bluuebunny/crossref_metadata_2025 huggingface dataset:
Cathode Dark-Space Measurements and Deposition Rates of Tantalum in a Sputtering System
Authors: Westwood W. D. , Boynton R.
Published: February 2004

Measurements of the cathode dark-space distance have been made, both visually and electrically, for an argon discharge in a dc diode sputtering system fitted with a tantalum cathode. The values are fitted by Aston's dark-space equation and have been used to calculate the dependence of sputtering rates on discharge conditions. These calculated values are in good agreement with the deposition rates measured for films deposited on glass substrates. The variation of discharge voltage with current does not fit Aston's cathode-fall equation, which must be modified slightly. A change of slope observed in the current-voltage relationship may be due to heating of the system by the discharge. The modified Aston's equation also fitted the current-voltage curve for a platinum cathode and the same change of slope was observed.
GaAs–AlxGa1−xAs Double Heterostructure Lasers—Effect of Doping on Lasing Characteristics of GaAs
Authors: Pinkas E. , Miller B. I. , Hayashi I. , Foy P. W.
Published: February 2004

The GaAs–AlxGa1−xAs double heterostructure (DH) junction laser is shown to be a most suitable structure for studying lasing properties of GaAs as a result of complete optical and carrier confinement. Lasers fabricated from highly uniform DH wafers permitted accurate measurement of thresholds and efficiencies as a function of laser length. Thus the gain and loss for ``bulk'' GaAs at room temperature were determined for the first time without ambiguity. The gain was found to vary with current as g∝Jm, where m ranges from 1.5 to 3 depending on doping. At low excitation the gain is appreciably higher for lasers with heavily compensated active layers than for lasers with lightly doped active layers. The dependence of gain on current agrees qualitatively with the theoretical results of Stern and Hwang. The internal loss of the DH laser agrees approximately with the value which is estimated from passive free-carrier absorption of bulk GaAs.
Interpretation of X-Ray Diffraction Data with Regard to Stacking Faults in Silver-Tin Alloys
Authors: Ruff A. W.
Published: February 2004

Several alternative interpretations of data from fcc silver-tin alloys are discussed in examining the relation between stacking-fault probability and stacking-fault energy. One important aspect concerns the true variation of dislocation density with alloy composition.
Acoustic Attenuation in TeO2
Authors: Uchida Naoya
Published: February 2004

Acoustic absorption coefficients for several principal modes in single crystals of TeO2 of improved quality have been redetermined. The present values are smaller than those obtained earlier and the crystal is found to be useful for acousto-optic devices in the frequency region higher than that considered previously.
Interaction between Dislocation Pile Ups
Authors: Pande C. S. , Pozner M. E. M. , Hazzledine P. M
Published: February 2004

The interaction between two pile ups containing equal number of dislocations in four different configurations is calculated by an approximate analytical method. The calculated lengths of the interacting pile ups are compared with those obtained numerically, and shown to be in good agreement. Both analytical and numerical results show that the interaction between the pile ups is appreciable when the interplanar spacing of the pile up is less than the length of an isolated pile up. The analytical method presented here could prove useful in the study of strain hardening of solids.
Oscillation Modes of Nematic Liquid Crystals
Authors: Conners G. H. , Paxton K. B.
Published: February 2004

A novel self-contained two-dimensional contiuum theory for thin nematic liquid crystal layers has been developed. The theory, which is quasistatic in nature, predicts spatially varying oscillations of the molecular axes in modal striated patterns in response to an ac electric field. An oscillation threshold voltage is derived which increases with increased frequency of excitation. Also, the theory predicts that the spatial frequency of threshold striations increases similarly with increased frequency of excitation. These experimentally observed threshold effects are predicted without the introduction of shear torques, which have been of importance in earlier one-dimensional treatments of the problem, including hydrodynamic effects. The present theory includes torques arising from dielectric and conductivity anisotropy, curvature elastic torques, and dissipative torques determined by a curvature viscosity.
Anomalous Skin Effect in Thin Films
Authors: Henry G. R.
Published: February 2004

Numerical calculations are presented for the impedance per square of metallic films. We consider in detail the case in which the mean free path of the conduction electrons is comparable to or greater than the film thickness (thin films at low temperatures), with particular attention to the transition between the dc limit and the anomalous skin-effect limit.
Interference Effects Produced by Modulated Particle Beams
Authors: Lipkin H.J. , Peshkin M.
Published: February 2004

The general principles of quantum mechanics imply restrictions upon the time and space dependence of interference effects produced by modulated particle beams. The theorems proved cover a wide range of phenomena, including the production of coherent radiation.
Behavior of Gas Bubbles in Viscoelastic Materials in a Creep Process
Authors: Yang Wen-Jei , Liang C. Y.
Published: February 2004

This paper investigates the dynamic behavior of a spherical bubble situated in viscoelastic (or elasticoviscous) materials in a creep process. Both the diffusion of the dissolved gas in the material and the thermodynamic behavior of the gas inside the bubble are taken into account. The generalized model of the Kelvin or Maxwell type which consists of the spring, dashpot, and Kelvin units is used to describe the creep behavior of the material under combined stresses. The growth or shrinkage of the gas bubble may be induced by a change in the dissolved gas concentration in the material, a change in the external load applied to the material, or a combination of both. Numerical results are obtained for simpler models and the effects of their parameters on the radius-time history of a bubble shrinking in an undersaturated solution or growing in an oversaturated solution are disclosed.
Filter Distortion of Spectral Lines
Authors: Posener D. W.
Published: February 2004

