bluuebunny/crossref_metadata_2025 huggingface dataset:
Reflection and Transmission of Electromagnetic Waves by a Moving Dielectric Medium
Authors: Yeh C.
Published: April 2005

The reflection and transmission of electromagnetic waves by a moving dielectric medium are investigated theoretically, and the reflection and transmission coefficients are determined. Two cases of the movement are considered: (a) The dielectric medium moves parallel to the interface. (b) The dielectric medium moves perpendicular to the interface.

Various interesting features concerning the variation of the reflection and transmission coefficients, angles of reflection and transmission, and the frequencies of the reflected and transmitted wave, as a function of the velocity of the moving medium, are discussed.
X-Ray Method for the Determination of the Polarity of SiC Crystals
Authors: Brack Karl
Published: April 2005

The semiconductor SiC is a polar compound. As a consequence the opposite faces of {00.1} wafers have different chemical properties and hence different etch patterns. These differences, however, give no convincing evidence as to which side is the Si side and which is the C side of a SiC single crystal. Theoretically, small differences in x-ray reflection intensities are shown to be expected from opposite crystal faces. By careful crystal surface preparation these differences could experimentally be verified. Thus the proper correlation between the Si or C face and the etch patterns has been established.
Microinstabilities in Transversely Magnetized Semiconductor Plasmas
Authors: Hasegawa Akira
Published: April 2005

Microinstabilities in semiconductor plasmas with dc magnetic and electric fields being applied perpendicular to each other are considered. Two-stream and resistive-type instabilities are discussed. For an example of the typical parameters of InSb, it is shown that a resistive-type growing wave can be excited in the microwave frequency range. The analysis includes the effect of the electron-lattice and hole-lattice scatterings and that of the thermal velocity of the particles involved.
Infrared Properties of 40–60 MeV Electron-Irradiated Germanium
Authors: Becker J. F. , Corelli J. C.
Published: April 2005

The infrared properties of germanium containing low oxygen concentration (<1016 cm−3) and high oxygen concentration (>1017 cm−3) have been studied after irradiation at T≤25°C by 40- to 60-MeV electrons. One cold-temperature irradiation at 125°K was also performed on a high oxygen concentration germanium sample. The germanium samples that were n type initially exhibit p-type infrared properties in the 2- to 8-μ wavelength range after being converted to p type by the irradiation. Germanium containing high oxygen concentration exhibits new vibrational bands in the 9- to 16-μ wavelength range which are associated with oxygen-defect complexes. No radiation-induced bands from 9 to 16 μ are observed in oxygen-free germanium. Detailed isochronal annealing experiments (up to ∼700°K) were performed on all samples. Strong evidence is given which shows that one of the oxygen vibrational bands induced in germanium (at 618 cm−1) appears to be a single oxygen atom plus a vacancy defect which corresponds to the comparable defect found in silicon, namely the silicon A center.
Reflection of Electromagnetic Waves from a Rough Surface
Authors: Kivelson M. G. , Moszkowski S. A.
Published: April 2005

It is shown that in the small-wavelength limit the cross section per unit area for backscattering of electromagnetic waves from a rough reflecting surface is given by dσB/dΩ=½𝒫(ψ), where 𝒫(ψ)=the probability that the normal to the surface makes an angle ψ with respect to a reference surface. This formula was previously stated without proof in a paper by Salpeter and Treiman. For the special case of a Gaussian distribution, this result corrects a formula previously derived by Davies, and agrees with the results of Ruffine.
Effects of Annealing and Silicon Substitution on Audio-Frequency Magnetic Properties of Single-Crystal Yttrium Iron Garnet
Authors: Wickersheim K. A. , Comstock R. L. , Lefever R. A.
Published: April 2005

Audio-frequency hysteresis loops and initial permeabilities obtained from single-crystal yttrium iron garnet cores are presented. The results demonstrate the effects of annealing and silicon-substitution on bulk magnetic properties. It is found that annealing of nominally pure YIG raises substantially the initial permeability and reduces markedly the field required for saturation. Addition of 0.25 wt% SiO2 to the melt from which the garnets are grown yields a material with a strongly frequency-dependent initial permeability.
The Lorentz Field in an Antiferromagnet
Authors: White Robert M.
Published: April 2005

It is shown that in a multiple sublattice spin system the Lorentz field associated with one sublattice exerts a torque on the other sublattices. In the case of uniform precession, this modifies the demagnetization field thereby altering the resonant frequency. It is also shown that spin waves produce a Lorentz field which shifts the spin-wave manifold.
Conduction and Rectification in Anodic Oxide Films
Authors: Vermilyea D. A.
Published: April 2005

Electronic conduction in anodic oxide films of all thicknesses on all metals studied (Ta, Nb, W, Zr, Al) can occur at certain flaws in the films. Flaw conduction usually dominates the behavior of thick films; it is characterized by marked hysteresis and unusual memory and temperature effects. Flaw conduction is shown to occur by at least two mechanisms: one the opening of physical holes and the other involving some kind of electronic junction. Conduction in the bulk of the film dominates on thin films of Ta2O5, Nb2O5, and WO3. Such conduction is not entirely uniform, and depends strongly on formation conditions, film thickness, temperature, and film history. The mechanism of this bulk conduction appears to involve primarily electron injection into an insulator containing traps; rectification occurs when the contacts produce an asymmetric barrier.
Striation Production during Electrical Breakdown in Hydrogen
Authors: Neusel R. H. , Silver M.
Published: April 2005

