivity, and thermopower have been measured in three single crystals of zinc selenide heavily doped with indium to various degrees. It has been found that the excessive doping with indium leads to an increase of compensation with the increase of doping. The galvanomagnetic as well as thermopower measurements suggest impurity-band conduction in the entire temperature region investigated (77–300 °K) in this material.
Diffusion and the power spectral density of velocity fluctuations for electrons in InP by Monte Carlo methods
Authors: Hill G. , Robson P. N. , Fawcett W.
Published: February 2003

The low-frequency parallel and transverse diffusion coefficients for electrons in InP are calculated using Monte Carlo methods for lattice temperatures of 200, 300, and 500 K. The sensitivity of the computed values to the duration of the flight sampling time is investigated, and this is shown to be a consequence of the frequency dependence of the diffusion coefficient. To test this hypothesis the variation of the parallel diffusion coefficient with both frequency and field at 300 K is determined. For fields above threshold the parallel diffusion coefficient first rises from its low-frequency value to a maximum and thereafter decreases with increasing frequency; for fields substantially below threshold a slow monotonic decrease is observed.
Electrical 1/f noise in insulating polymers
Authors: Pender L. F. , Wintle H. J.
Published: February 2003

Electrical noise measurments have been made on thin films of PS, PE, and PET, over the frequency range 10−4–1 Hz, the temperature range 20–80 °C, and under applied fields up to destructive breakdown. The noise power is found to be less than the measurable limit of 10−29 A2/Hz until near-breakdown fields are applied, at which time a rapid increase in noise is observed with noise-power spectra varying with frequency as 1/fα, with 1.3<α<1.7, and proportional to the square of the steady current. Very similar characteristics were observed in all three polymers. We give a tentative explanation for this high-field phenomenon in terms of the activation of sensitive spots, thermal runaway, and subsequent annealing.
Charge transfer in metal-polymer contacts and the validity of ’’contact charge spectroscopy’’
Authors: Cottrell G. A. , Lowell J. , Rose-Innes A. C.
Published: February 2003

A number of recent papers have reported measurements which seem to show that charge transferred to polymers by successive contacts to different metals is additive, each metal transferring an amount of charge independent of that deposited by previous metals. These results have been interpreted as showing that a metal may only transfer charge to a narrow range of polymer states close to the metal’s Fermi level, and it has been suggested that this effect may be used to study the energy spectrum of electron states in polymers (’’contact charge spectroscopy’’). We show that if the sample geometry is chosen to define more precisely the region of true contact, charging by a succession of metals is not additive; the charge depends only on the most recent contacting metal. This throws doubt on the hypothesis of charge transfer to a narrow range of states and on the technique of contact charge spectroscopy.
High-temperature behavior of ZnO-based ceramic varistors
Authors: Philipp H. R. , Levinson Lionel M.
Published: February 2003

Current-voltage data for metal oxide varistors are presented in the temperature range 100–1300 °C and for current densities as high as 103 A/cm2. The current-voltage characteristic can be crudely represented at all temperatures by a breakdown line I=CVα where α≳30 (and is somewhat voltage dependent) and a temperature-dependent Ohmic leakage conduction, α=1, which is smoothly joined to the breakdown characteristic by a transition region (1<α<30) called the prebreakdown region. The Ohmic conductance is associated with a thermal excitation process over grain-boundary barriers and can be resolved into three distinct thermally activated regions which are correlated with similar features found in conductivity data for pure sintered ZnO. Low-field capacitance data on varistors show that all or part of these barriers can be attributed to depletion layers in the ZnO grains. Additional studies at very high average power levels show that the varistor characteristic can be degraded when the temperature is allowed to increase unduly due to self-heating. This degradation effects only the Ohmic and prebreakdown regions; the breakdown characteristic is unaltered. The varistor can be restored to its initial state by annealing.
Determination of surface-state parameters from transfer-loss measurements in CCD’s
Authors: Kriegler R. J. , Devenyi T. F. , Chik K. D. , Shappir J.
Published: February 2003