Distortion resulting from the filtering of spectral lines introduces errors in measurement of position, amplitude, and linewidth. Such errors are described here quantitatively and graphically for Gaussian and Lorentzian profiles and for their first derivatives, when distorted by a simple RC filter.
Mode Competition in High-Power Homogeneously Broadened Lasers
Authors: Lax Melvin , Louisell William H. , McKnight William B.
Published: February 2004

Study of mode competition of transverse modes in a high-power homogeneously broadened gas laser with confocal geometry reveals that all transverse modes will be excited by a corresponding longitudinal mode. This applies from very low operating levels all the way to the highly saturated region of operation. Physically the reason is due to the presence of excited atoms along the transverse dimensions of the laser where modes overlap spatially. When apertures are inserted to increase the losses in the higher-order modes, these atoms are not available to supply energy to the desired single mode so that the total output power will be decreased when one goes from multimode to single-mode operation.
Amorphous Semiconducting 3As2Se3·2Sb2Se3 Films. I. Optical Properties
Authors: Chaudhari P. K. , Chenette E. R. , Van Der Ziel A.
Published: February 2004

Transmittance and absorption studies have been made in the 0.7–16-μ range on 60% As2Se3·40% Sb2Se3 evaporated films of amorphous composition to provide information about the optical properties and the energy-band structure. The refractive index shows a sharp increase near the interband transition, and the films do not exhibit free-carrier absorption. The static relative dielectric constant obtained is ε=n2=5.11 The relaxation time for free carriers is τ=1.63×10−15 sec, and the mobility calculated from τ is less than 5 cm2/V sec. The relation α2∼hv near the absorption edge is proposed to be due to the transitions between the localized states in the valence band edge and the nonlocalized states in the conduction band. The thermal coefficient of energy is found to be dEopt/dT=−5.3×10−4 eV/°K, with Eopt (absorption edge extrapolated to α=0)=1.442 eV.
Effect of a Discontinuity in Density or Conductivity on the Hydromagnetic Stability of a Vortex Sheet
Authors: Chakraborty B. B. , Jindia R. K.
Published: February 2004

The hydromagnetic stability of a plane vortex sheet in incompressible, inviscid, and finitely conducting fluids is studied against small disturbances in the presence of a discontinuity in density or conductivity across the vortex sheet. In the equilibrium state the magnetic field is uniform and aligned with the direction of fluid motions. It is found that it is sufficient, for studying the stability of the vortex sheet, to consider only two-dimensional disturbances that travel along the magnetic field. A discussion of the dispersion relation in several different cases shows that a discontinuity in density or conductivity has a stabilizing influence on the vortex sheet.
Mechanism of Sintering in Cobalt Rare-Earth Permanent-Magnet Alloys
Authors: Benz M. G. , Martin D. L.
Published: February 2004

Observations of composition, temperature, and time effects during the sintering of cobalt-samarium permanent-magnet alloys are presented. A correlation between the conditions which lead to the onset of rapid shrinkage during sintering and the conditions which lead to a high Hci is noted. A model for the mechanism of shrinkage during sintering is postulated where the slow step is the diffusion of samarium atoms in the grain-boundary regions via a samarium-atom-cobalt-vacancy cluster exchange mechanism. Furthermore, it is suggested that the ``high'' Hci structures achieved in these alloys would appear to be those with a relatively high concentration of cobalt vacancies in the grain-boundary regions.
A Study on Thin Permalloy Wires by Bitter Patterns
Authors: Ito Noboru
Published: February 2004

Observation of Bitter patterns has long been utilized to study thin magnetic films. All reports published hitherto concern only the case where the film surfaces were flat, because curvature of the film surface of Permalloy wires makes the observation difficult. But domain walls of thin Permalloy wire with the easy axis in the peripheral direction are observed in parallel to the easy axis. The behavior is so simple that the observation of the Bitter patterns offers a convenient way to study thin Permalloy wires. Specimens used are 1-μm-thick 81 Ni Permalloy films electrodeposited onto copper wires with diameters of 0.5 mm, and the uniaxial field-induced anisotropy is in the peripheral direction. Bitter patterns were observed under impressions of magnetic fields, mechanical stresses, plastic deformations, and annealing treatments. Main observations were as follows: The behavior of domain walls under mechanical stresses generally originated around film defects, the dislocation energy of plastic deformations decreased rapidly in accordance with distances from them, and an annealing treatment in a furnace at 100°C for (1/4) h changed the properties of film defects.
Cavity Dumping of a Transversely Excited CO2 Laser
Authors: Patel B. S.
Published: February 2004

Transverse excitation simplifies the cavity dumping of a CO2 laser. An experimental method of cavity dumping a transversely excited system is reported. In the presence of helium the cavity-dumped pulses have a peak power of 120 kW, and in its absence the peak power reduces to 80 kW.
Fracture by Superimposing Stress Waves
Authors: Steverding B. , Austin C. W. , Werkheiser A. H.
Published: February 2004