Striations, with an average lifetime of about 5 μsec, have been observed during the initial phase of electrical breakdown in H2, at pressures ranging from 3 to 50 Torr, and with 2.5 kV applied across a 5-mm gap. The striations were observed to propagate towards the cathode at about 104 cm/sec, but the rate of advance of the appearance point of the striations was at least four times faster and towards the anode.
Pressure-Dependent Breakdown Potentials in Penning Mixtures
Authors: Chanin Lorne M. , Rork G. D.
Published: April 2005

Measurements have been made of the primary and secondary electron ionization coefficients in neon-hydrogen, helium-hydrogen, and neon-argon mixtures using the Townsend technique. In these experiments, measurements have been conducted over a considerable range of pressures at the E/p0 value corresponding to the maximum of the Penning effect and for the optimum concentrations. Examination of the prebreakdown current growth indicated at fixed E/p0 a pressure-dependent breakdown potential. Measurements of the primary coefficient as a function of pressure showed no significant pressure variation. Measurements of the secondary ionization coefficient, however, indicated that γ decreased with increasing pressure consistent with the observed breakdown potential variation.
Theory of a Pressure-Tuned Lead Salt Laser
Authors: Pratt G. W. , Ripper J. E.
Published: April 2005

The frequency and polarization dependence on applied stress of the output radiation of PbTe and PbSe diode lasers is discussed. Because the energy gap decreases with applied pressure, the output wavelength can be tuned over a wide range. It is estimated that the emission from a PbSe diode can be tuned continuously from its unstressed value of 8.5 μ by a 100 uniaxial stress to 9.6 μ at 5×103 atm and to 10.5 μ at 104 atm. It is proposed that sound waves can be used to frequency-modulate a laser diode.
Ionization and Recombination in Cesium-Seeded Plasmas near Thermal Equilibrium
Authors: Harris L. P.
Published: April 2005

Measurements have been completed of electron-density relaxation in cesium-seeded plasmas perturbed from thermal equilibrium at temperatures in the 1500° to 2000°K range. The gases consisted of 0.1 to 20 Torr Cs vapor in atmospheric pressure argon or helium. Electron densities ranged over 1.9×1011 to 3.8×1013 cm−3 and relaxation times over 30×10−6 to 50×10−3 sec. The results indicate that charge production and loss are dominated by the atomic-ion process Cs+e+3.89 eV↔Cs++2e at the higher temperatures, and by the molecular-ion process Cs+Cs+2.82 eV↔Cs2++e at the lower temperatures and higher cesium pressures. At the lower temperatures and lower cesium pressures the dominant process is ambipolar diffusion. The results obtained when the atomic-ion process dominates agree well with calculations based on the equilibrium properties of the gas and recent theory for two-electron, three-body recombination. The rate of the molecular-ion process corresponds to a two-body recombination coefficient of approximately 1×10−8 cm3/sec at temperatures of 1250° to 1400°C, a value small relative to that derived from earlier experiments. All evidence indicates that, despite their numerical preponderance, the argon and helium atoms play no significant roles beyond those of thermal bath and diffusion barrier.
Maxwell-Wagner Polarization in Sintered Compacts of Ferric Oxide
Authors: Hilborn R. B.
Published: April 2005

A method is presented for the analysis of relaxation spectra resulting from Maxwell-Wagner interfacial polarization in sintered oxide compacts. Using a multilayer model to represent ferric oxide pellets, containing heterogeneities induced by the sintering process, a distribution function of the relaxation times is derived which, when applied to the Maxwell-Wagner equation for a simple two-layer capacitor, gives an equation empirically found to describe the dielectric properties of the samples. Data are presented to show the close parallel between the distribution of relaxation times, predicted by the distribution function, and the distribution of resistivities found to be present in the samples from dc measurements. Comparisons are made between the data predicted by the analytical equations and those obtained from experimental methods. It is concluded that the use of a distribution function of the relaxation times for the analysis of the relaxation spectra is physically justifiable and that the multilayer model in conjunction with an asymmetric distribution function is capable of accurately describing the relaxation spectra observed in sintered compacts of α-Fe2O3.
Analysis of the Nondegenerate Parallel Pumping of Magnetoelastic Waves in Ferromagnets
Authors: Comstock R. L. , Hansen Eldon
Published: April 2005

An analysis is presented of the parametric coupling of two standing magnetoelastic waves with different frequencies (nondegenerate) by an rf magnetic field parallel to the saturating dc magnetic field in a ferromagnet. The parametrically excited waves are located on separate branches of the magnetoelastic spectrum. The nondegenerate instability threshold is compared to thresholds for competing degenerate instabilities and conditions are derived under which the nondegenerate instability is favored.
Magnetic Properties of InAs Diode Electroluminescence
Authors: Galeener F. L. , Melngailis I. , Wright G. B. , Rediker R. H.
Published: April 2005

