bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytic solutions for the response and natural frequencies of a delay line
Authors: Hultsch R. A. , Wang Y. Y. , Lee K. H.
Published: February 2004

The closed-form analytic solution for the response of a lossless delay line is presented. The effects of all signal reflections to infinite order from both ends of the line are explicitly taken into account. In contrast with the conventional analyses, in which the natural frequencies of the circuit are given as the roots either of the transcendental equation or of a polynomial of degree equal to the number of LC sections, a simple analytic expression for the frequencies has been obtained. Thus, the present result enables one to avoid having to find approximate numerical solutions for the frequencies. The validity of this expression is demonstrated by comparison with a numerical calculation using the conventional method and with an experiment on a ten-section line of high-Q elements.
Experimental results for extending the Rice-Walsh equation of state of water
Authors: Baconin J. , Lascar A.
Published: February 2004

Walsh and Rice have developed a model for the equation of state for water valid from 25 to 250 kbar. We present here the results of the experiments undertaken to extend the validity of this equation up to 1.5 Mbar.
One-dimensional radiative energy transfer in thin layers of fibrous materials
Authors: Davis L. Berkley , Birkebak Richard C.
Published: February 2004

A general model for one-dimensional radiative energy transfer through a bed of fibrous materials is presented. The end result is the radiative thermal conductivity as a function of bed thickness, fiber emittances, volume fraction occupied by the fibers, and the average fiber diameter. Any general geometrical model of the arrangement of the fibers in the bed can be used in this model. For comparison purposes, a bed with randomly oriented fibers is considered.
Coherence of an electromagnetic field propagating in a weakly guiding fiber
Authors: Crosignani B. , Di Porto P.
Published: February 2004

The coherence of an electromagnetic field propagating in a weakly guiding cylindrical fiber supporting many modes is examined. In particular, the complex degree of coherence is a periodic function of the traveled distance z for small z. For large z, the degree of coherence does not depend on z at equal times, while, as a function of time, it possesses a series of maxima with spacing dependent on z.
Excitation mechanisms in He–Cd and He–Zn ion lasers
Authors: Collins G. J.
Published: February 2004

Experimental evidence from pulsed afterglow studies is presented which demonstrates that thermal energy charge transfer is the primary source of excitation for the high-lying Zn II and Cd II laser levels, with configurations of the type 3d 10nx and 4d 10nx, respectively, whereas the main source of excitation of the Zn II and Cd II laser levels, with configurations of the type 3d 94s 2 and 4d 95s 2, is Penning ionization. The total velocity-averaged cross sections for thermal energy charge exchange and for Penning ionization are measured to be of order 10−15 cm2. These large cross sections account for the relatively high efficiency and low threshold currents characteristic of He–Zn and He–Cd ion lasers. The intensity of spontaneous emission from laser levels excited in a flowing afterglow by charge-transfer reactions is broken down into the component contributions: direct charge-transfer excitation, radiative cascade, and collisional cascade excitation. The results are used to estimate the values of the individual cross sections for direct charge transfer into Zn II and Cd II laser levels. The potential of thermal energy charge transfer as a general excitation scheme for gaseous lasers is illustrated by several new proposals for new cw laser transitions in the region between 2000 and 4000 Å.
Mode guidance parallel to the junction plane of double-heterostructure GaAs lasers
Authors: Nash F. R.
Published: February 2004

We investigate the origins of mode confinement, parallel to the junction plane, of stripe-geometry double-heterostructure GaAs injection lasers. Based upon the kind of control of the mode extent by the stripe width, we establish a distinction between two types of lasing mode guidance; (i) well-behaved, where a single mode substantially fills the entire active region, and (ii) filamentary, where the mode size is much smaller than the width of the active region and its location is random. For low-order well-behaved modes, it is shown, at least in principle, that gain alone (no refractive index effects are required) can explain not only the confinement but also the approximate waveguide dimensions for which leakage losses, connected with the penetration of the mode into the regions outside the active guide, become important. When only this postulated gain-guiding prevails in the case of higher-order modes, we find that their spatial character is markedly different from the Hermite-Gaussian distributions which have been seen for GaAs lasers. The introduction of a positive incremental index, which may reasonably be associated with the gain and/or with a thermal mechanism, restores agreement with observation. If any incremental index within the active region is negative, then although there is a defocusing effect, confinement may still be maintained by the gain. In the case of filamentary lasing we analyze four focusing mechanisms; two are connected with local built-in gain (loss) and refractive index variations, while two are current dependent and are related to the saturation of gain-associated refractive index and the free carrier effect. While all four processes appear to be reasonable candidates for providing the necessary confinement in filamentary lasing, the latter two simultaneously violate a condition necessary for stability of a filament. We conclude that imperfections in lasers are likely to be related to filamentary lasing and that such behavior may not be intrinsic to such devices.
Superconducting objective lens utilizing field trapping in Nb3Sn disks
Authors: Hibino Michio , Hardy David F. , Plomp Fredrick H. , Kawakatsu Hisazo , Siegel Benjamin M.
Published: February 2004