A stress-wave system of three intersecting waves may be generated by electron-pulse techniques. The waves intersect at an angle of 90° and cause a brittle mode of fracture in the superposition interval in otherwise ductile metals. Fractographic investigation shows a peculiar type of intergranular fracture in which individual grains are separated and rotated. Fracture occurs simultaneously at a multitude of locations where the acoustic impedance between individual grain boundaries is sufficiently large.
Laser-Induced Transmittance and Emission Phenomena in Polycrystalline Semiconductors
Authors: Townsend Charles L.
Published: February 2004

This paper presents results of a study of laser-induced transmittance modulation in, and laser-induced rear-surface thermal emissions from, germanium, silicon, and cadmium telluride. Probable explanations of the observed phenomena of optical transmittance modulation and the burst emission of infrared radiation beyond the transmission cut-on edge of germanium and silicon test samples are presented. Use of the observed phenomena for practical applications is mentioned.
The frequency temperature dependence of coupled extensional, flexural, and width-shear vibrations of rotated X-cut quartz plates
Authors: Lee P.C.Y. , Zelenka J.
Published: February 2004

The frequency temperature dependence of rotated X-cut quartz plates is studied in the case where the presence and coupling of the extensional, flexural, and width-shear modes are taken into account by using a set of one-dimensional approximate equations previously derived. The dependence of the turnover-point temperature as a function of width-to-length ratio for different values of orientation angle, and as a function of orientation angle for various values of the width-to-length ratio, is studied. The predicted results are presented and compared with measured values.
Instability of a drifting semiconductor plasma in a transverse magnetic field
Authors: Burke B.E. , Kino G.S.
Published: February 2004

A new theory to determine the rate of spatial growth of carrier waves propagating in an electron-hole plasma in InSb is derived in this paper. The theory is an extension of previous work on surface carrier waves which takes account of diffusion. The results indicate that the threshold velocity for gain is proportional to the square root of the frequency, and the magnetic field for maximum gain is such that μeB>1. Experimental measurements of growing waves have been carried out using InSb with frequencies in the range 10–180 MHz. Noise measurements which indicated the presence of oscillations due to this same amplification mechanism were carried out at frequencies up to 800 MHz. The observed rates of growth are lower, and the measured threshold velocity is higher than the theory indicates. This is because the Suhl effect is neglected in the theory.
Analysis of plane shock structures in 606-T6 aluminum
Authors: Chang H.L. , Horie Y.
Published: February 2004

The steady profile of plane shocks in 6061-T6 aluminum by Johnson and Barker is compared with the unsteady ones obtained by a finite-difference integration of the Lagrangian dynamic equations. The results purport the conclusions similar to theirs but are not conclusive as they claim. It is also found that strain-rate functions proposed by Johnson and Barker are double valued at high stresses for fixed strains and need to be further clarified in future experiments.
Impact-ionization phenomena in n-InSb subject to transverse magnetic fields
Authors: Pusch F. , Buchegger O. , Paschke F.
Published: February 2004

The dynamic behavior of electric fields, current, and charge densities in a slab of n-type InSb under the influence of a transverse magnetic field and a voltage surge large enough to produce impact ionization has been analysed. Electron-hole-pair distribution is shown to be strongly inhomogeneous. As a result of inhomogeneity, the Hall mobility of electrons decreases with increasing pair density while drift mobility remains unaltered. Current interpretation of Hall-mobility decrease due to electron-hole scattering appears to be insufficient. The theoretical results agree quite well with our own Hall measurements of electron density and mobility, provided surface recombination and the influence of sample length on Hall field at large magnetic fields are taken into account.
Optical properties of glassy carbon from 0 to 82 eV
Authors: Williams M.W. , Arakawa E.T.
Published: February 2004

Optical constants have been obtained for glassy carbon from 0 to 82 eV by means of reflection measurements. The data have been analyzed by analogy with those for graphite in terms of single electron excitations and of collective oscillations of the π and σ electrons.
A comparison of ferromagnetic resonance with magnetic moment and x-ray film thickness measurements for thin Permalloy films
Authors: Bajorek C.H. , Wilts C.H.
Published: February 2004

In an effort to resolve the ambiguity of the source of pinning of the magnetization invoked in spin-wave resonance measurements, a correlation of the ratio of magnetic moment and x-ray film thickness with the value of effective demagnetizing field 4πNM as determined from resonance, for 81% Ni-19% Fe (Permalloy) evaporated films (10−6 Torr) 40 to 400 Å thick, has been performed. The remarkable agreement of both quantities demonstrates that the thickness dependence of both quantities is related to a thickness-dependent average saturation magnetization, which is far below that of bulk material for very thin films. Furthermore, the extent of this agreement strongly suggests the absence of any significant surface anisotropy or an inhomogeneous demagnetizing field caused by surface roughness in such films. However, a series of complementary experiments shows that this large decrease of average saturation magnetization cannot be simply explained by an oxidation process.
Ambipolar diffusion noise in a semiconductor in the presence of a magnetic field
Authors: Maldonado C.D. , Ayala I.L. , Bhattacharjie A.
Published: February 2004