Spontaneous and laser electroluminescence of InAs diodes have been studied in magnetic fields up to 109 kG. The peak of the emitted energy shifts linearly with magnetic fields above 20 kG at a rate which depends on the carrier concentration of the n-type base material. If the energy shift is described as ΔE=12ℏeH/m*c, the value of m* is the same as that measured at the Fermi level in bulk n-type material. The emission from one laser diode exhibited a splitting which corresponds to a g factor of about 7 for the electron. Evidence was obtained that the laser threshold current is reduced by the component of magnetic field perpendicular to the junction current.
Demagnetizing Field in Nonellipsoidal Bodies
Authors: Joseph R. I. , Schlömann E.
Published: April 2005

A general method for calculating the (nonuniform) demagnetizing field in ferromagnetic bodies of arbitrary shape is described. The theory is based upon the assumption that the magnitude of the magnetization vector is constant throughout the sample and that its direction coincides with the direction of the local magnetic field at any point within the sample. The total magnetic field is expressed as a series of ascending powers in M/H0, where M is the saturation magnetization and H0 the applied magnetic field. The first term of this series expansion (first-order theory) gives the demagnetizing field for very large applied fields, i.e., for a uniformly magnetized sample. The higher-order corrections (we consider in detail only the first correction term; second-order theory) take account of the fact that the sample is not in general uniformly magnetized. The general theory has been applied to rectangular slabs and circular cylinders. The first-order demagnetizing field has been calculated for rectangular slabs and circular cylinders of arbitrary dimensions. Our discussion of the second-order theory is restricted to the semi-infinite slab and the semi-infinite circular cylinder. For the semi-infinite slab the variation of the second-order demagnetizing field along the central symmetry axis and across the endface have been calculated. In cases of practical interest (spin-wave propagation experiments in YIG at 3 Gc/sec and applied magnetic field of about 1400 Oe), the second-order correction to the demagnetizing factor is approximately 20% of the first-order contribution.
Dynamical Theory of Thermoplastic Deformation
Authors: Budd Herbert F.
Published: April 2005

A theoretical analysis of the surface deformation of an electrically charged thermoplastic film is given. Simple expressions are derived which relate the spatial harmonics characterizing the deformation and growth rate of the deformation with the surface charge density, film thickness, and material constants of the thermoplastic. The necessary conditions for the occurrence of the deformation are discussed.
Microwave Properties of a Calcium-Vanadium-Bismuth Garnet
Authors: Nilsen W. G. , Spencer E. G.
Published: April 2005

The microwave properties of single crystals of the garnet {Ca2.5Bi0.5}[Fe2](Fe1.75V1.25)O12 were measured from 4.2°K to room temperature. This garnet is of particular interest in applications since it is free of expensive rare-earth and yttrium ions which require extensive purification. The linewidth is quite small, varying from 1.5 to 9 Oe, depending on temperature and orientation. Considering the small saturation magnetization of this garnet (4πM=610 G) the magnetic anisotropy field is unusually low at 4.2°K, namely about 275 Oe along the easy axis of magnetization. The calcium-vanadium-bismuth garnets have been found to be particularly useful in isolators for traveling-wave masers. Because of the unique combinations of low anisotropy and low magnetization, operation can be obtained at lower frequencies in the frequency-magnetic field region near g=2 than for pure or substituted yttrium iron garnet. The characteristics of such an isolator operating at 1750 Mc/sec and 300 Oe are described.
Elastic Moduli of Quartz versus Hydrostatic Pressure at 25° and − 195.8°C
Authors: McSkimin H. J. , Andreatch P. , Thurston R. N.
Published: April 2005

Ultrasonic wave velocities in single-crystal quartz have been measured as a function of temperature and pressure by means of a pulse superposition method described in J. Acoust. Soc. Am. 33, 12 (1961). In order to make good use of all the experimental data, a set of ``adjusted'' velocities and initial pressure derivatives was obtained which satisfies all the cross-checks exactly, while minimizing a weighted sum of the squares of the adjustments from the measured values. These adjusted values were then used to calculate the elastic moduli as functions of temperature and pressure. Values of ``zero-field'' moduli at zero pressure and the initial pressure derivatives determined in this way are shown below. T=25∘CT=−195.8∘CValue at p=0PressureValue at p=0PressureModulus(1011 dyn/cm2)derivative(1011 dyn/cm2)derivativec118.6803.288.7263.40c12=c11−2c660.7048.660.9907.40c131.1915.971.3025.41c14−1.8041.93−1.7732.00c3310.57510.8410.91910.26c445.8202.665.9721.77c663.988−2.693.868−2.00
Sputtering Yields of Alkali Halide Single Crystals Bombarded by 2- to 10-keV Ions
Authors: Navinšek B.
Published: April 2005

Fresh (100) cleavage faces of sodium chloride, potassium chloride, potassium bromide, and lithium fluoride single crystals were bombarded by Ar+ ions under normal incidence. Sputtering yields for these crystals in the energy range from 2 to 10 keV are between 0.30 and 2.15 atoms per ion. The ion bombardment apparatus and experimental conditions are briefly described.
Structure and Oxidation of Thin Gold-Nickel Alloy Films
Authors: Khan I. H. , Francombe M. H.
Published: April 2005

The structure and oxidation of thin alloy films of composition Au-15 at.% Ni have been investigated by means of x-ray and electron diffraction, and the oxide growth rate determined by measuring changes in the electrical resistivity of the films during oxidation. The films are prepared by sputtering and, even at low substrate temperatures, comprise single-phase homogeneous structures. Oxidation in the temperature range 250°–310°C shows a two-stage logarithmic growth rate (or resistivity change) with time similar to that observed for Ni, Cu, and Fe. This behavior is consistent with the formation of oxide only at the alloy film surface, and can be interpreted qualitatively in terms of the electron-transfer model proposed by Uhlig et al., for the oxidation of pure Ni.