A high-quality superconducting objective lens has been designed, and the optical characteristics have been tested in a conventional electron microscope. The lens uses Nb3Sn disks held in the gap of a ferromagnetic container. The magnetic field is trapped in the disks using an excitation coil that is then deenergized leaving a persistent field that has a Gaussian distribution. Using a stack of 20 disks in a gap of 2.5 mm with a bore diameter of 3 mm, a peak field of 22 kG and a half-width of 1.76 mm is produced. The spherical and chromatic aberration coefficients given by this field have been calculated. The lens was tested in an experimental cryostat mounted in the column of an Hitachi HU-11A. The images obtained showed reasonable quality with the resolution limit of 10 Å set by mechanical instabilities.
A new proposal for the focusing of microwaves in nonparabolic semiconductors: Application of inhomogeneous quantum magnetic fields
Authors: Phadke U. P. , Chakravarti A. K.
Published: February 2004

It is shown that the magnetic-field-dependent effective mass of electrons alone in nonparabolic semiconductors subjected to a suitably designed cylindrically symmetric inhomogeneous quantum magnetic field can lead to periodic focusing of low intensity microwaves. Typical parameters for the case of an n-InSb sample yield a focusing length varying from 5.0 to 0.5 cm when the magnetic field is reduced by 10% to 100% in going 0.1 cm away from the axis of the beam where the magnetic field is [inverted lazy s] 100 kG.
Appearance potential spectroscopy: Recapitulation
Authors: Tracy J. C.
Published: February 2004

We point out that the recent appearance potential spectroscopy (APS) results of Park and Houston on Si are consistent with our previous results.
Nonlinear interaction of acoustic surface waves from coupling to charge carriers
Authors: Lee C. W. , Gunshor R. L.
Published: February 2004

Experiments on frequency mixing show that up and down conversion is enhanced over results reported for lithium niobate alone. Convolution experiments with a transverse electrode configuration show a similar enhancement. In addition, it is shown that one may represent the convolver with a load-independant voltage element in the linear response region; but when saturation begins, this source becomes dependent on load current. Experiments are reported which demonstrate how one signal may be used to vary the attenuation of another.
Transient behavior of the electrically controlled birefringence in a nematic liquid crystal
Authors: Labrunie G. , Robert J.
Published: February 2004

An homeotropic cell is built with a thin layer (5–25 μm) of nematic liquid crystal such as MBBA sandwiched between two indium oxide coated glass plates. The transient behavior of the cooperative angular variation of molecules submitted to an electric field step is studied theoretically. Experimental results are obtained by optical detection of the birefringence variations in the cell. Comparison of these studies allows one to determine the viscosity coefficient γ1(−λ1 in Leslie's notation).
Compression of relativistic electron beams in magnetic materials
Authors: Green Milton
Published: February 2004

By superimposing a coaxial conduction current on the beam current of relativistic electrons passing through high-permeability magnetic materials, the Lorentz field, β × B, can be made an appreciable fraction of the stopping electric field, G = e−1 dU/dz, of the electron in the material, implying that a state of compression is quite possible. A model of the repulsive field Eσ for the electron beam, arising from momentum being scattered radially from the axial momentum of the beam, is given. The equation of the resultant field acting on an electron provides the information to determine the condition for a pinch to occur. Experimental means of interpreting the results are indicated.
Radial neutral gas temperature and density profiles in low-pressure argon discharges
Authors: Eden J. G. , Cherrington B. E.
Published: February 2004

In this paper we describe the direct measurement of the neutral gas density and the determination of the neutral temperature profiles in a low-pressure weakly ionized argon discharge. The measurements were made using a single-wavelength coupled cavity laser interferometer to study the neutral density variations in the afterglow of a crowbarred dc (steady-state) discharge. The temporal and radial variations of the neutral gas density in the afterglow were used to infer the dc steady-state gas density and temperature profiles, assuming an ideal gas. It is shown that the profiles are strongly current and pressure dependent and that the axial depletion of neutrals can be as high as 25–30%. Long neutral relaxation times (2–3 msec) were encountered in order to reach thermal equilibrium in the afterglow for the pressures and currents studied (1–10 Torr, 50–350 mA). Radial profiles of the neutral gas density for a fixed pressure and current are in agreement with the hypothesis that neutral heating is caused primarily by collisions with the electron gas, resulting in a convective flow of the hot neutrals radially outward towards the cooler walls.
Optical diagnostics of an ECRH plasma
Authors: Eastlund B. J. , Spero D. , Johnson M. , Korn P. , Wharton C. B. , Wilson E. R.
Published: February 2004

Line ratios and absolute intensities of helium singlet and triplet states are used to determine the electron temperature and number density of an electron cyclotron resonance heated (ECRH) plasma. Excitation rates and line ratios are calculated using the best available cross-section information. An averaging technique based on absolute intersities is used to determine the temperature. This technique permits an experimental calibration of line ratios. In particular, the ratio of the 4713-Å intensity to the 4921-Å intensity is found to be strongly dependent on electron and neutral atom number densities. The ratio of the intensities of the 5048-and 4713-Å lines is also studied. These results show that the helium line ratios can be used to obtain accurate information on the temperature and number density of an ECRH plasma.
Dissipation function of a viscoelastic material with temperature-dependent properties
Authors: Ting Edward C.
Published: February 2004