The noise spectrum due to fluctuations of electron-hole pairs in a semiconductor in the presence of a magnetic field when ambipolar drift and generation recombination are the only important noise processes was presented in a previous paper. In this paper the noise spectrum is presented for the opposite case when ambipolar diffusion and generation recombination are the important processes with ambipolar drift being negligible and unimportant. This spectrum was obtained via the Green's function for the macroscopic differential equation which governs the behavior of the conditional average for fluctuations in the electron-hole-pair particle density when ambipolar diffusion and generation recombination are the only important noise processes. From the obtained result for the spectrum, numerical calculations were carried out in order to display the functional dependence of the noise spectrum on frequency and magnetic field strength for fixed ratios of the mean volume lifetime of electron-hole pairs to the characteristic ambipolar diffusion time of electron-hole pairs along the direction of the magnetic field. Finally, it is shown that for high frequencies the asymptotic dependence of the spectrum on frequency obeys the ``universal 3/2 power law''.
Pressure dependence of adiabatic volume viscosity and structure of water using ultrasonics
Authors: Kor S.K. , Rai Gulshan , Awasthi O.N. , Singh B.K.
Published: February 2004

Ultrasonic absorption data have been used to evaluate the mole fraction of the open-packed state, x2, adiabatic volume viscosities ηv and η′v, molal volume difference ΔV, and molal free-energy difference ΔF between the two states of water in the pressure range 1–5000 kg/cm2 at 0 and 30 °C. Variation of ΔV, ΔF, and x2 is in agreement with the previous values obtained up to 2000 kg/cm2. The ratio ηv/η′v is nearly unity at all the pressures.
Acousto-optic property of single-crystal 5PbO·3GeO2
Authors: Ohmachi Yoshiro , Uchida Naoya
Published: February 2004

Acousto-optical figure of merit and acoustic attenuation have been measured for a new ferroelectric material—5PbO·3GeO2. The highest value of M is found to be 22 × 10−18 sec3/g for the longitudinal wave along the X axis. However, a fairly large loss, 2 dB/cm at 100 MHz for this acoustic mode, restricts the acousto-optical device applications of the crystal in the relatively low-frequency region.
Thermal stability of thin PtSi films on silicon substrates
Authors: Sinha A. K. , Marcus R. B. , Sheng T. T. , Haszko S. E.
Published: February 2004

The thermal stability of PtSi is an important parameter in large-scale integration processing schemes which involve postmetallization high-temperature operations. For this reason, the effect of annealing on various properties of PtSi has been studied over the temperature range 800–900°C, for 200- and 900-Å-thick PtSi films on single-crystal silicon substrates. The as-prepared films, produced by backsputter cleaning of Si surface followed by sputtering of Pt, in situ sintering at 700°C for 10 min, and etching to dissolve any unreacted Pt, were found to be single-phase PtSi. The 200-Å-thick PtSi films on (111) Si possess a strong degree of preferred orientation with grains which are triply positioned with (100) PtSi ∥ (111) Si and [010] PtSi ∥ 〈110〉 Si; the orientation remains unchanged upon further annealing. On going to higher thickness (900 Å), the preferred orientation of PtSi changes to (010) type and then to a partial (111) type on annealing at 900°C. Rapid grain growth is observed on annealing in the range 800–900°C; the grain size increases from 0.01–0.25 μ in the as-deposited film to several μ at 850°C. The grain growth is followed at 900°C by agglomeration, i.e., a changeover from continuous film to island-type microstructure. The final stage of agglomeration, which has been observed in 200-Å PtSi at 900°C, is associated with a drastic increase in resistivity. The resistivity of as-prepared PtSi films is estimated to be 15 (±5) μΩ cm. Partial agglomeration of 900-Å PtSi occurs at 900°C; it produces only a 10% increase in resistivity. It is concluded that for PtSi films 200–900 Å thick, 800°C is a safe upper-limit (and 850°C, absolute-limit) temperature below which there is no agglomeration, no change in crystallographic orientation, and grain growth is not excessive.
Computer evaluation of primary deposited energy profiles in ion-implanted silicon under channeling conditions
Authors: Desalvo A. , Rosa R. , Zignani F.
Published: February 2004

Primary deposited energy profiles produced by 40-keV P ions channeled along the [110] direction in silicon are computed. The model takes into account impact-parameter-dependent electronic energy loss and dechanneling mechanisms, such as thermal vibrations, electronic scattering, and a surface oxide layer. The deposited energy is converted to damage by using Kinchin and Pease's model and distributed along the range of primary recoils or dechanneled ions in two ways: either uniformly or localized at the average damage depth, evaluated using Winterbon, Sigmund, and Sanders's theory. The model is tested for the random case with experiments available. When no dechanneling mechanism is present, radiation damage is reduced by a factor of 10 compared to the random case. Thermal vibrations increase damage almost uniformly along all the channeled path, while the oxide layer increases the damage mostly at the surface. The combined effect of these mechanisms gives a reduction of radiation damage of only a factor of [inverted lazy s]2 compared to the random case. The results show also that damage is mostly concentrated at the surface: about 85% in the first 2000 Å compared to a maximum penetration of 7600 Å.
Carrier injection and trapping phenomena in metal-polymer-silicon structures
Authors: Ai Bui , Carchano H. , Sanchez D.
Published: February 2004

