bluuebunny/crossref_metadata_2025 huggingface dataset:
Superconductivity, cohesive energy density, and electron-atom ratio in metals
Authors: England Christopher , Lawson D. David , Hrubes J. Dana
Published: February 2003

It is shown that superconductivity above 8 °K occurs in alloys and metallic compounds within relatively narrow regions of cohesive energy density with a sharp peak which includes Nb3Ge, SiV3, Nb3Ga, and NbN. When cross correlated with the electron-atom ratio, high-temperature superconductivity can be observed in only a few regions. This suggests a search for superconductors with high-transition temperatures and critical fields within these regions.
Annealing behavior of amorphous ferromagnetic Co-Fe-B and Fe-B thin films
Authors: Gangulee A. , Aboaf J. A. , Kobliska R. J.
Published: February 2003

The annealing behavior of amorphous Co-Fe-B and Fe-B thin films, fabricated by rf sputtering in an argon plasma, have been investigated. The magnetostrictive Fe-B films exhibit a perpendicular anisotropy in the as-deposited condition, but after a stress relief anneal an in-plane anisotropy is obtained. An in-plane easy axis develops in the as-deposited Co-Fe-B thin films. The in-plane anisotropy direction in both sets of films can be rotated by annealing in an external magnetic field aligned parallel to the hard axis via a thermally activated process. Preannealing with a magnetic field aligned parallel to the easy axis stabilizes these films to a significant extent. The kinetics of easy axis rotation has a simple logarithmic dependence on time. Analysis of the kinetics of easy axis rotation indicates that preannealing apparently increases the thermal activation energy for this rotation process.
Bounds on the trace of the effective permittivity of anisotropic, heterogeneous mixtures
Authors: Habeger C. C. , Fleischman E. H.
Published: February 2003

Following a mathematical development by Willis [J. R. Willis, J. Mech. Phys. Solids 25, 185 (1977)], limits on the trace of the effective properties of anisotropic mixtures are established. An application in which these limits are useful is discussed.
A new ’’surface-states’’ mode of switching in M-thin insulator-n-p+ devices
Authors: Habib Serag E.-D. , Eltoukhy A. A.
Published: February 2003

The metal-insulator (tunnel) -n-p device (MISS) is known to display current-controlled negative resistance in its I-V characteristics. This negative resistance behavior originates from a positive feedback interaction between the p-n junction and the tunnel metal insulator semiconductor (MIS) parts of the device. The simple structure of the MISS and its amenability to integration has so far been masked by the incomplete understanding of the physics of operation of the device. In this paper, the effect of the surface states at the semiconductor-insulator interface on the MISS behavior is considered. It is shown that the bias dependence of the charge stored in the surface states reduces the switching voltage Vw below the punch-through or avalanche breakdown limits. A simplified model of the MISS is developed taking into account the different roles of the surface states as charge storage centers, recombination centers, and tunnel-current carrying sites. This model is believed to bridge the gap between the previous theoretical models and experimental works.
Radiative recombination measurements in p-type CuInS2
Authors: Vecchi M. P. , Ramos J.
Published: February 2003

The photoluminescence spectra of CuInS2 crystals at 76 K have provided information on the band-to-band and band-to-impurity radiative recombination processes. Thermal treatments in a dynamical vacuum and in atmospheres of S were done on the p-type crystals grown by chemical transport. The changes measured in the photoluminescence spectra before and after the treatments allowed the identification of the dominant acceptor states and their ionization energies. Finally, we report the first observation of radiative recombination transitions to the spin-orbit split valence band of CuInS2.
Nd:YAG laser annealing of arsenic-implanted silicon: Relaxation of metastable concentrations by means of CO2-laser irradiation
Authors: Tsien P. H. , Ryssel H. , Röschenthaler D. , Ruge I.
Published: February 2003

The relaxation of supersaturated arsenic concentrations resulting from Nd:YAG laser annealing of implanted silicon was investigated, using a thermal post-treatment with a stationary 40-W CO2−laser beam. It was found that the relaxation time constant is ∼12 min at 700 °C and ∼20 min at 600 °C.
Instability of ion beams neutralized by co-moving electrons
Authors: Poukey J. W. , Quintenz J. P. , Olson C. L.
Published: February 2003