Epitaxial alloy films with (001) and (111) orientation are produced by sputtering onto the cleaved surfaces of NaCl and mica at about 400°C. On annealing these films at and above 500°C, pre-precipitation effects are observed in the electron-diffraction patterns. These are associated with the formation, in succession, of the superlattice structures, NiAu3 and NiAu. True precipitation of Ni-rich alloy occurs at temperatures above 600°C.

Oxidation of epitaxial films of the disordered alloy at temperatures below 250°C results in the growth of poorly crystallized, non-oriented NiO. At 280°C both non-oriented and also three differently oriented oxide products, are formed, the NiO orientations corresponding to those reported by Collins and Heavens for oxide growth on Ni films. At 400°C only oxide orientations parallel to the metal film are detected.
Piezoelectric Current from Shock-Loaded Quartz—A Submicrosecond Stress Gauge
Authors: Graham R. A. , Neilson F. W. , Benedick W. B.
Published: April 2005

Current from X-cut quartz disks may be used to detect stress-time profiles induced by shock loading. The current amplitude and its time dependence are functions of the dielectric, piezoelectric, and mechanical properties of quartz under shock-loading conditions. The results of an extensive experimental study of the current from shock-loaded quartz disks are reported for shock stress up to 50 kbar. The experiment is performed by impacting precisely aligned X-cut quartz disks upon each other at various measured velocities and observing the current in one of the disks during the first wave transit. Within the low signal range, the piezoelectric stress constant e11 is found to be 0.174 C-m−2. The coefficient relating current jump to stress jump in one-dimensional strain is found to be 2.04×10−8 C-cm−2-kbar−1 up to 6 kbar and 2.15×10−8 C-cm−2-kbar−1 from 9 to 18 kbar. The wave velocity was determined to be constant to 25 kbar. The observed current waveform could be fully interpreted in terms of rate-independent properties. Determinations of distortions to the current from apparently minor deviations from one-dimensional conditions were also made.
New Oxy-Hydrogen Burner for Flame Fusion
Authors: Adamski Joseph A.
Published: April 2005

A three-tube postmix burner using oxygen and hydrogen has been developed, enabling large-diameter single crystals to be grown. The design of this burner permits one to grow many different types of materials without changing burners (Verneuil to tri-Cone), and greatly reduces gas turbulence. Comments on growth of rutile, strontium titanate, nickel oxide, sapphire, and spinel are included.
Charge Growth Equation for Belts of Insulating Materials Passing over Grounded Rollers
Authors: Cunningham R. G. , Coburn T. J.
Published: April 2005

The magnitude of the electrostatic charge density on an insulating belt of photographic film increases as the belt passes repeatedly over a set of grounded metal rollers. The charge density q asymptotically approaches an equilibrium value qe according to the relation q = qe (1 − e−n/τ), where n is the number of roller passages and τ is an arbitrary constant. An equivalent circuit which describes this behavior is presented. The circuit elements are an electromotive force, a contact resistance, a leakage resistance, and a capacitance between the belt and the roller. The physical equivalents of these elements and the possibility of their measurement are discussed.
High-Frequency Behavior of the Surface-Wave Helicon Instability
Authors: Saunders L. M. , Baraff G. A. , Buchsbaum S. J.
Published: April 2005

The surface-wave instability in helicon wave propagation analyzed by Baraff and Buchsbaum is reinvestigated here for the purpose of extending the analysis to values of ωτ greater than unity. We find that although collisions are essential for the mechanism of instability, the formulas and analysis of Baraff and Buchsbaum, derived for ωτ«1, are unchanged until ωτ exceeds some large value ω0τ. This value ω0τ is typically much greater than unity. At higher frequencies the surface wave penetrates from one boundary to the next and some of the Baraff-Buchsbaum approximations start to lose validity.
Surface-Wave Instability in Helicon Propagation. II: Effect of Collisional Losses
Authors: Wallace R. N. , Baraff G. A.
Published: April 2005

The surface-wave instability analyzed by Baraff and Buchsbaum in the limit of infinite ωcτ is investigated here for ωcτ large but finite. In the previous analysis, the carrier drift velocity required to establish the instability was found to be proportional to (K1−K2), the effective dielectric mismatch across the interface at which the surface wave was excited. Here we find that with ωcτ large but finite, this threshold velocity is increased by an amount proportional to (ωcτ)−1 and inversely proportional to (K1−K2). For a given value of ωcτ there thus exists an optimum choice of (K1−K2) which minimizes the required threshold velocity. These new results can be obtained from heuristic arguments which do not require the calculation of field components beyond lowest nonvanishing order in (ωcτ)−1. The heuristic arguments are here justified rigorously for the physically interesting case of small (K1−K2).
Snoek Atmosphere Dislocation Pinning in Tantalum
Authors: Baker G. S.
Published: April 2005