A novel experimental method is described that allows the determination of surface-state capture cross section for minority carriers and the calculation of surface-state densities from transfer-loss measurements in surface channel CCD’s. Using two-level polysilicon two-phase n-channel CCD’s, σn(E) was found to vary between about 5×10−17 and 2×10−16 cm2, and Nss(E) between 1.7×1011 and 9×109 cm−2 eV−1 in an energy range of 0.05 to 0.42 eV below the conduction-band edge.
Investigation of the transient ionizing regime of laser-produced plasma
Authors: Zigler A. , Zmora H. , Loebenstein H. M. , Schwob J. L.
Published: February 2003

The spatial and temporal behavior of the x-ray emission from laser-produced aluminum plasma was deduced from space-resolved x-ray lines and satellite spectra and from a comparison between spectra observed from both sides of thin (1–25-μm) foils. The Li-, He-, and H-like ion species were found to have different spatial and temporal behaviors. The evolution of the plasma from the ionizing regime to steady state is also followed. The meaning of electron temperature values deduced from various spectral line ratios is discussed.
An integral equation method for the analysis of magnetic deflection yokes
Authors: Fye Donald M.
Published: February 2003

An integral equation method is developed for the computer modeling of the magnetic fields produced by color television deflection yokes. Saddle or toroidal yokes with either radial or nonradial winding distributions can be analyzed using this new technique. The integral equation method is shown to yield magnetic field calculations that are at least as accurate as those produced by conventional finite-difference analysis. In most cases computer algorithms using the integral equation approach have been found to be more computationally efficient than existing finite-difference programs.
Recrystallization of implanted amorphous silicon layers. I. Electrical properties of silicon implanted with BF+2 or Si++B+
Authors: Tsai M. Y. , Streetman B. G.
Published: February 2003

Electrical properties of recrystallized amorphous silicon layers, formed by BF+2 implants or Si++B+ implants, have been studied by differential resistivity and Hall-effect measurements. Electrical carrier distribution profiles show that boron atoms inside the amorphized Si layers can be fully activated during recrystallization at 550 °C. The mobility is also recovered. However, the tail of the B distribution, located inside a damaged region near the original amorphous-crystalline interface, remains inactive. This inactive tail has been observed for all samples implanted with BF+2. Only in a thicker amorphous layer, formed for example by Si+ predamage implants, can the entire B profile be activated. The etch rate of amorphous silicon in HF and the effect of fluorine on the recrystallization rate are also reported.
Recrystallization of implanted amorphous silicon layers. II. Migration of fluorine in BF+2-implanted silicon
Authors: Tsai M. Y. , Day D. S. , Streetman B. G. , Williams P. , Evans C. A.
Published: February 2003

Fluorine distribution profiles for silicon implanted with BF+2 have been measured by SIMS as a function of anneal temperature and time. Anomalous migration of fluorine is observed in samples having amorphized layers after implantation. Outdiffusion of fluorine occurs during recrystallization of the amorphous layer, and fluorine collects in regions of residual damage during annealing. This gettering of fluorine by defects illustrates the residual damage below the amorphized layer in samples implanted at room temperature is more difficult to anneal out than that in samples implanted at lower temperture (∼−110 °C).
Calculated properties of vertical arcs stabilized by natural convection
Authors: Lowke J. J.
Published: February 2003

The equations of energy, continuity, and momentum are solved to give axial and radial values of temperature, pressure, and axial and radial velocity for vertical arcs stabilized by natural convection. It is assumed that the electric field is purely axial and magnetic forces are neglected. For a free-burning arc of 10 A in air, calculated temperature and velocity profiles are in good agreement with published experimental results. For an arc in an enclosed vertical tube of mercury vapor, results of central velocities as a function of axial position for a 2.9-A arc are in good agreement with the experimental results of Kenty. Comparisons are made of the differing properties predicted for free-burning arcs of 10 A in air, sulfur hexafluoride, and hydrogen. Removal of the maxima in the thermal conductivity has a negligible effect on the degree of predicted arc constriction in SF6. Convective flow in all calculations is assumed to be laminar. The influence of radial pressure variations is found to be almost negligible.
Experimental study of precipitation in an ion-implanted metal: Sb in Al
Authors: Kant R. A. , Myers S. M. , Picraux S. T.
Published: February 2003