Analysis and particle simulations are used to show that an ion beam moving in vacuum surrounded by conducting walls can only be stably neutralized by co-moving electrons for currents below the threshold for the Pierce instability. These results indicate that the Pierce instability may be a problem in ion beam fusion schemes that rely on co-moving electrons for neutralization.
Limits of detection for condensation nuclei counters
Authors: Carlon Hugh R.
Published: February 2003

Physical limits restrict the numbers of nuclei that can be detected by cloud chambers and condensation nuclei counters (CNC’s) to about 108–109/cm3. Thus larger numbers will not be detected even when supersaturation s reaches sufficient levels to activate them, e.g., s∼4.85 for Wilson’s ’’cloudlike’’ nuclei from starting temperatures near 0 °C. Recent evidence suggests that water vapor and moist air contain more than 109/cm3 of neutral molecular complexes (water clusters), which were the ’’nuclei’’ observed by Wilson. Thus their true populations cannot be determined by cloud chambers or CNC’s, but they can be inferred by their infrared absorption, suggesting the interesting possibility of an infrared cloud chamber.
Evaluation of scattering loss due to dislocations in LiNdP4O12 laser
Authors: Nakano Jun’ichi , Kubodera Ken’ichi , Miyazawa Shintaro
Published: February 2003

Scattering loss due to dislocations in LiNdP4O12 laser crystals is evaluated by positional change of laser output power. Two 5-mm-thick LiNdP4O12 crystals having different dislocation density profiles are examined. There is no correlation between dislocation density and laser output power up to a dislocation density of 105/cm2.
Influence of thin metal as a top electrode on the characteristics of P-I-N a- Si:H solar cells
Authors: Han Min-Koo , Anderson Wayne A. , Lahri R. , Coleman John
Published: February 2003

Hydrogenated amorphous silicon (a-Si:H) p-n junction solar cells have been fabricated which utilize various metals (Cr, Cu, Al, Pd, Ag) as a top electrode. Experimental and theoretical analysis of photovolatic performance in a-Si:H solar cells as a function of resistivity, optical transmittance, and work function of thin metal films are presented. Metal work function changes the effective built-in potential of p-n junction diodes. Furthermore, a lower work function metal forms a good Ohmic contact for substrate –P+-I-N+– electrode cells, and high work function metals improve Voc of substrate -N-I-P cells. Typical Voc values are 760 mV with Cr–, Cu–, and Al–N-I-P–stainless steel (SS), 700 mV with Pd–N-I-P-SS, 600 mV with Pd–P-I-N-SS, and 540 mV with Cr–P-I-N-SS. Jsc is strongly dependent on transmittance and resistivity of the metal films. Fill factor is independent of the choice of a top electrode. An efficient of 2% has been obtained on a 2 cm2 solar cell.
Production of smoke particles condensed from K+N2O or Zn+O2 vapor
Authors: Hecht J. , Norton M. A.
Published: February 2003

K and Zn metal were evaporated in an inert gas and oxidant atmosphere at pressures of 1–50 Torr. The resultant smoke was analyzed as to size and composition by light scattering and electron microscopy techniques. The formation of K2O and ZnO particles was consistent with previous work on Na2O particle formation.
Field-emission liquid-metal ion source and triode ion gun
Authors: Komuro Masanori , Kawakatsu Hisazo
Published: February 2003

A pointed-filament-type field-emission liquid-metal ion source is designed and employed as a gold ion source. By adding a crossbar across a hairpin bend, the amount of the gold adhering on the filament is increased. The lifetime is estimated to be over 200 h at 10-μA emission current. The emission current increases with increasing extraction voltage up to a saturation value which is ascribed to a limitation of the supply of liquid gold to the needle apex. The value of current density per unit solid angle is 30 μA/sr at a total current of 30 μA, which is of the same order as that obtained from a gallium ion source previously reported. Emission current fluctuations of a few tens of percent of the dc component are observed. In order to regulate the emission current and suppress current fluctuations, a bias electrode in addition to a counterelectrode is placed close to the needle apex. With such a triode structure, the emission current is regulated by a bias voltage of several hundred volts and stabilized to within 1% by means of feedback to the bias voltage of a current monitor output.
Radial oscillations of a relativistic electron beam in an accelerating gap
Authors: Genoni T. C. , Franz M. R. , Epstein B. G. , Miller R. B. , Poukey J. W.
Published: February 2003