An approximated energy equation is derived with the dissipation function expressed in terms of the loss modulus and the strain components. The equation is suitable for the analysis of the thermomechanical behavior of a viscoelastic material subjected to cyclic loadings. The material is assumed to be linear, homogeneous, and isotropic. Its mechanical properties are temperature dependent and satisfy the time-temperature equivalence.
Ga(AsP) light-emitting diode formed by ion implantation
Authors: Itoh Tadatsugu , Oana Yasuhisa
Published: February 2004

Hot ion implantation as a doping technique was used for the fabrication of visible-light-emitting diodes with GaAs1−xPx(x = 0.38 ± 0.01). Zinc ions, p-type dopants, were implanted into n-type (001)-oriented heteroepitaxially grown Ga(AsP)-on-GaAs substrates at 400°C with an energy of 20 keV. Then, thermal treatment at various temperatures was carried out on the sample in order to investigate the effect of annealing on the electrical properties of Zn-implanted layers in the Ga(AsP) substrate. The p-type layer, which was obtained by the ion implantation of 2 × 1015 Zn ions/cm2 with subsequent annealing at 900°C for 40 min, was found to have an effective surface concentration of 1.7 × 1015 carriers/cm2 and a sheet resistivity of about 100 Ω/sq. Red-light-emitting Ga(AsP) diodes fabricated using Zn ion implantation have usually shown an average brightness of 400–600 fL, and sometimes as high as 850 fL at a current density of 10 A/cm2. Diodes, which were formed by means of a standard Zn diffusion technique in an evacuated ampoule at 750°C for 30 min using a ZnAs2 source, had an average brightness of 350–500 fL at the same current density.
Electroluminescence of Gd3+-doped CdF2 in a light-emitting diode
Authors: Yaney Perry Pappas , Bafico Michael A.
Published: February 2004

Light-emitting diodes were fabricated using CdF2 (0.02% Gd3+) which had been converted to the n-type semiconducting state by heating in cadmium vapor. The electroluminescence was observed at the negatively biased blocking electrode with thresholds ranging between 5 and 15 V applied. The emitted light consisted of the expected characteristic near-uv spectra of Gd3+ (2780 and 3120 Å) and a previously unreported 3000-Å-wide band centered at about 4500 Å. The power efficiency was very low and the radiant power output had an approximate cubic dependence on the diode current. Observations made on samples doped with Nd3+, Eu3+, and Tb3+ are also described. All observations were made at room temperature.
Modeling of a pulsed CO/N2 molecular laser system. II. Effect of mixture components and temperature variation
Authors: Fisher Edward R.
Published: February 2004

The CO molecular laser model described in a previous publication has been used to investigate the effect of molecular mixture components and kinetic temperature variations on improving the gain of low-lying CO infrared transitions. Gas mixtures involving diatomic molecules with both larger and smaller vibrational level spacing than CO are investigated. Vibrational pumping of CO by a molecule having a smaller vibrational spacing leads to negligible laser gain predictions due to the nonspecific nature of vibrational exchange processes. The largest predicted gain in the low-lying transitions of CO is found for N2/CO mixtures at 77°K in which appreciable gain in the 2–1 transition is found.
Degradation in long-pulse dye laser emission under fast-flow conditions
Authors: Varnado S. G.
Published: February 2004

A system for providing ultrafast transverse flow in a flashlamp-pumped liquid organic dye laser is described. The effect of flow rate on laser output energy is discussed, and a degradation effect is noted which worsens as the flow rate increases. Degradation is attributed to the formation of scattering centers in the lasing medium during the flow cycle.
Magnetic bubble analog simulator
Authors: Nelson T. J. , Rosencwaig A. , Zappulla R.
Published: February 2004

A mechanical simulator of field-access magnetic bubble devices has been constructed and tested. Bubbles, represented by permanently magnetized cylinders, 0.1 in. in height and 0.15–0.30 in. in diameter, move through oil in response to poles induced in 1/32 in. mu-metal circuit features by a rotating in-plane magnetic field. By strobing the motion of a bubble under a 0.5-in. disk, an equivalent coercivity of 1 Oe and mobility 0.5 in./sec Oe were inferred. Inertia and parasitic drag are estimated, and it is concluded that the viscous damping model with coercivity is valid for the analog device. A T-bar corner is shown which was designed on the simulator and has been tested with real bubbles up to the expected frequency limit.
Faraday rotation in Ce(PO3)3 glass at liquid-helium temperatures
Authors: Wertheimer M. R.
Published: February 2004

Faraday rotation and susceptibility measurements have been carried out at liquid-helium temperatures in nominally pure samples of paramagnetic cerous metaphosphate glass. The Faraday rotation was studied for λ = 546 nm at temperatures between 4.21 and 1.45 K in magnetic fields up to 33 kOe. As reported earlier by Alers (Ref. 1), the rotation can be represented by the expression θ=θ∞ tanh(μH/kT) + BH, where θ∞ is proportional to the concentration of cerous ions and μ is an effective magnetic moment. Nominally identical samples from different melts showed the same rotation at saturation, θ∞=(4.70±0.06)π rad/mm, but differed in their μ values by more than 25%. This is believed to be caused by differing degrees of short-range order which influence the net crystalline field ``seen'' by an average ion. The Faraday rotation thus appears to be a powerful technique for detecting variations in short-range order in amorphous magnetic materials.
Calculation of composition of dilute cosputtered multicomponent films
Authors: Hanak J. J. , Bolker B. F. T.
Published: February 2004