The formation and evolution of AlSb precipitates in Sb-implanted Al has been investigated as a function of temperature, flux, and fluence. Implant temperatures of 23–300 °C, fluxes of 6×1011 to 1.3×1013 Sb cm−2 sec−1, and fluences of 5×1015 to 2×1017 Sb cm−2 were investigated, and transmission electron microscopy was used to detect the precipitates and to determine their size distributions. The AlSb precipitate mean size becomes larger and the number density decreases with increasing Sb implantation temperature, with increasing fluence, and with decreasing flux. The temperature and flux dependences of the evolution are large for 5×1015 Sb cm−2 added to initially pure Al, and are much weaker at higher fluences where 1.5×1015 Sb cm−2 has been added to a preexisting precipitate distribution. This indicates that flux and temperature affect the size distribution most strongly during nucleation and/or early growth. Ion damage has been demonstrated to be a significant factor in the precipitate evolution through Ar and Al bombardment of preexisting precipitates. At 300 °C self-ion bombardment leads to ripening, whereas the precipitate size distribution is stable in the absence of implantation. At room temperature, Ar irradiation causes the AlSb diffraction pattern to disappear at ∼1 displacement per atom (dpa) independent of precipitate size, suggesting that here destruction of precipitates occurs due to disordering of the AlSb lattice. The results are discussed in terms of thermal and irradiation-induced processes.
Damage-dependent electrical activation of ion-implanted silicon. I. Experiments on phosphorus implants
Authors: Miyao M. , Yoshihiro N. , Tokuyama T. , Mitsuishi T.
Published: February 2003

The electrical activation mechanism of phosphorus ions implanted into a silicon substrate is studied during low-temperature (?550 °C) annealing. Apparently anomalous behavior where the electrically active fraction versus dose curve shows a peak in a limited dose range is analyzed by measuring the distribution profiles of damage and carrier concentration. Carrier generation was found to be strongly influenced by the extent of damage in the layer. Phosphorus atoms in layers with less than 20% damage were not electrically activated. However, in layers with more than 20% damage, electrical activation abruptly increased with the change of damage. This correlation existed at each depth in the substrate for all samples with various doses. The anomalous dose dependence of the electrically active fraction was recognized to be an integral result of the phenomenon. Analysis of the damage formation showed that overlapping of amorphous clusters produced in each ion trajectory is essential for the electrical activation of implanted impurities. This is related to the carrier compensation center which might be formed after recovery of the amorhpous clusters.
Accounting for resistive hysteresis in calibrating Manganin stress gauges undergoing dynamic loading
Authors: Steinberg D. J. , Banner D. L.
Published: February 2003

A technique is described for calibrating the effect of resistive hysteresis on the dynamic piezoresistive coefficient in Manganin stress gauges.
A fluid-flow-temperature model for the casting of amorphous metal ribbon by melt extraction
Authors: Anthony T. R. , Cline H. E.
Published: February 2003

Equations describing the velocity, temperature, and vorticity distributions in the melt of the melt extraction process are derived. It is shown that the melt extraction process can only produce ribbon with a thickness greater than that of the viscous shear layer in the melt. From the minimum quench rate required to produce amorphous metal, a maximum amorphous ribbon thickness and a minimum roller velocity are found. A maximum roller velocity is determined from a balance of opposing centrifugal forces and melt pressure and adhesion forces exerted on the ribbon.
Steering of magnetostatic bulk waves in a dielectric layered structure
Authors: Bajpai S. N.
Published: February 2003

A theoretical investigation of magnetic steering of magnetostatic bulk waves in a YIG film has been presented. The dependence of steering angle on various parameters, e.g., wave frequency, biasing field, and the angle between the direction of phase propagation and biasing field, has been numerically investigated. It is seen that the steering angle can be controlled by a suitable choice of parameters.
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o calculations of the deformation of polyethylene
Authors: Crist B. , Ratner M. A. , Brower A. L. , Sabin J. R.
Published: February 2003