Hysteresis phenomena have been observed in capacitance-voltage measurements on metal-polymer-silicon structures, which demonstrate the injection of holes and electrons from silicon and metal electrodes. The dependence of the width of the hysteresis cycle on the sweep-frequency voltage shows that holes or electrons dominate the statistics of charge distribution in polymer traps depending on the sweep rate. dc conduction measurements on these samples showed a linear relation between the logarithm of current and the square root of the voltage. The symmetry of these characteristics indicate a bulk-limited conduction mechanism of carrier emission from polymer traps.
Technique for determining concentration profiles of boron impurities in substrates
Authors: Ziegler J. F. , Cole G. W. , Baglin J. E. E.
Published: February 2004

A new technique is described in detail which can be used to profile boron impurities in almost any substrate to a depth of a few microns. It uses the reaction 10B (n,4He)7Li to convert boron atoms to monoenergetic α particles which are detected after they leave the target. The technique is sensitive to boron at levels as low as 3 ppm, with a depth resolution of ±20/nm for boron in silicon. A new technique of deconvoluting this type of experimental data is described in detail. Methods are presented which eliminate the problem of spurious oscillations in deconvoluted data. Examples are shown in which the technique is used to analyze various distributions of boron in silicon.
Anisotropies in the critical currents of NbN films
Authors: Saito Y. , Anayama T. , Moto Y. , Onodera Y.
Published: February 2004

Anisotropies in the critical currents have been measured for NbN films prepared by reactive sputtering. The Ic values are anisotropic with respect to the orientation of the external field in the plane perpendicular to the direction of the current flow in the film. The effects of the substrate, field strength, and heat treatment on the Ic-θ characteristics were examined. The Ic values show an enhanced peak at θ = 90°, where the external field is applied perpendicular to the film surface. The peak at θ = 90° is explained in terms of the film structure of NbN films, which show a columnar polycrystalline growth.
Bremsstrahlung from cylindrical beta sources
Authors: Harris Dale W. , Silverman Joseph
Published: February 2004

Experimental techniques and equipment were developed for measuring absolute bremsstrahlung spectra from thick cylindrical sources of 147Pm2O3, 204Tl2O3, and 90Sr–90YTiO3. The total bremsstrahlung energy yield for each source was obtained from the photon spectra by the application of calculated corrections for photon absorption in the source, cladding, and air gap. The experimental results are compared with the thin-target theory of Bethe and Heitler, a modified thin target theory that utilizes empirical correction factors proposed by Koch and Motz, and extended by Berger and Seltzer, and Wyard's thick-target approximation. The experimental results are in good agreement with modified thin-target theory, but suggest that the empirical correction factors are too large at energies below 0.2 MeV and too small at higher energies. Dose rates obtained experimentally for 147Pm2O3 and 90Sr–90YTiO3 are compared to those in Arnold's shielding handbook. The handbook results are greater than the experimental values especially for beta emitters with low end-point energies; this arises from the approximate methods used for his self-absorption corrections.
High-resolution spectroscopy for optical probing of continuously generated surface acoustic waves
Authors: Vella P. J. , Stegeman G. I. A. , Zuliani M. , Ristic V. M.
Published: February 2004

Under conditions of continuous acoustic generation, light scattered from oppositely directed surface acoustic waves on y-cut z-propagating lithium niobate was frequency analyzed with a high-resolution Fabry-Perot interferometer. The following parameters were measured at 105 MHz: acoustic power standing-wave ratio, reflection coefficient for both sending and receiving transducers, low-power acoustic damping coefficients, surface wave propagation velocity, and nonlinear harmonic growth. We note that the method used has an advantage over other methods since it is to a large extent independent of the optical quality of the propagation surface.
Microwave ultrasonic attenuation in topaz, beryl, and tourmaline
Authors: Lewis M. F. , Patterson E.
Published: February 2004

Microwave ultrasonic attentuation measurements have been made on single crystals of topaz, beryl, and tourmaline, and all are found to exhibit very low losses. The room-temperature attenuation coefficients are consistent with the Akhiezer mechanism which arises from interactions between the ultrasonic wave and the thermal-phonon assembly.
Anisotropy of radiation damage and dislocation damping in Cu
Authors: Akita H. , Fiore N. F.
Published: February 2004

Cu single-crystal cubes have been γ irradiated in the [001] and [11̄0] directions, and the ultrasonic attenuation due to dislocation damping has been determined in the [110] direction after the various irradiation treatments. Fricke dosimetry indicates that about 10% less secondary electron energy exits the crystal in the [11̄0] irradiation than in the [001] irradiation. The fact that more energy is absorbed in the [11̄0] irradiation is consistent with the dislocation damping studies which indicate that more dislocation-pinning point defects are created in this case. The damping data obey the Granato-Lücke damping theory, and quantitative predictions as to the dislocation loop length and number of pinners created during irradiation are made on the basis of the theory. The anisotropy in radiation damage is consistent with theoretical predictions of anisotropy of replacement energy and focusing energy in Cu.
Depth distributions of defects and impurities in 100-keV B+ ion implanted silicon
Authors: Akasaka Youichi , Horie Kazuo , Yoneda Kiyoshi , Sakurai Teruo , Nishi Hidetoshi , Kawabe Shoji , Tohi Atsutomo
Published: February 2004