A method for calculating the composition of cosputtered films from calculated deposition profiles and measured film thicknesses has been shown to be applicable to high concentrations of each of the components. Four new modifications are described for concentrations ranging down to 0.1% or less, which employ alternate ways of determining deposition rates. Several examples of cosputtered Cu–Ni alloys show that the rms accuracy of the methods is about 25% of the amount of the solute. Cosputtered films of Al–Si so analyzed have been used as standards for instrumental methods of analysis.
Photoionization of magnesium and copper phthalocyanine in oxygen and hydrogen
Authors: George Aleyamma
Published: February 2004

The photoionization energies of magnesium phthalocyanine (MgPC) and copper phthalocyanine (CuPC) single crystals are determined in different ambient atmospheres by an electrostatic method. The sample crystal is suspended by a quartz fibre in an electric field between two capacitor plates, and the onset of ionization with photon energy is determined through the potential required to restore zero deflection. Results of threshold energy φ for MgPC and CuPC crystals in a clean ultrahigh vacuum of 10−9 Torr and the changes in φ produced by adsorption in 10−2 Torr oxygen and hydrogen atmosphere are presented. The φ values in vacuum obtained here are comparatively lower than those reported by previous workers. The striking features observed in the adsorption of oxygen and hydrogen are that the classic electron donor, hydrogen, raises the threshold of ionization whereas oxygen does not effect any change in the threshold from its value in vacuum. Experiments have also established that MgPC and CuPC do not exhibit a double quantum photoemission.
Preparation and some properties of ZnSnSb2
Authors: Scott Walter
Published: February 2004

Hall coefficient and resistivity measurements on ZnSnSb2 grown from a Sn solution show the material to be degenerately doped p type with a carrier concentration of 1019−1021/cm3 depending on growth procedure. The optical absorption coefficient increases gradually over the range 0.4–1.0 eV with structure at 0.7 eV.
Positron annihilation and average molecular weight of polymers
Authors: Chuang S. Y. , Tao S. J.
Published: February 2004

The positron annihilation mean lives in a polymer are found to be related to the weight-average molecular weight of the polymer.
Short-wavelength edge emission bands in undoped cadmium sulfide
Authors: Greene Lawrence C. , Wilson Henry A.
Published: February 2004

A pair of bands appearing at 4857.2 and 4864.3 Å in the low-temperature emission spectrum of cadmium sulfide is described. These bands are separated by 3.8 meV. It is shown that they may be explained by a model involving transitions from a pair of shallow donors to the valence band, and hence may be classified as edge emission bands.
Comment on ``Temperature-dependent ferroelectric domain alignment in PLZT ceramic''
Authors: O'Bryan H. M. , Maldonado J. R.
Published: February 2004

The domain alignment argument offered by Salaneck to explain the ferroelectric behavior of the PLZT ceramics is shown to be inadequate with respect to the decreased light transmittance of poled material. Rather, a field-induced phase transition to a strongly anisotropic structure provides an adequate answer for the observed light scattering behavior.
Pyroelectric response to single infrared laser pulses in triglycine sulphate and strontium-barium niobate
Authors: Lavi S. , Simhony M.
Published: February 2004

Expressions are derived for the pyroelectric (PE) voltage response to single ir laser signals much shorter than the thermal time constant τT of the PE sample. It is shown both analytically and experimentally that when the electronic time constant τe is much shorter than the time characteristics of the signal, then the response exactly follows the signal and has a peak voltage Vp proportional to the load resistance RL. In the opposite case, the response rises as long as the signal persists, reaching a peak value proportional to absorbed energy but independent of RL, then decays exponentially with falltime τe ∝ RL, as long as τe≪τT.
Temperature study of the polarized Raman spectra of strontium barium niobate
Authors: Bartlett K. G. , Wall L. S.
Published: February 2004

The temperature dependence of the low-frequency spectra of strontium barium niobate is studied from 5 to 850 cm−1. Several modes are identified and their temperature dependence qualitatively correlated to the displacement of various ions as the transition temperature is approached.
Hall coefficient of vanadium carbide as a function of temperature and carbon concentration
Authors: Shacklette L. W. , Ashworth H.
Published: February 2004

The Hall coefficient R of single crystals of vanadium carbide (VCx) with carbon-to-metal ratios (x) ranging from 0.83 to 0.88 were measured between 4.2 and 300 K. The behavior of R versus T is found to depend critically on x, as well as the type of ordered structure (V8C7 or V6C5) present. The data are interpreted in terms of a two-band model which allows for the effects of anisotropic scattering. It is proposed that a minimum in R (x) at x = 0.875 (V8C7) results from an increase in relaxation time, rather than a change in band structure for the ordered compound. The two-band analysis is consistent with the specific heat data of Lowndes, Finegold, and Lye which show a maximum in the density near the ordered compound V6C5.
Backscattered electrons from semiconductors and their effect on the resolution of TSEM
Authors: Kennedy A. J. , Kalweit H. W.
Published: February 2004