A b initio H-F SCF quantum-mechanical calculations have been done to evaluate the energy of covalent bond deformation of a –CH2CH2– ethylene repeat unit at strains up to ε=0.6. The computational scheme involves subtracting energies of axially strained normal paraffins (n-C3H8, n-C5H12, and n-C7H16) differing in length by one ethylene unit. At small strains it is found that the deformation is contributed to equally by C–C bond stretch and by CCC bond angle opening. At higher strains the majority of the deformation is accomplished by C–C stretch. The calculated elastic modulus is 405 GPa and the tensile strength of the polymer in the chain direction is 66 GPa. While both of these values are higher than previous estimates, it is believed that these quantities are the most reliable which have been calculated.
Formation, decomposition, and electrical transport properties of amorphous Hf-Ni and Hf-Co alloys
Authors: Buschow K. H. J. , Beekmans N. M.
Published: February 2003

Amorphous Hf1−xNix and Hf1−xCox alloys in the concentration range 0.2⩽x⩽0.9 were prepared by melt spinning. The crystallization behavior of these alloys was studied by means of differential scanning calorimetry and x-ray diffraction. At least two new compounds in the Hf-Ni system were observed to be formed upon crystallization of the amorphous alloys. The electrical resistivity (ρ) in the amorphous alloys and in crystalline HfNi5 was studied in the range from 4.2 to 300 K. Negative temperature dependences of ρ were observed in several of the amorphous alloys, extending from x=0.25 to x=0.65 in Hf1−xNix. The thermal stability of the amorphous alloys is discussed in terms of a diffusion mechanism. The extended Ziman theory of liquid metals was used in the interpretation of the temperature dependence of the resistivity.
Electron trapping in SiO2 at 295 and 77 °K
Authors: Young D. R. , Irene E. A. , DiMaria D. J. , De Keersmaecker R. F. , Massoud H. Z.
Published: February 2003

The electron trapping behavior of SiO2 has been measured as a function of thickness at 295 and 77 °K. The devices used were metal-oxide-semiconductor devices with the SiO2 grown thermally. The results indicate bulk traps are dominant at 295 °K and traps associated with the Si-SiO2 interface are dominant at 77 °K. The effect of processing conditions was also studied and the optimum conditions are different for the two temperatures used for the measurements. These observations have been verified using a photo I-V technique. The generation of donor states in the SiO2 near the Si-SiO2 interface was observed as a result of the electron current through the SiO2.
Deep-state-controlled minority-carrier lifetime in n-type gallium phosphide
Authors: Hamilton B. , Peaker A. R. , Wight D. R.
Published: February 2003

Details of a method for the characterization of deep levels with large capture cross sections for minority carriers are presented. This technique has been used to investigate centers in gallium phosphide. Two defects at EV+0.75 eV and EV+0.95 eV are described in detail. Evidence is presented that shows that the shallower of these defects can control the minority-carrier lifetime in n-type gallium phosphide and in fact is the dominant recombination center in most epitaxial layers of this material. The technique uses capacitance as a measure of the charge state of the deep levels in the depletion region of a Schottky barrier. This charge state is perturbed by the capture and subsequent thermal emission of minority carriers. The carriers are generated by irradiation of the semiconductor with low-intensity light at a wavelength near the absorption edge. Minority carriers generated in the neutral material within about a diffusion length of the barrier region are extracted by the depletion field. Majority carriers are excluded by the field and consequently the current through the barrier is due predominantly to minority carriers. These are captured by the defects, the fastest capture being into the levels with the largest capture cross sections. As a result, the technique can in many cases be used selectively to detect the most important recombination centers in a semiconductor and to determine their capture cross sections, concentrations, and energy depths.
Recovery curve for threshold-switching NbO2
Authors: Vezzoli Gary C.
Published: February 2003