Snoek pinning of dislocations due to oxygen in tantalum was investigated using internal friction and simultaneous deformation techniques. The magnitudes of the pinning in the two oxygen concentrations used (5 ppm and 100 ppm) were found to be approximately 20 kg/cm2 and 150 kg/cm2, respectively. This shows that Snoek pinning can contribute a significant fraction of the yield stress in material with high concentrations of dissolved interstitials.
Molybdenum-Silicon Schottky Barrier
Authors: Kano Gota , Inoue Morio , Matsuno Jin-ichi , Takayanagi Shigetoshi
Published: April 2005

An ideal metal-semiconductor Schottky barrier contact was made by chemically depositing thin films of molybdenum on n-type silicon by the hydrogen reduction of molybdenum pentachloride at temperatures between 390°C and 500°C. Current-voltage, capacity-voltage, and photoelectric measurements were used to investigate the characteristics of molybdenum-silicon diodes thus produced. The junction is shown to be very close to the ideal Schottky barrier with the barrier height measured with respect to the Fermi energy of 0.57±0.02 eV.
Laser Amplifier Noise at 3.5 Microns in Helium-Xenon
Authors: Klüver J. W.
Published: April 2005

The noise added to the amplified signal in laser amplifiers results from spontaneous emission in the laser medium. A measurement of the intensity of the spontaneous emission noise has been performed at the high-gain 3.508-μ line in a dc-excited He-Xe discharge. Measurements were made with the laser amplifier operating under normal low-level signal conditions as well as under high-level, saturated conditions. It is found that the measured values of the noise power agree closely with the expressions derived for a four-level excitation system using a plane wave propagation model. The low-level measurement yields a population inversion of 2.6±0.3. For an amplifier with an unsaturated gain of 17 dB and a saturated gain of 1 dB, the increase in the noise output power is only 7 dB over that of an equivalent unsaturated 1-dB amplifier. The measurement of the noise power under saturation gave a ratio of the saturated to the unsaturated upper level population of 0.4. The measurements indicate that the 3.508-μ line has good noise properties. The experiments and the theoretical analysis apply to a one-dimensional geometry in which variations in the transverse direction are negligible.
Variation of the Gain Factor of GaAs Lasers with Photon and Current Densities
Authors: Nannichi Yasuo
Published: April 2005

The variation of the gain factor with the threshold current was studied in two cases, viz., (1) a reflective film was applied on one end of a GaAs laser, and (2) antireflective films were applied on both ends of the laser. In (1) the threshold current is reduced to one third as compared with the case in which no film is applied. The gain factor increases 30%. In (2) the threshold current becomes eleven times greater and the gain factor is reduced to one fourth.

These phenomena were analyzed in the light of spontaneous and stimulated lifetime of electrons in the p region. A formula was obtained giving the gain factor as a function of the density of photons and of current. When the current is constant, the gain factor is inversely proportional to (P+1), where P is the density of photons. At the threshold current the gain factor is inversely proportional to the sum of quasi-Fermi levels, Fn and Fp.

The saturation effect of a light amplifier at a fixed current observed by Crowe and Craig and also the variation of the gain factor with the threshold current can be calculated by this formula.
Temperature-Modulated Optical Absorption in Semiconductors
Authors: Berglund C. N.
Published: April 2005

Temperature-modulated optical absorption measurements on Si, GaAs, CdS, and KTaO3 near the absorption edges are described and interpreted. These measurements show that the experiment is a simple and accurate method of measuring the band-gap energy of semiconductors, and of determining whether the gap is direct or indirect. Information is also obtained on phonon-assisted absorption mechanisms near the band edge and some phonon energies can be deduced. The measurements on Si and CdS verify previous interpretations of the band edge based on optical absorption, and the results from GaAs are nearly identical to those obtained from the electric field modulated absorption experiment. The measurements on KTaO3 indicate that this material has an indirect gap with an energy of 3.45 eV.
Depletion Capacitance and Diffusion Potential of Gallium Phosphide Schottky-Barrier Diodes
Authors: Cowley A. M.
Published: April 2005

The diffusion potential VBO and the intercept V0 of the 1/C2 vs bias plots for n-type GaP-metal Schottky-Barrier diodes have been measured. Photoresponse measurements indicate that VBO is not sensitive to the thickness δ of the interfacial separation between the GaP and the metal; V0 is observed to increase rapidly with δ. The 1/C2 plots are linear in all cases, with slopes independent of V0. The values for the donor density ND, calculated in the usual way from slopes of the 1/C2 plots, seem to agree within experimental error with ND calculated from the resistivity of the GaP.