The electron backscattering properties of clean Ge(100), GaAs(100), GaAs(111)B, Ga70Al30As(111)B, GaP(111)A, and Si(100) surfaces are studied in the 0.08–3-keV range at pressures below 50 pTorr. The kinetic energy distribution and the backscattered yield η(Er, Ep) are measured by ac and dc retarding field methods. The data on backscattering is used to estimate the influence of high-energy backscattered electrons on the resolution of Si and GaAs transmission secondary electron multipliers. The results show that the degradation in the modulation transfer function at low spatial frequencies is approximately 8% for GaAs and less than 4% for Si.
Calculated energy distributions of electrons emitted from negative electron affinity GaAs: Cs–O surfaces
Authors: Escher J. S. , Schade H.
Published: February 2004

The energy distribution of electrons emitted from negative electron affinity (NEA) GaAs: Cs–O has been calculated for various doping concentrations (1 × 1018−2 × 1019 cm−3) and work functions (0.95–1.15 eV). It has been assumed that electrons to be emitted have thermalized at the bottom of the conduction band when they reach the surface bent-band region. The energy distribution of the electrons reaching the surface is determined by their interactions in the bent-band region and is calculated from a solution of the Boltzmann transport equation. Multiplication of this distribution with an energy-dependent transmission probability for the surface barrier yields the energy distribution of the emitted electrons. The width of the bent-band region, and thus the doping concentration of the emitter material, has a significant influence on the shape and width of the distribution and on its location on the energy scale, while the work function mainly affects the magnitude of the distribution. Measured half-widths of the energy distributions from NEA GaAs photocathodes and cold cathodes are in good agreement with the calculations.
Thermoelectric power of thin silver films
Authors: Yu Ho-Yuan , Leonard William F.
Published: February 2004

Measurements of thermoelectric power, resistivity, and the temperature coefficient of resistance have been made on annealed silver films. The values obtained for the energy dependence of the mean free path of conduction electrons, [(∂ lnλ/∂ lnW)]W=WF, and the Fermi surface area, [(∂ lnA/∂ lnW)]W=WF, were 1.29 and −2.45, respectively.
Measurement of electron density in a cylindrical inertial electrostatic plasma confinement device
Authors: Meeker D. J. , Verdeyen J. T. , Cherrington B. E.
Published: February 2004

This paper reports on an experimental investigation of the spatial variation in electron density in a cylindrical inertial-electrostatic plasma confinement device. A microwave cavity operating at 4 and 8 mm employing both longitudinal and transverse modes and a laser heterodyne system operating at 3.39μ were used to investigate the charge structure. The microwave data showed a nonlinear increase in electron density as a function of center electrode current, implying trapping for ion injection. The laser heterodyne data showed a distinct oscillatory form of electron density as a function of radius for both electron and ion injection, with densities of 8×1011 electrons/cm3 and variations in maxima to minima exceeding 30% of the average density.
Effects of secondary electron scattering on secondary emission yield curves
Authors: Dionne Gerald F.
Published: February 2004

The power-law and constant-loss theories of secondary electron emission have been modified to include the effects of secondary scattering within the solid. For power-law exponent values of 1.35, 1.66, and 2.00, the scattering effects reduced penetration depths at maximum yield by almost a factor of 2 and decreased the maximum yields by about 70% in each case. Reduced yield curves were also computed for the different cases and the results indicate that scattering has only a small effect on the shape of the curves. Where reduced yield curves are involved, it may be concluded that the simpler theories could be sufficiently accurate in many cases. It is also shown that the exponent value of 1.35 provides reasonable agreement with experiment for lower primary energies, while 1.66 is more suitable at higher energies, in general accord with the energy ranges employed in the electron transmission measurements from which the above exponent values were originally determined.
Hydrostatic limits in liquids and solids to 100 kbar
Authors: Piermarini G. J. , Block S. , Barnett J.D.
Published: February 2004

The hydrostatic properties of the materials methanol, isopropyl alcohol, water, sodium chloride, silver chloride, and the binary mixtures pentane-isopentane and methanol-ethanol have been determined in the diamond-anvil pressure cell up to 180 kbar by line-broadening and line-shift measurements of the sharp R1 ruby fluorescence line. A liquid mixture 4 : 1 by volume of methanol : ethanol remains hydrostatic to almost 100 kbar at room temperature. This mixture exceeds the hydrostatic limit of the previous generally accepted fluid, 1 : 1 pentane : isopentane which has a hydrostatic limit of about 70 kbar. Silver chloride and water (ice VII) are better than sodium chloride as pressure-transmitting media, but do not even qualitatively approach hydrostatic conditions much above 70 kbar. The stress sensitivity level of the ruby limits the extent to which slight deviations from hydrostatic conditions can be determined in solid systems and suggests the qualitative nature of the method in characterization of quasihydrostatic states. The equilibrium freezing pressure of methanol at 24°C was redetermined to be 35.8±0.8 kbar.
Recombination luminescence from electron-irradiated Li-diffused Si
Authors: Johnson Eric S. , Compton W. Dale , Noonan J. R. , Streetman B. G.
Published: February 2004