Radial oscillations of hollow, relativistic electron beams have been observed on Sandia’s RADLAC I, a multistage high-current linear induction accelerator. These oscillations, which arise because the presence of the accelerating gaps prevents radial force balance, can be responsible for poor beam quality and low current-transport efficiency. The method of magnetic field shaping to suppress oscillations is investigated. Two analytical models are formulated to derive nonuniform fields necessary to maintain force balance in a single-gap geometry. Particle code simulations have been made to test beam propagation in contoured fields. Field shaping does suppress oscillations and is not sensitive to fluctuations in beam and gap parameters.
An analytical solution of kinks and nonlinearities driven by near-field displacement instabilities in stripe geometry diode lasers
Authors: Su C. B.
Published: February 2003

An analytical expression which describes the lateral shift of the lasing mode in a diode laser as an implicit function of injection current is derived for stripe geometry lasers, without numerically evaluating the full self-consistent carrier and field equations. If the onset of the lateral mode shift is associated with a kink in the optical power-current characteristic, then the predicted kink power as a function of stripe width agrees quite well with experiment. Self-focusing of the near field is predicted to occur for wider stripe lasers, in general agreement with observation. The effect of the strain-induced dielectric profile on the kink power is calculated and found to be minimal for oxide isolated lasers of practical active layer depth. The parameters which profoundly affect the kink power are stripe width, carrier diffusion length, and near-field width.
Surface acoustic wave studies of hydrogen entry into a Ni-base alloy
Authors: Lunarska Ellina , Fiore Nicholas F.
Published: February 2003

Rayleigh acoustic waves were propagated along the surface of a sheet sample of a Ni alloy while the alloy was undergoing electrolytic charging with hydrogen. The waves were propagated, at frequencies from 2 to 15 MHz, from a transmitting to a receiving transducer, and their attenuation and velocity were monitored. A number of experiments was conducted to ensure that Rayleigh conditions were met and that extraneous results due to such effects as passive film changes and bubble formation were minimal. During cathodic polarization, wave velocity and attenuation decreased. The attenuation decrease followed two stages: an instantaneous one, probably due to polarization effects in the electrolyte, and a gradual one associated with the entry of hydrogen into the alloy. Both the instantaneous and gradual decreases were reversible and were recovered when polarization was removed. The kinetics of the recovery of the gradual component of attenuation were described by the Granato-Hikata-Lücke model for unpinning of dislocations by point defects. All results indicated that the surface wave technique was sensitive to hydrogen atom entry into the surface and that the entering atoms migrated to and pinned dislocations within a layer of thickness much less than the Rayleigh wavelength.
Rotational temperature measurement of NO gas using two-photon excitation spectrum
Authors: Ozaki Tadao , Matsui Yoshihiko , Ohsawa Toshihiko
Published: February 2003

The rotational temperature of nitric oxide gas has been measured by means of a single-beam two-photon excitation spectrum method using a pulsed continuously tunable dye laser. The nitric oxide gas was enclosed at about 40 Torr in a quartz cell which was put in an electric oven. The NO γ (0-0) band and R11+Q21 branches were used to obtain the two-photon excitation spectrum. The rotational temperatures were determined using the fact that molecules are distributed in the rotational levels according to the Boltzmann law. The temperature range was from room temperature to about 470 K. Observed temperatures were in good agreement with cell temperatures which were obtained by using a thermocouple.
Measuring fuel ρR for inertial fusion experiments using neutron elastic-scattering reactions
Authors: Skupsky Stanley , Kacenjar Steve
Published: February 2003