Several models are proposed for the metal-interfacial-layer-semiconductor system in order to explain this behavior. The GaP-metal diodes are shown to be best characterized by a model which includes a bias-dependent charge in surface states at the semiconductor surface.
Attenuation Length Measurements of Photoexcited Electrons in CuBr Films
Authors: Pong William
Published: April 2005

The attenuation length of photoexcited electrons in evaporated layers of CuBr was estimated by measuring the photoemission yield as a function of thickness. The attenuation length was found to be less than the optical absorption depth at photon energies between 8 and 11 eV. At hν=9.7 eV, the attenuation length is approximately 51 Å.
Transient Spin-Wave Buildup in Ferrites
Authors: Harker K. J. , Shaw H. J.
Published: April 2005

The equations of motion for spin waves in a ferrite, together with the equations for the uniform mode, have been numerically integrated for the case in which the ferrite is spherical in shape and subjected to an applied magnetic field which rises linearly in time. The equations for the uniform mode are completely general and allow for arbitrary amplitude of the mode, so that parametric couplings which lead to spin-wave instabilities of various orders are accounted for, including the ordinary first-order and second-order spin-wave instabilities. The spin-wave equations are solved to first order in the spin-wave amplitudes.

The equations have been solved under the conditions of a linearly rising magnetic field having arbitrary rate of rise, together with a dc applied magnetic field of arbitrary magnitude, and for arbitrary angle between the orientations of the rising and dc fields. Assuming that spin waves are initially excited to thermal amplitudes, a numerical integration is performed over k space to find the aggregate spin-wave growth as a function of time, and the energy in the uniform mode as a function of time in the presence of the amplified spin waves. These results define the conditions under which useful transient devices can be operated for the generation of microwave energy in pulsed magnetic fields, to take advantage of the large rf magnetization available in ferrites when operated beyond the usual limiting values of the uniform mode which apply under steady-state operation.
Mössbauer Study of the Structure and Decomposition of Wustite
Authors: Shechter Hanan , Hillman Peter , Ron Moshe
Published: April 2005

A series of Mössbauer, x-ray, and magnetic measurements has been made on wustite (Fe1−xO). The main new results are:

(a) The dependence of the Mössbauer quadrupole splitting on heat treatment is very similar to that of the atomic constant, confirming Hoffman's conclusions on the variation of x.

(b) The Zeeman Mössbauer lines of untreated wustite below the Curie temperature are completely smeared out; for a sample treated so as to give minimum quadrupole splitting (minimum x) these lines appear.

(c) In a heat-treated sample a Zeeman splitting in the Mössbauer spectrum is observed well above the bulk wustite Curie temperature. This is interpreted as the imposition by the magnetic decomposition products of a magnetic ordering on the otherwise paramagnetic residual wustite with which they are in intimate contact.
Power Flow in Plasma-Filled Waveguides
Authors: Bevc Vladislav
Published: April 2005

The power flow of two types of cyclotron modes propagating in a waveguide filled with a cold collisionless axially magnetized plasma is studied as a function of the location of the point of operation on the Brillouin (ω-β) diagram. Dynamic analysis is used throughout. Partition of the total power flow corresponding to E, H, and EH power is examined and compared with results obtained by the quasistatic approximation in the domain of its presumed validity. The inadequacy of the quasistatic approximation for the analysis of the power flow, and hence the field patterns, is shown.

New properties of cyclotron and plasmaguide modes obtained from the analysis are presented. A possible explanation is offered for the lack of published experimental observation of cyclotron modes in the superluminous phase velocity region.
Carrier Recombination and Trapping Effects in Transient Photoconductive Decay Measurements
Authors: Streetman B. G.
Published: April 2005

A discussion of recombination and trapping kinetics is presented from the point of view of application to the analysis of transient photoconductive decay measurements in semiconductors. The transient solution is reviewed for the case of recombination in a single level, and the limiting approximations are presented for the case of n-type material. The role of minority carrier trapping in transient measurements is discussed, along with the effect of recombination in the trapping center. It is found that trapping effects can be treated as a special case in the recombination equations. Separation of the recombination and trapping effects in various temperature ranges is discussed.
Recombination and Trapping in 60Co Gamma-Irradiated n-Type Germanium
Authors: Streetman B. G.
Published: April 2005

Measurements of carrier lifetime from 110° to 330°K have been made on samples of Sb- and As-doped Ge after irradiation at 77°K and subsequent isochronal annealing. A recombination level near the center of the band gap and a trapping level were introduced by the irradiation, and a new trap was created by the anneal in each case. The recombination centers constituted a small fraction of the total defect density. Energy-level positions and capture cross sections are presented for the observed levels. It is found that the trapping levels exhibit a multiple negative charge at low temperatures, and one of the traps is tentatively associated with the Sb-divacancy complex. The annealing stages are compared with those observed in the investigation of other properties, and several stages are found to resemble those resulting from the formation and breakup of composite defects containing oxygen.
Direct 2T1−2E Phonon Relaxation in Ruby and Its Effect Upon R-Line Breadth
Authors: Calviello Joseph A. , Fisher Edward W. , Heller Zindel H.
Published: April 2005

Fluorescence spectroscopy and R-line excitation measurements have been made on ruby samples at 4°K. These demonstrate the existence of a direct relaxation process between the 2T1 and 2E levels—possibly by emission of a phonon into a mode affecting the trigonal component of the chromium ion site symmetry. It is shown that this process contributes a substantial part to the temperature-dependent R-line breadth in the range 100°–500°K.
Theoretical Expression for the Noise Equivalent Power of Pyroelectric Detectors
Authors: Burdick Glenn A. , Arnold Roy T.
Published: April 2005