Lithium doping has a dramatic effect on the low-temperature photoluminescence of electron-irradiated Si. In oxygen-lean Si with Li doping, a new irradiation-dependent luminescence band between 0.75 and 1.05 eV is observed, which is dominated by a zero-phonon peak at 1.045 eV. This band is believed to be due to radiative transitions involving a Li-modified divacancy. This band is present also in oxygen-rich, Li-diffused Si and is accompanied by bands previously related to the si-G 15 (K) center and the divacancy. The intensities of the Li-modified divacancy and Si-G 15 (K) center bands are relatively weak in the oxygen-rich material, apparently due to the formation of lithium-oxygen complexes which reduce the concentration of unassociated interstitial Li and O.
Two-carrier model for high field conduction in SiO2
Authors: O'Dwyer J. J.
Published: February 2004

The current mean field strength characteristics are calculated for a special model of an insulator in which low-mobility holes are thermionically emitted from the anode and high-mobility electrons are cold emitted from the cathode. In the general case, the conduction characteristics are both thickness and temperature dependent.
Electrical properties of metal-SiO2-silicon structures under mechanical stress
Authors: Wonsiewicz B. C. , McCaughan Daniel V.
Published: February 2004

The processing of integrated circuits usually introduces mechanical stress into the device structure. Contradictory results and speculations exist in the literature on the effects of such stresses on the electrical properties of the SiO2–Si interface. Results of three series of experiments in which the electrical properties were measured by MOS capacitance-voltage methods are reported. Stress was applied at the SiO2–Si interface by deposition of stressed tungsten films. In the first experiments, the stress at the SiO2–Si interface was varied by deposition techniques and heat treatments. Although several such experiments are reported in the literature, our results demonstrate that such experiments invariably lead to ambiguous results and interpretation. A second series of experiments in which the metallization thickness was varied by planar etching, and a third series in which metallization patterns of widely differing geometries, from 5 to 500 μm were used, separately show conclusively that mechanical stresses in the range encountered in device structures do not affect the electrical properties of the SiO2–Si interface.
Observation of three-photon conductivity in CdS with mode-locked Nd : glass laser pulses
Authors: Jayaraman S. , Lee Chi H.
Published: February 2004

The photoconductivity in CdS single and polycrystals was investigated by using mode-locked Nd : glass laser pulses for excitation and was found to exhibit a power law I2.83±0.2, where I is the peak excitation intensity. The three-photon absorption coefficient estimated from the photoconductivity measurement agreed well within an order of magnitude with the theoretical values.
Composition and irradiation-temperature dependence of the uniaxial anisotropy energy of large-grain iron-nickel alloy thin films
Authors: Williams C. M. , Schindler A. I.
Published: February 2004

The irradiation-temperature dependence of the uniaxial anisotropy energy Ku has been examined for a series of well-stabilized large-grain ([inverted lazy s]0.2 μ) iron-nickel alloy thin films having compositions between 44% Ni and 90% Ni. The uniaxial anisotropy was developed in these films by irradiating at temperatures of 125, 225, 275, 300, 325, and 400 °C, in the presence of a 180-Oe magnetic field applied parallel to the film's easy direction of magnetization. Room-temperature measurements of Ku following the irradiations indicate the development of three types of order: (i) iron-iron pair short-range directional order which is present for all compositions, (ii) NiFe long-range order for films with compositions between 44% Ni and 70% Ni which were irradiated below 400 °C, and (iii) Ni3Fe long-range order for film compositions around 75% Ni. The uniaxial anisotropy energy induced in films irradiated at 400 °C proved to be almost entirely the result of iron-iron pair ordering as shown by the good agreement obtained between the experimental values of Ku and those calculated using the pair-ordering theory. At temperatures below 400 °C, the induced anisotropy was primarily the result of NiFe long-range order for film compositions between 44% Ni and 70% Ni. The results of anisotropy energy measurements for these films indicate the following: (i) the critical temperature for NiFe order Tc is composition dependent and agrees with the values obtained for neutron bulk-irradiated samples; (ii) the NiFe order mechanism may be governed primarily by single vacancy diffusion; and (iii) the maximum value of Ku obtaind below Tc probably depends more on the irradiation rate (flux) than fluence.
Use of electrical conductance measurements in studies of the orientation of microscopic particles in stationary and flowing suspensions
Authors: Dellimore J. W. , Gosling R. G.
Published: February 2004

This paper considers the applicability of theoretical equations for the electrical conductivity of homogeneous suspensions of identical nonconducting spheroids to studies of particle behavior in suspensions of practical interest. Results of particle shape and concentration determinations conform to theory up to volume concentrations of 0.6–0.65. The predicted relationship between particle orientation and suspension resistance is verified experimentally. The method is used to study erythrocyte orientation during blood flow in a tube of rectangular cross section. Results are consistent with observations reported by previous investigators and are in qualitative agreement with the theory of Peterlin and Stuart for the orientation distribution of microscopic spheroidal particles in dilute suspensions undergoing shear flow and subject only to thermal agitation.
Spectroscopy study of copper impurities in silicon
Authors: Chen C.S. , Corelli J.C.
Published: February 2004

Infrared spectroscopy has been used to study copper impurities in irradiated and unirradiated silicon. No Cu-associated bands are observed before or after neutron irradiation of the copper-diffused samples. The presence of Cu impurities in Si does not affect the production of divacancy defects, implying no interaction of Cu with radiation-induced defects.
Image force work function of dielectric layers
Authors: Dionne Gerald F.
Published: February 2004