Threshold switching has been observed and studied in thin films of NbOx (x?2) in the sandwich configuration and in a single-crystal device having both a gap and sandwich configuration. The recovery curve has been determined by measuring the reswitching voltage after a specific zero-voltage interruption time. Data indicate a maximum allowable interruption time of about 200 ns without a switch-off transition. This is interpreted as the distribution trapped-carrier lifetime for polycrystalline NbO2.
Laser-emission cross sections of MeNdP4O12 (Me=Li, Na, K) crystals
Authors: Nakano Jun’ichi , Kubodera Ken’ichi , Yamada Tomoaki , Miyazawa Shintaro
Published: February 2003

Emission cross sections of a Nd stoichiometric laser crystal LiNdP4O12 at 1.048 μm were measured by a direct absorption method and the conventional spectroscopic method. The largest effective-emission cross section was determined to be σbeff= (1.7±0.2) ×10−19 cm2 by these two methods. Emission cross sections of NaNdP4O12, KNdP4O12 and LiNd0.1Ln0.9P4O12 (Ln=Gd, La) were also determined by the conventional spectroscopic method. The radiative lifetime of LiNdP4O12 was calculated from the fluorescence spectra and the quantum efficiency of LiNdP4O12 was found to be 0.34.
Surface electrical breakdown of tin oxide coated glass
Authors: Jolly D. C. , Chu S. T.
Published: February 2003

A novel form of surface electrical breakdown is described in which the breakdown field strength can be as low as 200 V/cm at atmospheric pressure. The surface discharge is a high-pressure arc supplied with current through a resistive surface layer. Using a theoretically derived expression for the volt-ampere characteristic of the arc, lower and upper bounds for the breakdown field can be calculated. The measured value lies between these bounds.
A nanosecond surface discharge study in low pressures
Authors: Murooka Y. , Koyama S.
Published: February 2003

The developing velocities of the positive and negative corona streamers on insulating plates have been measured by using the dust figure technique at low pressure in air. By applying nanosecond time pulses from 10- to 50-nsec duration to a needle point where the insulating plate is sandwiched in between the needle and plate electrodes, the diameters of the recorded dincharge pattern against the pulse duration in a pressure range of 150 to 760 Torr were obtained. The maximum velocities of the developing corona streamers which were measured at a voltage of 13.0 kV were 3.0×108 cm/sec in the positive case and 2.5×108 cm/sec in the negative case for a pressure of 150 Torr. Moreover, when a time pulse of 10 nsec was applied to the needle point at a pressure of less than 250 Torr, the velocity of the positive streamer seemed to reach a limiting value for a given voltage, while the negative increased proportionately to the inverse of the pressure. The resulting polarity effect suggests that when the nanosecond pulse voltage is applied, the field distortion due to the accumulation of the positive ions produced by electron-collision ionization is one of the most important phenomena for the positive streamer developing at low pressure.
The electron drag on mobile dislocations in copper and aluminum at low temperatures—Strain rate, temperature, and field dependence
Authors: Galligan J. M. , Pang C. S.
Published: February 2003

Experimental results are presented which show how the electron drag on mobile dislocations varies with temperature, applied strain rate, and magnetic field. In both copper and aluminum the same functional dependence of the change in stress with magnetic field is observed, that is, the change in stress varies with the square of the field, and is independent of temperature and applied strain rate, for a given change in field. These results are compared with various models of electron dislocation drag, for the case where the dislocations move as underdamped oscillators. The observations are qualitatively consistent with the dislocations moving as underdamped oscillators, for the temperature range studied.
Dynamic deformation of polycrystalline alumina
Authors: Munson D. E. , Lawrence R. J.
Published: February 2003