The depth distributions of boron atoms and of radiation-induced defects are measured in the same set of silicon samples implanted with 100-keV boron ions at room temperature to a dose of 1×1016/cm2, by utilizing the 11B(p,α)8 Be nuclear reaction and by channeling analysis with 1.5-MeV He+ ions, respectively. Distributions of both boron atoms and the primary defects are asymmetric and significantly deviated from the Gaussian distribution. The width (FWHM) of the damage distribution is about 0.26 μ and is much larger than that of boron distribution which is 0.09 μ. The peak of the primary defect distribution is about 15% shallower than that of the boron distribution. The secondary defects have a Gaussian distribution, the peak depth of which almost coincides with that of boron distribution. The correlation between the electrical and the channeling measurements are also studied, and it is suggested that the secondary defects are strongly associated with boron atoms.
Stress birefringence in ferrimagnetic garnets
Authors: Lynch R. T. , Dillon J. F. , Van Uitert L. G.
Published: February 2004

We have measured the stress birefringence in several magnetic garnets (YIG, YbIG, GdTbIG, and CVBIG) and one nonmagnetic garnet (GdGaG). Measurements were made at room temperature by applying both a static uniaxial stress and a saturating magnetic field along 〈100〉 and 〈111〉 axes. Nonuniformities in the samples and the loading procedure made it valuable to measure the birefringence automatically as a small light spot scanned the crystal. It was found that the photoelastic effect is 2 orders of magnitude too small to account for the linear magnetic birefringence as a birefringence associated with the macroscopic magnetostrictive strain. The stress optical constant B (Δn/stress) in the magnetic crystals was found to be about −1.8×10−13 cm2/dyn for stress along 〈100〉, and −3.0×10−13 for stress along 〈111〉. Diamagnetic GdGaG has values for B of −1.2×10−13 and −3.0×10−13, respectively. It seems plausible then that the tensors describing the photoelastic and magneto-optic effects are not strongly coupled. The dispersion of the stress birefringence is very slight in the range 4000–10 000 cm−1, implying that the photoelastic effect arises from the remote transitions responsible for the refractive index.
Losses in cw dye lasers
Authors: Jacobs R. R. , Samelson H. , Lempicki A.
Published: February 2004

The dynamic loss of a cw dye laser was determined by measuring input-output curves at a fixed wavelength for a variety of wavelengths. The actual losses were obtained from the constants of the straight-line fits for plots of threshold power vs the negative logarithm of the output reflectivity and the inverse slope efficiency vs the inverse of the output mirror transmission. A simplified kinetic-dynamic model of the cw dye laser has been developed to interpret the experimental data. The model is consistent with experiment in the interpretation of the loss information and, with the use of reasonable molecular constants, is also consistent with the dependence of threshold power on the output reflectivity. The actual loss measured is different, at the shorter wavelengths of oscillation, for the two approaches. This difference arises because the population-dependent losses (singlet and triplet absorption of the intracavity laser flux) contribute differently to the efficiency and the threshold. At the longer wavelengths (> 6000 Å) of oscillation these contributions to the loss become very small and the residual scattering, reflection, and diffraction losses remain. The simplified model is successful in dealing with the loss and threshold data and a measure of the triplet-triplet absorption constant can be obtained by combining the kinetic analysis and fitting the threshold power data. The model is less successful in the area of efficiency and this appears to be related to some of the approximations used. A single numerical correction factor, however, brings the efficiency data into reasonable agreement with the model.
Effect of complex formation on diffusion of arsenic in silicon
Authors: Fair Richard B. , Weber Gary R.
Published: February 2004

When As diffuses into Si, only a fraction of the As remains electrically active. Because of the importance of As as an emitter dopant, it is necessary to understand the nature of the inactive As and how it affects the solubility and diffusion of As+ ions. A model is proposed in which As+ diffuses via a simple vacancy mechanism while in quasiequilibrium with [VSiAs2] complexes. The flux of mobile monatomic As+ is modified according to the extent of [VSiAs2] complex formation. The structure of this defect and its formation energy (≈ 1.8 eV) are discussed. An effective diffusion coefficient is derived using this model: DAs=2DiCA /(1+8 K2′ CA3) where CA is the As+ concentration and K2′ is a collective parameter that depends upon As+ surface concentration and the diffusion temperature. Experimental verification of the correctness of this equation is given. The important results of this quantitative analysis show that DAs reaches a maximum value with increasing As concentration, and then decreases monotonically. The As concentration at which Dmax occurs is dependent upon the total As surface doping and the diffusion temperature. The ratio of total As to electrically active As+ decreases to a value of unity at 1300 °C. At 1250 °C it is shown that the solubility of As+ reaches a maximum value of 1.5 × 1021 atoms/cm3 in p-type Si and 1.2 × 1021 atoms/cm3 in n-type Si.
Satellite dimensional resonances in microwave helicon transmission through semiconductors
Authors: Vassallo Charles
Published: February 2004