The classical theory of electric images is employed to calculate the image force work function of a dielectric layer on a conducting substrate. Theoretical results indicate that the work function should decrease with layer thickness and increase with dielectric constant. Correlated experimental data are offered in support of these conclusions.
Filling rates of long liquid-filled capillaries
Authors: Stone J. , Earl H. E.
Published: February 2004

Fused quartz capillaries 700 and 1200 m long and 100 μm in inside diameter have been filled under hydrostatic pressure. It is verified that the rate of filling is governed by Poiseuille's law, which predicts the filled length to be proportional to the square root of the filling time. At a pressure of 270 atm, 250 m was filled in 1 h, 800 m in 10 h, and 1200 m in 21 h. The filling rate cannot be increased significantly from the above values by increasing the pressure because of the increase in the viscosity of the fluid with increasing pressure. Since it requires high pressure to move the liquid in a long capillary, it is apparent that liquid will not flow out of a long capillary that is not under pressure.
Modifications of the theoretical model for a self-pulsing ring laser
Authors: Halford C. E.
Published: February 2004

The theoretical model for a self-pulsing ring laser has been modified by confining the active medium to a length less than the cavity length. Some of the results of this modification are reported in this paper. Also, a more general type of loss has been considered and the results are included.
Dwell times of exploding tungsten wires in air
Authors: Vlastós Antonios E.
Published: February 2004

The paper deals mainly with the voltage dependence of the dwell times of 130-mm-long tungsten wires with diameters of 0.05, 0.10, 0.15, and 0.20 mm. The results of the measurements reported show that tungsten wires have dwell times of only the short type, that the restrikes are always initiated at the exterior of the wires, and that during the dwell times tungsten wires have higher conductivity than copper or constantan wires. At low voltages the dwell times increase with increasing wire diameter. However, above 10 kV the dwell times within the range of experimental error are equal for all the diameters examined. A comparison with the results obtained from exploding copper wires with the same diameter shows that at low voltages the short dwell times of the copper wires are shorter than those of the tungsten wires and that at higher voltages the dwell times of the tungsten wires become much shorter than those of the copper wires, decreasing monotonically with increasing voltage. The special features of the exploding wires during the dwell times and the restrike phase are illustrated by films made by a rotating-mirror streak camera, a camera with a Kerr-cell shutter, and an image-converter camera.
Resistor focusing of the injected electrons in the Astron
Authors: Christofilos N. C. , Langdon A. B. , Porter G. D. , Rensink M. E.
Published: February 2004

The net axial focusing force for a non-neutral cylindrical E layer in various Astron resistor configurations is calculated. There is strong focusing for cases in which there are resistors on the cantilever.
Optical properties of a toroidal electrostatic mirror in its plane of symmetry: application to a cylindrical condenser
Authors: Bolduc Léonard , Baril Marcel
Published: February 2004

This paper is concerned with the evaluation of the optical properties of the portion of a beam of charged particles lying in the plane of symmetry of any toroidal condenser used as an electrostatic mirror. It gives a general treatment that permits the calculation of the optical characteristics and the aberrations when a trajectory and its derivatives relative to the entry energy and angle are known. Results are applied to the case of a cylindrical condenser, resulting in an important extension of the knowledge of its properties. No attention is given to space-charge effects and to the motion off the plane symmetry where the electric field is generally not central anymore.
Deep levels in GaP
Authors: Okuno Yasuo , Suto Ken , Nishizawa Jun-ichi
Published: February 2004

Change of the junction capacitance under the illumination of monochromatic radiation has been observed in GaP n+p junctions. The peaks were observed at 1.8 and 2.4 eV at 77°K. The 1.8 eV peak was attributed to the hole activation from Fe3+ to the valence band. The photoconductivity spectrum and the transient phenomenon of the photoconductivity in p+n junctions and in high-resistivity n-type bulk crystals also showed the presence of the 1.8 eV level due to Fe.
A calculation of magnetic transition temperatures of rare-earth alloys
Authors: Yang Tien Tsai , Robinson Lawrence Baylor
Published: February 2004

A theoretical expression for magnetic transition temperatures of binary rare-earth alloys is proposed based on the similarity between the expressions of spin-disorder resistivity and transition temperatures of pure rare-earth metals. The proposed expression for the magnetic transition temperature for binary rare-earth alloys is kTc (or Tp)=(−3πZ2)/EFΩ2)ΣRn≠0Φ(2KFR) × [x(1−x)Vab2 + xGa2(ga−1)2ja(ja+1)+(1−x)Gb2 (gb−1)2jb(jb+1)], where Φ(2KFR)=(KFR×cosKFR - sinKFR)/(KFR)4 and the other symbols have their usual meaning. The above expression is obtained from considering an equation for spin disorder resistivity given by Dekker. The experimental data of magnetic transition temperatures of Gd–Dy system have been used to test the validity of the proposed equation. The agreement between theory and experiment is reasonably good.
Application of electron-transparent (111) silver platelets as substrates in epitaxial studies
Authors: Snyman H. C. , Olsen G. H.
Published: February 2004