Using one-dimensional strain conditions, the dynamic stress-wave response of polycrystalline Al2O3 was measured with interferometry in both stress-wave loading and unloading to about 16 GPa and with slanted resistor gauges in loading to about 50 GPa. The stress-wave loading and unloading measurements were of high resolution and showed a 9.1-GPa elastic precursor wave (velocity 10.9 km/s) followed by a slower dispersive permanent deformation wave. Unloading was elastic in the stress range of these experiments. Both loading and unloading wave propagation were modeled well with a Maxwellian elastic-stress-relaxing model with a yield stress of 5.8 GPa and a relaxation time of 70 ns. The rate-dependent model correctly predicts both the dispersion of the permanent deformation wave and the unloading-wave behavior. The bulk pressure-volume behavior of alumina is given by the shock-velocity–particle-velocity relationship of Us=8.14 +1.28up (km/s). Thermodynamic corrections to the dynamic bulk response yielded isothermal pressure-volume results which agreed well with direct hydrostatic determinations on polycrystalline Al2O3 and with results deduced from ultrasonic determinations on Lucalox. Permanent deformation of Al2O3 from a micromechanical standpoint appeared to be compatible with a model involving general microcracking throughout the volume of the material. This model is supported by the lack of an appreciable spall strength. When the yield process is ascribed to the onset of microfracture, which depends upon the initial flaw size and distribution, the earlier results on single crystals are phenomenologically related to the stress-wave behavior observed during this study on polycrystalline alumina.
Hashin-Shtrikman bounds on the effective elastic moduli of polycrystals with orthorhombic symmetry
Authors: Watt J. Peter
Published: February 2003

Bounds on the effective elastic moduli of randomly oriented aggregates of orthorhombic crystals have been derived using the variational principles of Hashin and Shtrikman. The bounds are considerably narrower than the widely used Voigt bound and Reuss bound. In many instances, the separation between the new bounds is comparable to, or less than, the uncertainty introduced by experimental errors in the single-crystal elastic stiffnesses. The Voigt-Reuss-Hill average lies within the Hashin-Shtrikman bounds. several percent.
Oscillatory-to-nonoscillatory transition due to external noise in a parametric oscillator
Authors: Kabashima S. , Kogure S. , Kawakubo T. , Okada T.
Published: February 2003

A degenerate parametric oscillator which is driven by a random current additionally applied to a sinusoidal pumping current is found to exhibit a new type of oscillatory-to-nonoscillatory transition. This noise-induced phase transition has a different kind of critical behavior from that observed in usual phase transitions, that is, near the threshold the variance of the fluctuating output current remains constant, however, the critical slowing-down does occur. A stochastic equation for the parametric oscillation which includes a random force multiplied by the amplitude itself is derived and the experimental results are fully accounted for in terms of that equation.
XPS observation of Fe1−xO at temperatures between 25 and 800 °C
Authors: Oku Masaoki , Hirokawa Kichinosuke
Published: February 2003

Variations of the XPS spectra of Fe1−xO crystal and iron metal oxidized in air were studied when the samples were heated in a vacuum. The structural variations observed by XPS can be explained by the phase diagram of the iron-oxygen system. The intensity ratio of O 1s to Fe 2p3/2 for Fe1−xO at 800 °C in thermal equilibrium was smaller than that of the sample quenched from 800 °C to room temperature. This indicates that quenching the sample changes the surface structure. FWHM (full width at half-maximum) of 2.2 eV of O 1s for Fe1−xO was larger than that of 1.7 eV for α-Fe2O3. The broader FWHM is due to the large value of x and clustering of the cation vacancies in Fe1−xO. The binding energies and spectral profiles of Fe 3s and Fe 2p1/2,3/2 for Fe1−xO coincided with the spectra for Fe2SiO4 or FeTiO3 having only divalent iron ions.
Contact reaction between Si and Pd-W alloy films
Authors: Olowolafe J. O. , Tu K. N. , Angilello J.
Published: February 2003