The classical experiment of the microwave transmission through an axially magnetized semiconductor sample filling a waveguide is analyzed in terms of modal analysis, with a direct use of the guided helicon modes and of their adjoint modes. The validity of the numerical results is established by directly checking the continuity of the transverse components of the electromagnetic field through the vacuum semiconductor junctions. The calculation predicts satellite dimensional resonances, due to the higher helicon modes. These satellite resonances disappear if sufficient inhomogeneities, i.e., carrier density fluctuation of about 10%, are introduced in the mathematical model of the sample.
Effect of compressive stress on silicon bipolar devices
Authors: Kanda Yozo
Published: February 2004

The calculation for the compressive stress dependence of silicon diode current is refined for the 〈100〉 and 〈111〉 crystal orientations. The stress dependence of the density-of-states effective masses of hole bands is taken into account on the basis of Hasegawa's theory. An anomalous peak is predicted at a stress of ∼ 109 dyn/cm2 due to the stress dependence of the heavy hole effective masses. For the 〈111〉 orientation, a small minimum appears at a stress of ∼ 108 dyn/cm2. The stress dependence of the common-emitter transistor current gain β can be explained by the combined effects of the stress dependence of the emitter efficiency related to the above-mentioned calculation and the stress dependence of the base transport factor. The difference of stress dependence of β between n-p-n and p-n-p transistors can also be explained. It is predicted that β goes through a minimum at a stress of ∼ 109 dyn/cm2. Suggestions concerning thermal stress on transistors in large-scale integration are made.
Absorption tail and fundamental absorption edge in vanadium phosphate glasses
Authors: Anderson Gordon Wood
Published: February 2004

Optical measurements of the fundamental absorption edge and broad absorption tail of 50 mole% V2O5 vanadium phosphate glass films were made in the range 3850–30 000 cm−1 (2.6–0.33 μ) before and after reducing and oxidizing anneals. The absorption in the tail region of the fundamental absorption increased during reducing anneals and decreased during oxidizing anneals. A band at 19400 cm−1 (2.41 eV) was introduced by the reducing anneals. The band gap Eg was determined to be 2.71, 2.92, and 2.82 eV after successive anneals in oxygen, hydrogen, and oxygen, respectively. Evidence for direct forbidden transitions was observed from fundamental absorption edge measurements similar to that for crystalline V2O5. The concentration of reduced V4+ ions is concluded to be largely responsible for the variation of Eg and of the absorption tail.
Manganese gallium germanide-a new ferromagnetic material
Authors: Street G. Bryan , Sawatzky Erich , Lee Kenneth
Published: February 2004

A new ferromagnetic ternary compound MnGaGe, isostructural with Mn2Sb, has been prepared by quenching from the melt and subsequent solid-state reaction. The metallic MnGaGe is tetragonal with lattice constants a = 3.966±0.001 Å and c = 5.885±0.001 Å. Magnetic measurements show that the Curie temperature is 185 °C and the saturation magnetization corresponds to 1.66μB/Mn atom at 4.2 °K. The easy axis of magnetization coincides with the crystallographic c axis. The new material is thermally stable to 616 °C at which temperature it melts peritectically.
Laser evaporation and elemental analysis
Authors: Kliwer J. K.
Published: February 2004

The preparation of thin uniform targets from multielemental samples by pulsed-laser evaporation is described. The targets are useful in trace elemental analyses employing x-ray or charged-particle excitation of inner-shell electrons. The results of brass and tool-steel analyses are presented as a demonstration of the potential of this application of laser evaporation.
Behavior of magnetophotoconductivity of semi-insulating GaAs upon α-particle bombardment
Authors: Euthymiou P. C. , Nomicos C. D. , Philadelpheus A. Th.
Published: February 2004

The effect of 2-MeV α-particles on the magnetophotoconductivity of semi-insulating GaAs single crystals mounted in the Voigt geometry has been investigated at 300°K. Upon bombardment of the specimen we found an increase of the positive branch of the magnetophotoconductivity while the negative branch remained unaltered. The increase is attributed to a decrease of carrier lifetime in the damaged surface region. The negative branch remains constant since the α-particles do not influence the bulk properties.
Photoelectric spectral response of certain solids
Authors: Jones J. E.
Published: February 2004

Data taken from the literature on a variety of photoelectric effects are analyzed considering that the maximum photoresponse occurs at the wavelength at which the absorptance of the volume element responsible for the photoeffect is a maximum. The spectral response of certain photosensitive systems is shown to parallel the absorption of a thin volume element next to the rear surface. The thickness of surface recombination layers for cadmium sulfide is estimated from calculations involving the transmittance of the sample at the wavelength at which the maximum photoresponse occurs and the thickness of the sample.
Growth direction of polyoxymethylene crystals inside irradiated trioxane crystals
Authors: Colson J. P. , Reneker D. H.
Published: February 2004

The long slender crystals of polyoxymethylene that grew in irradiated trioxane crystals all grew toward the negative end of the trioxane crystal. The observed direction of growth was consistent with the assumption that the ion at the growing end of the polyoxymethylene chain was a cation. Certain morphological features such as facets and direction of taper of these polyoxymethylene crystals indicated the direction in which the crystals grew. Incidental observations of polyoxymethylene precursor crystals, electret domains in trioxane, and the effects of electron irradiation on polyoxymethylene crystals were made.
Morphology of plasma-polymerized ethylene
Authors: Niinomi M. , Kobayashi H. , Bell A. T. , Shen M.
Published: February 2004