Chemically produced silver platelets were found to serve as ideal substrates for epitaxial experiments. The preparation, cleanliness, and perfection of these platelets are described and the epitaxial growth of iron on silver is discussed as an example. It is shown that iron deposits of average thickness as low as 1 Å may be detected via transmission electron diffraction, provided a sufficiently thin silver platelet is used as a substrate.
Effects of annealing on the carrier concentration of heavily Si-doped GaAs
Authors: Kung J. K. , Spitzer W. G.
Published: February 2004

Isothermal and isochronal annealing measurements were performed on heavily Si-doped GaAs. Infrared reflectivity measurements were used to determine the free-carrier concentration after each annealing stage. A factor of [inverted lazy s]5 decrease in free-carrier concentration was observed as a result of annealing at temperatures as low as 400°C. This annealing effect can be important when fabricating devices using GaAs: Si. Possible explanations of this effect are discussed.
Thermal conductivity of Evanohm in the temperature range 0.4–77 K
Authors: Strom Daniel J. , Linz R. J.
Published: February 2004

The thermal conductivity of an Evanohm rod has been measured from 0.4 to 77 K. From these data the thermal conductivity of fine wires of Evanohm may be approximated.
Internal stresses and resistivity of low-voltage sputtered tungsten films
Authors: Sun R.C. , Tisone T.C. , Cruzan P.D.
Published: February 2004

The continuing development of microelectronic circuits toward greater complexity has stimulated interest in new materials and processes compatible with the currently known silicon device technology. Tungsten has been considered as the first-level conductor for a multilevel structure due to its relatively low electrical resistivity, its thermal expansion coefficient which matches fairly well to that of silicon, its demonstrated good adherence to the dielectrics of interest, and its ability to withstand high-temperature processing. The present work is a part of a study of the dependence of the properties of low-voltage triode sputtered tungsten films upon deposition parameters. The effects on internal stress and resistivity of tungsten films are reported here. Tungsten films have been deposited with thicknesses from 1000 to 15000 Å and with resistivities as low as 8 μω cm (1.55 of the bulk). These films were deposited at 1 μ argon pressure at rates in the range of 50–400 Å/min. The electrical resistivity was observed to increase with increasing deposition rate, decreasing film thickness, and decreasing substrate temperature. The impurity concentration was found to be small by electron microprobe and ion probe techniques and, hence, did not completely account for the observed changes in resistivity. The internal stress was determined by two x-ray methods: (i) precision lattice parameter determination and (ii) a two-exposure technique. In general, depending upon the deposition conditions, tensile or compressive stresses of the order 109−1010 dyn/cm2 were observed. The compressive stress was observed to increase with decreasing film thickness and increasing deposition rate. Increasing the substrate temperature caused the compressive stress to decrease to zero and become tensile. This changeover temperature was observed to be 650°C for a 5000-Å film deposited at 115 Å/min. The observed results are discussed briefly in terms of microstructure changes.
Influence of high concentrations of solute atoms on the critical flow stress of binary alloys. II. Application to silver-, gold-, and copper-based alloys
Authors: Boser O.
Published: February 2004

A previously developed theory of the critical flow stress due to high concentrations of solute atoms is further specified by the calculation of the interaction between solute atoms and dislocations due to a size and modulus difference between solute and matrix atoms. It turns out that the first-order interaction due to the size difference cancels identically. Therefore, only second-order effects are responsible for the critical flow stress due to high concentrations of solute atoms. This is demonstrated by the agreement between the calculated stress and the available experimental data on Ag-, Au-, and Cu-based binary alloys. The length of the dislocation segment that moves as a whole was determined from these data to be about L=3×10−4 cm for all alloys, a value that is in agreement with the assumption that the length of the dislocation segment should be comparable to the distance between pinning points of a Frank-Read source. This long dislocation segment does not allow for thermal activation and therefore is the basis for the temperature independence of the stress component, due to high concentrations of solute atoms.
Grüneisen parameters of germanium-silicon alloy
Authors: Gauster W. B.
Published: February 2004

Using a technique described recently by Gauster, a direct determination of the Grüneisen parameter was carried out for GeSi (80 at.% Si) alloy between 130 and 300 K. The value varied smoothly between 0.57 at 300 K and 0.22 at 130 K. The measured Grüneisen parameter agreed within the experimental error with the values predicted by an elastic continuum model which used the Ge and Si properties as inputs.
Deposition of 1 : 1 Bi–Sb alloy films by steady-state evaporation
Authors: Dale E. B. , Varadarajan B. N.
Published: February 2004

Stoichiometric films of Bi–Sb alloy have been made as a test of the steady-state method for evaporating alloys. X-ray fluorescence analyses of the films show that they have constant composition within analytical error. Some details of the analytical procedure are given.
Plastic deformation of potassium chloride single crystals due to 5-MHz ultrasonic waves
Authors: Schinker Martin G.
Published: February 2004

Long-range movement of Frank-Read source generated dislocation loops, produced by intense longitudinal 5-MHz ultrasonic waves, was observed in potassium chloride single crystals by stress-optical and etching techniques. Dislocation multiplication of individual dislocation sources along particular slip planes was noted. Plastic deformation of KCl crystals by ultrasonic standing waves is explained by the movement and multiplication of dislocations in the antinodal planes in accordance with the models proposed by Frank and Read and Koehler and Orowan. Concentrations of edge dislocations were observed in the nodal planes of the ultrasonic wave in accordance with the low dislocation mobility at a low shear-stress level.