Contact reactions in the temperature range 250–650 °C between (100) Si and Pd-W binary alloy films of composition Pd80W20 and Pd30W70 have been studied by a combination of ion backscattering, x-ray diffraction, and current-voltage measurement of Schottky barrier height. For the Pd-rich alloy, the reaction around 400 °C produced the silicide Pd2Si by depleting Pd from the alloy and resulted in the formation of a two-layer structure, W/Pd2Si/Si. We have found that the W layer has served effectively as a diffusion barrier for the subsequently deposited Al, indicating that a rectifying contact and its diffusion barrier can be fabricated simultaneously. At higher reaction temperatures, the W layer transforms to WSi2 with some mixture of Pd2Si. The alloying of Pd with W has been found to increase the formation temperature of Pd2Si but decrease that of WSi2. In the Pd80W20 reaction, Pd2Si forms around 400 °C and WSi2 around 500 °C. In the Pd30W70 reaction, Pd2Si forms around 500 °C and WSi2 around 650 °C.
Electric and optical properties of the ’’Cu-red’’ center in ZnSe
Authors: Grimmeiss H. G. , Ovrén C. , Mach R.
Published: February 2003

Emission and capture rates describing the optical and thermal transitions at the ’’Cu-red’’ center in ZnSe have been investigated using a modified photocapacitance technique. By keeping the depletion region of a Schottky diode constant during the measurements of transients highly compensated samples could be used, resulting in larger signals than previously possible. This permitted optical-emission rates for both electrons and holes to be measured with higher accuracy and in a broader temperature region than in previous investigations. The capture cross section of electrons σn was determined in the temperature range 77–200 K. σn increases with decreasing temperature and has a value of 1.4×10−19 cm2 at 77 K.
Electronic energy-band structure of t
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s-polyacetylene: EHCO and MNDO studies
Authors: Young V. , Suck S. H. , Hellmuth E. W.
Published: February 2003

Extended Hückel and MNDO programs developed for molecular systems have been modified without reparametrization to perform crystal orbital calculations. A comparison of the qualitative results of these methods with the extended tight binding results of Grant as applied to the band structure calculation of trans-polyacetylene is presented. It is demonstrated that the ETB, EHCO, and MNDO methods give results which show a similar trend with minor differences in detail. The usefulness of the crystal orbital method for the interpretation of experimental density of state curves of doped and undoped polymers is inferred from this study and previous studies on polyethylene.
An infrared study of phase-III poly(vinylidene fluoride)
Authors: Bachmann M. A. , Gordon W. L. , Koenig J.L. , Lando J. B.
Published: February 2003

Infrared spectra representative of crystalline regions of cast films of phase-III poly(vinylidene fluoride) (PVF2) have been obtained by absorbance subtraction techniques using a FT-IR instrument. The spectra contain more bands than previously reported and are not consistent with current models for the crystal structure. Several possible models and their relationship to the corresponding crystalline spectra of phase II and phase I are discussed.
Eddy currents in a conducting cylinder with a crack
Authors: Spal R. , Kahn A. H.
Published: February 2003

We report calculations for the impedance of a long solenoid which surrounds a cylinder of conducting material containing a radial surface crack of constant depth. The calculation is accomplished by solving for the longitudinal ac magnetic field in the interior of the ’’cracked’’ cylinder in terms of an infinite series of cylindrical Bessel functions. All the coefficients in the series are determined in principle by boundary-condtion requirements and the most significant terms are obtained numerically by truncation of the series. The resulting impedance is calculated for a wide range of values of the ratios of crack depth to radius and radius to skin depth. The results are tabulated in a form useful for nondestructive testing purposes.
Forced convective cooling of optical fibers in high-speed coating
Authors: Paek U. C. , Schroeder C. M.
Published: February 2003

The high-speed coating of optical fibers must consider the possibility of a very hot fiber contacting coating material. In this case, the quality of coating may deteriorate if the fiber temperature is above a certain point. Hence, gas-assisted cooling of fiber was investigated and its effectiveness compared with the self-cooling case. A cylindrical air blower of 2.5 cm diameter and 20 cm length with a slit (0.2 cm×20 cm) along its axis was employed to cool the fiber entering the coating cup. Measured fiber cooling rates are compared to calculated ones and are in good agreement. It is shown that this technique can result in a twofold increase in coating speed without deteriorating the coating material.
Enthalpic retardation times of annealed polystyrene
Authors: O’Reilly J. M.
Published: February 2003