An equivalent circuit appropriate for pyroelectric materials is derived without assuming a unidirectional polarization vector. This circuit is used to obtain a theoretical expression for the noise equivalent power (NEP) for detectors using pyroelectric sensing elements. It is found that a good figure of merit for pyroelectric materials is given by Fp=p/[Cpρ(εr′ tanδ)½]. It is shown that the resulting expression for NEP is consistent with experimental results as measured in this laboratory.
High-Voltage Pulse Characteristics of Superconducting Transmission Lines
Authors: Cummings A. J. , Wilson A. R.
Published: April 2005

This paper describes results of high-voltage pulse tests on subminiature, superconducting coaxial delay lines. The results show these cables are capable of transmitting 15-kV, 4.0-μsec-long pulses of nanosecond risetimes. The cables were fabricated from both pure and alloyed metals.
Dislocation Energies and the Concept of Line Tension
Authors: Hirth J. P. , Jo/ssang T. , Lothe J.
Published: April 2005

The concept of a dislocation line tension is discussed and explicit expressions for the total energy of various dislocation configurations in different orientations are given. Based on these energy calculations, it is found that for all cases of practical interest (bow-out segment L≦105b) there is a significant (>25%) difference between the results as obtained from the simplest version of line tension encountered in the literature and the method of the present paper. The difference amounts to as much as a factor of two for a straight-edge dislocation with L=103b.
Effect of Coherent Radiation on the Stability of a Crossed-Field Electron Beam
Authors: Levy Richard H.
Published: April 2005

It has been suggested that a toroidal space vehicle might be raised to a very high positive potential relative to the surrounding space by causing a stable crossed field electron beam to circulate around its outer surface. In this arrangement the electric field exists only between the space vehicle and the electron beam; the magnetic field is imposed by coils within the space vehicle. For the case of very low electron density it has been shown that such a beam can be stabilized against the diocotron (slipping stream) instability by being made sufficiently thick. The stability against coherent radiative perturbations of such a thick beam is studied under the following simplifying assumptions: (a) the geometry is taken as infinite cylindrical; (b) the ratio of all frequencies in the problem to the electron cyclotron frequency is negligible; (c) no perturbation electric fields along the magnetic field lines; (d) on the basis of an analogy, but without direct proof, certain continuous spectra of real eigenvalues occurring in the problem are unimportant; (e) the electrons are cold, and (f) the outer boundary of the ``space vehicle,'' i.e., the cylinder, is perfectly conducting. It is concluded that if there is a gap between the inner edge of the beam and the cylinder, one unstable mode is present for each azimuthal mode number ℓ≥1. It is interesting that this unstable mode represents a radiation directly into space without the assistance of either waveguides or antennas.
Further Considerations on a Theory of Superlinearity in CdS and Related Materials
Authors: Dussel Gustavo A. , Bube Richard H.
Published: April 2005

A theory of superlinearity by Cardon and Bube is extended by considering the effect of a high density of shallow traps, either discrete or with a quasiexponential distribution. New conditions for the breakpoints of superlinearity are introduced. These new conditions allow the explanation of several features of superlinearity in sintered layers, including the ``anomalous'' observation of lifetime decrease above the superlinear region, as described in investigations on CdSe by Stupp. A possible relationship between such trap distributions and an apparent decrease in sensitizing center hole ionization energy in highly impure single crystals of CdS is suggested. A summary of all the basic superlinearity conditions is given, with principal emphasis on the physics of the involved mechanisms.
Current from a Shock-Loaded Short-Circuited Ferroelectric Ceramic Disk
Authors: Halpin W. J.
Published: April 2005

Thin circular disks of polarized ferroelectric ceramics were equipped with electrodes on their faces, and the electrodes were connected by a short circuit. Each disk was traversed by a stress wave, and the resulting current pulse through the short circuit was measured. The stress wave was generated by impact and made to propagate along the disk axis in a direction opposite to that of polarization. Current-pulse data are presented from tests with PZT 95/5, both normally sintered and hot-pressed, and with PSZT 68/7 for impact stresses ranging from a few to several tens of kilobars. Over this range of stress both the shape of the current pulse and its time integral are found to be strongly stress dependent. It is concluded that this behavior results from the combined effects of stress on (1) remanent polarization, (2) polarizability, and (3) conductivity of the ferroelectric material enveloped by the wave. In a narrow range of stress where remanent polarization is reduced to near zero and where conductivity is negligible, the observed behavior can be adequately described by means of a mathematical model which is developed. The model includes the effect of stress wavefront tilt which occurs in impact experiments to an extent that influences significantly the character of the current pulse. Some conclusions are drawn about permittivity of shock-loaded ferroelectrics and the extent to which remanent polarization is affected by the rapidly applied large electric fields which accompany the process of current production.
Observation of Dislocations in V3Si Single Crystals
Authors: Levinstein H. J. , Greiner E. S. , Mason H.
Published: April 2005

An etch-pitting solution which causes etch pits at the point of intersection of dislocations with the (100) and (111) surfaces of V3Si single crystals is described. The effect of second-phase particles imbedded in the single-crystal matrix on the density and distribution of the dislocations is discussed. The observation of the dislocation arrangements suggest that the slip system in V3Si is {100} 〈001〉.
Kilocycle-Range Dislocation Damping in Magnesium Oxide
Authors: Southgate P. D. , Mendelson K. S. , DePerro P. L.
Published: April 2005