A highly crosslinked amorphous polymer is produced by passing ethylene through a radio-frequency electric discharge. The morphology of plasma-polymerized ethylene is examined by replica electron microscopy. It is found that at low pressures and flow rates spherical powder particles are formed ranging in size between 0.2 and 1.2 μm. At high pressures and flow rates a film is formed. The role of the substrate on which the polymer is deposited has been investigated using chromium, Teflon, glass, and freshly cleaved mica as substrates. These materials are listed in order of increasing smoothness. From the electron micrographs it is observed that the surface structure of the substrate is reproduced in the plasma-polymerized films as long as the film is thin ([inverted lazy s] 0.5 μm). Thicker films produced by a longer exposure to the ethylene plasma are characterized by a surface which is smoother than that of the substrate.
Digital computer studies of electron lenses for cathode-ray tubes
Authors: Saito Tsunenari , Kubota Shigeo , Miyaoka Senri
Published: February 2004

The focal properties and the third-order aberration coefficients of a number of unipotential lenses and a bipotential lens were investigated numerically using digital methods. The differential quotients of aberration coefficients in terms of the entrance pupil position were obtained in excellent agreement with those given by Berek in glass optics. The aberration coefficients were also calculated under the Fraunhofer condition for an infinite image position. For a fixed focal length, spherical aberration coefficients decrease and astigmatism coefficients increase as the length of the center electrode increases for equidiameter unipotential lenses. The symmetrical bipotential lens is almost astigmatism free for various voltage ratios; however, its spherical aberration coefficient is two to five times larger than those of equidiameter unipotential lenses operated at the same focal length.
Photoluminescence of ion-implantation-damaged n-type GaAs
Authors: Summers C. J. , Miklosz J. C.
Published: February 2004

The effect of neon implants on the photoluminescence spectrum of heavily doped n-type GaAs has been determined. A large decrease in the photoluminescence efficiency is observed upon implantation, the magnitude of which depends on the ion dose and excitation wavelength. A model which explains the decrease in minority carrier lifetime and, therefore, the bulk quantum efficiency, is presented. The wavelength dependence is explained by the degree of overlap between the optical absorption length and the ion range.
Faraday rotation and optical absorption of a single crystal of bismuth-substituted gadolinium iron garnet
Authors: Takeuchi Hiroshi , Ito Shin-ichi , Mikami Itsuo , Taniguchi Satoshi
Published: February 2004

Faraday rotation and optical absorption of a single crystal of bismuth-substituted gadolinium iron garnet were measured in the near-infrared region. In spite of the remarkable increase of rotation by the bismuth substitution, no appreciable increase of absorption coefficient was observed in this wavelength region.
New multicolor liquid crystal displays that use a twisted nematic electro-optical cell
Authors: Scheffer Terry J.
Published: February 2004

Two new variable color display device arrangements are described. These arrangements combine the unique polarization switching capabilities of the twisted nematic liquid crystal electro-optical cell with the anisotropic optical properties of separate passive optical elements. In one scheme, the passive element is a birefringent film in combination with a neutral polarizer, and colors are transmitted by the selective interference of white light. In another design, where the passive element is a pleochroic filter, the transmitted colors result from the selective absorption of white light. These arrangements make possible large area displays, since the colors transmitted do not depend on the temperature or thickness of the nematic layer. Transmission curves and other color information are given for a number of examples.
Holographic interferometry of exploding wires
Authors: Seftor Jeffrey L.
Published: February 2004

A short (2-nsec) pulse ruby laser has been used to make holographic interferograms of exploding-wire events. At atmospheric pressure the interferograms exhibit both shock waves and ionization. In a vacuum the vaporization and subsequent ionization of the wire are evident. At selected times after initiation, spatial electron density profiles have been calculated via an Abel inversion, with peak densities approaching 1019 cm−3.
On the grain boundary diffusion theory of Fisher and Whipple
Authors: Young Gale , Funderlic R. E.
Published: February 2004

The theory of diffusion in grain boundaries was initiated by Fisher, using an idealized model in which a poorly diffusing half-space (the crystal) is bisected by a thin well-diffusing slab (the grain boundary), with a fixed concentration of diffusing material suddenly established at the free surface. In the present paper we first improve Fisher's result by removing one of his approximations. We then generalize Whipple's later exact solution to include anisotropic diffusion in the crystal, and other changes; the generalized theory now contains both the original Whipple result and the improved Fisher result as special cases and displays individually the effects of the different assumptions.
Application of intense relativistic electron beams to microwave generation
Authors: Carmel Y. , Nation J. A.
Published: February 2004

Experiments have been carried out to investigate the processes leading to the generation of intense microwave signals, resulting from the nonadiabatic motion of an electron beam along a rippled magnetic field. The observations made are consistent with an instability occurring when phase-matching conditions for a cyclotron wave on the beam and a waveguide mode are satisfied. The injection of the beam through the rippled field then serves the primary purpose of converting some of the electron motion from the parallel to the perpendicular sense. The microwave signal is maximized when this conversion is most efficient. Measurements are reported of diamagnetism, beam drift currents, and the microwave power and frequency spectrum. The results presented are interpreted as far as possible using existing theories.