An equation for the retardation time for enthalpy recovery has been tested for polystyrene as a function of heating rate, temperature, and initial displacement. The temperature dependence ϑ and displacement dependence ξ of the retardation time are determined from the data assuming a single relaxation time. The fraction of the temperature dependence of the retardation time due to structure (1−X) and due purely to temperature (X) are calculated and compared with results for other polymers. Some factors which can affect X are discussed.
Ti diffusion in Ti : LiNbO3 planar and channel optical waveguides
Authors: Burns W. K. , Klein P. H. , West E. J. , Plew L. E.
Published: February 2003

Optical mode measurements have been used to determine the anisotropic diffusion coefficient and surface index changes for planar Ti : LiNbO3 waveguides at 0.633 μm. Measured values for the diffusion coefficient at 1000 °C are 𝒟y=9.4×10−13 and 𝒟z=1.4×10−12 cm2/sec. The ratio of the extraordinary to the ordinary surface index change (Δne/Δn0) was found to vary between 1.3 and 1.8, depending on diffusion temperature and Ti film thickness. Ti and Li concentration profiles were measured by secondary-ion mass spectrometry. Additional high concentration peaks, 0.2–0.3 μm wide for both ions, were found superimposed on otherwise well-behaved diffusion profiles. This observation is interpreted to result from a tendency towards Li-Ti-O compound (Li2TiO3 or Li2Ti3O7) formation at the diffusion temperature in a dilute mixture with LiNbO3. Such compound formation has the effect of impeding the Ti diffusion into the LiNbO3 substrate. Electron microprobe measurements were used to measure lateral diffusion from channel waveguides. Under nominally identical conditions, lateral diffusion coefficients varying by as much as a factor of 3 have been observed. The minimum lateral diffusion coefficients observed at 1000 °C were 𝒟y=9.7×10−13 and 𝒟z=1.4×10−12 cm2/sec.
Barrier height of evaporated-manganese contacts to silicon
Authors: Ali M. P. , Tove P. A. , Ibrahim M.
Published: February 2003

By studying the temperature dependence of the current of reverse-biased contacts between evaporated-manganese films and p-type silicon which were pretreated by chemical etching, it was deduced that the hole barrier of the contact is 0.86±0.05 eV. When the Si crystal had undergone some oxidizing treatment in an oxygen atmosphere at moderate temperature before the vacuum deposition of Mn, the barrier height decreased to 0.75 eV. This trend is in accordance with what is expected when the presence of surface states result in a slight potential drop across the oxide.
Electrical activation process of phosphorus atoms with annealing for doped CVD poly-Si
Authors: Hasegawa S. , Kasajima T. , Shimizu T.
Published: February 2003

The electrical activation process of the incorporated P atoms with annealing for CVD poly-Si is investigated using ESR. As a result, it is concluded that the P atoms act first as compensators on ESR centers due to dangling bonds, and conduction electrons are supplied from the remaining P atoms. Furthermore, the following possibilities are suggested: (1) The increase of the conduction electron density with annealing is not due to the increase of the crystalline region, but the increase of the conduction electron density in crystallites due to the decrease of defect density. (2) The mobility in crystallites is determined mainly by P impurity scattering as in crystalline Si.
cw infrared laser annealing of ion-implanted silicon
Authors: Celler G. K. , Poate J. M. , Rozgonyi G. A. , Sheng T. T.
Published: February 2003

Solid phase epitaxial regrowth of ion-implanted Si was obtained with cw infrared radiation of CO2 (10.6 μm) and Nd : YAG lasers. Arsenic-implanted samples were analyzed by optical and electron transmission microscopy and by Rutherford backscattering with channeling. Dislocation-free monocrystalline structures were obtained on substrates which were preheated to 200–400 °C and then scanned with a laser beam of ∼25 W. There was no redistribution of the implanted As and the sample surface was free of any features which might indicate melting. A channeling angular scan showed that the As atoms were located exactly on the lattice sites. However, the relatively high values of sheet resistance suggest the presence of residual point defects.