Measurements of temperature, frequency, and amplitude dependence of dislocation damping in plastically deformed MgO have been made in the kilocycle range. The low-amplitude damping shows a broad maximum around 150°C, with little variation below room temperature down to 78°K. The damping decreases slightly with increasing frequency and the maximum moves to a slightly higher temperature. At strain amplitudes of greater than about 2×10−6 the damping increases steadily. The excess damping does not give a straight Granato-Lücke plot; it usually gives a relatively straight line of slope 0.8 on a log δ vs log ε plot. The amplitude-dependent damping varies more strongly with temperature than the low-amplitude damping. Annealing at temperatures between 350°C and 650°C causes a steady decrease of damping which may be associated with a process having an activation energy of 2.0 to 2.6 eV. A composite annealing curve, obtained from curves taken at different temperatures, yields a damping which varies as (annealing time)−0.4 over many decades of time. Varying concentrations of many impurities, including iron, seem to have little effect on the behavior, but the introduction of 0.05 at.% chromium reduces temperature dependence and amplitude dependence and introduces a further process of lower activation energy in the early stages of annealing. The results reported here cannot readily be interpreted in terms of the usual theories of dislocation damping.
Lattice Constants of Ultrapure Phenanthrene
Authors: Peters E. T. , Armington Alton F. , Rubin Bernard
Published: April 2005

Ultrahigh-purity phenanthrene has been prepared by multiple zone-refining. To determine if a resistivity anomaly observed at 68°C is associated with a polymorphic transformation, x-ray diffraction scans were made at 26° and 84°C. There is no evidence for a polymorphic transformation over this temperature range, although anisotropic behavior was noted for the thermal expansion coefficients. Precision lattice constants were determined for the monoclinic cell of phenanthrene at 26°C; these are a0=8.4744 Å, b0=6.1720 Å, c0=9.4805 Å, β=98° 01′.
Alloy Films of PbTexSe1−x
Authors: Bis R. F. , Zemel J. N.
Published: April 2005

Thin single-crystal, single-phase films of PbTexSe1−x covering the entire composition range have been prepared by vapor deposition on heated NaCl substrates. Resistivity and Hall effect data at room temperature indicate that the carriers are electrons and that their concentration in these films is in the 1018 cm−3 range. The Hall mobility at room temperature falls in the range 350–800 cm2/V·sec.
Indirect Observation of Antiferromagnetic Domains by Linear Magnetostriction
Authors: Scott R. A. M. , Anderson J. C.
Published: April 2005

This paper reports the annealing and switching of purely antiferromagnetic domains in αFe2O3 as identified by measurements of the coefficients of linear magnetostriction in complete agreement with the predictions of magnetic symmetry. The domain state was found to follow a hysteresis reversal loop caused probably by domain pinning centers within the crystal. The linear magnetostriction coefficients were virtually independent of temperature in the range 77° to 220°K. Magnetostriction also revealed a field-induced reduction of the magnetic transition temperature, this being related to the relative thermodynamic potentials of the two phases. This reduction explains the unusually large measured strains close to the transition in terms of the volume changes resulting from the magnetic transition.
Influence of Adsorbed Gas on Surface Diffusion and Nucleation
Authors: Melmed Allan J.
Published: April 2005

Experiments with the field-electron emission microscope show that residual gas pressures as low as 2×10−8 Torr increase the density of nucleation of copper on tungsten compared with the nucleation density at 4×10−10 Torr ambient pressure. The effect of adsorbed oxygen and nitrogen on the mobility of copper on tungsten depends on the relative amounts of gas and copper and on the local substrate crystallography. Generally stated, they increase the activation energy for surface diffusion.
Optical Properties of Indium Oxide
Authors: Weiher R. L. , Ley R. P.
Published: April 2005

In an investigation of the fundamental optical absorption edge of indium oxide at room temperature, transitions identified as direct-allowed have been observed with an energy gap (probably at k=0) of 3.75 eV. Indirect-forbidden transitions have also been observed with an energy gap of 2.619 eV and an assisting phonon of 0.069 eV. It is proposed that the minimum of the conduction band is at k=0 and the maximum of the valence band is at k≠0.
Hall Coefficient Behavior and the Second Valence Band in Lead Telluride
Authors: Allgaier R. S. , Houston B. B.
Published: April 2005

Measurements of the temperature dependence of the Hall coefficient are presented for samples of p-type PbTe having carrier concentrations between 3×1017 and 1×1020 cm−3. As the temperature increases, the Hall coefficient for any given carrier concentration at first remains at the constant value RL and then increases steadily at higher temperatures. As the carrier concentration increases from the lowest to the highest values studied, the Hall ratio R295°/RL increases smoothly from about 1.1 to 2.5. The data are analyzed in terms of a simple two-valence-band model. The results indicate that the energy separation between the two band edges is about 0.14 eV at 0°K, and that carriers in the second band have a heavy mass and low mobility relative to those in the first. The data also suggest that there are no carriers in the second band in the liquid-helium temperature range, even at the highest carrier concentration. This requires that the first valence band be strongly nonparabolic.