Neutron elastic-scattering reactions are examined by computer simulation and found to be potentially useful as a diagnostic for fuel ρR (density-radius product). We show how previously anticipated uncertainties can be removed by correlating the distortion of the scattered-ion distribution with energy loss of DD protons for low ρR and with D-He3 protons for large ρR. This diagnostic could be used to directly measure ρR of the fuel without special target preparation for target ρR≲0.2 g/cm2.
Investigation of tunneling processes in laser-induced ionization of argon
Authors: Baldwin K. G. H. , Boreham B. W.
Published: February 2003

A method of determining the laser intensity necessary for ionization of atomic states is described. Results are presented for ionization of argon states I–V at 10−4 Torr using a short (25 psec)-pulse neodymium laser at intensities up to 4×1016 W cm−2. The results agree with computer calculations of the Keldysh tunneling model in the regime γ⩽1 and with results previously obtained in helium. The electron energy spectra technique employed further verifies the existence of the ponderomotive force.
Excitation mechanisms responsible for the 615.0-nm oscillation in a He-Hg ion laser
Authors: Horiguchi Shiro
Published: February 2003

Selective excitation processes responsible for the lasing of singly ionized mercury at 615.0 nm in a He-Hg pulsed discharge have been studied by observing the time variation of the populations of the reactants using the Hook method and the side-light method. It is found that in the decaying plasma of a pulsed discharge, the principal process is the Penning reaction, while during the discharge the charge-transfer-type reaction predominates.
Fluctuations and turbulence in an electric field bumpy torus plasma
Authors: Roth J. Reece , Krawczonek Walter M. , Powers Edward J. , Kim Young C. , Hong Jae Y.
Published: February 2003

In this experiment, strong radial electric fields were imposed along the minor radius of a steady-state bumpy torus plasma by biasing it with electrodes maintained at kilovolt potentials. Digitally implemented spectral analysis techniques were used to experimentally investigate the characteristics of the fluctuations of plasma number density and electrostatic potential below the ion plasma and ion cyclotron frequencies. The dispersion relation between ω and k for azimuthally propagating waves was determined experimentally, and, when linear, was consistent with the E/B drift velocity. Above 100 kHz, the power spectra of both density and potential fluctuations obeyed a power law of the form P(ω) α ω−p. The spectral index p of this plasma turbulence assumed values which varied with operating conditions. The fluctuations of density and potential ranged from highly coherent rotating spokes, to highly turbulent conditions with a Gaussian distribution in amplitude.
Intense microwave generation from a non-neutral rotating E layer
Authors: Destler W. W. , Romero H. , Striffler C. D. , Weiler R. L. , Namkung W.
Published: February 2003

The radiation produced by a hollow, non-neutral, rotating, relativistic E layer propagating inside a coaxial cylindrical drift tube has been investigated theoretically and experimentally. The measured radiation spectrum is very broadband in agreement with theory, though a shift in the spectrum can be achieved by a preloaded azimuthal density structure.
Photoluminescence of doped La10S14O
Authors: Bludau W. , Wichelhaus W.
Published: February 2003

The rare-earth oxysulfide La10S14O, doped with cerium, emits a bright luminescence band peaking around 6350 Å at room temperature. This red emission is quenched by copper impurities inadvertently present in insufficiently purified La10S14O. The Cu impurity in turn brings forth an emission band peaking around 7200 Å. The red 6350-Å luminescence has technological importance for color TV screen and luminescent lamp application. We report on the photoluminescence properties of doped La10S14O and on refinements of its structure determination.
Photoluminescence of Ge-doped AlxGa1−xAs
Authors: Waters R. G.
Published: February 2003

The photoluminescence of Ge-doped AlxGa1−xAs (with 0.26 < x < 0.43) has been investigated. For carrier concentrations ∼1017 cm−3 a new luminescence line is observed. An analysis based on the configurational coordinate model indicates that a complex center is involved. The center is believed to be a GeAs−VAs complex from which emission has also been observed in GaAs.
Theoretical and experimental investigation of the dynamics of pulsed laser annealing of amorphous silicon
Authors: Bhattacharyya Anjan , Streetman B. G. , Hess K.
Published: February 2003

The dynamics of surface melting and resolidification of self-ion-implanted amorphous silicon (∼4000 Å layer) during irradiation with a Q-switched Nd:glass laser (λ = 1.06 μm) has been studied both theoretically and experimentally. The technique of finite-difference equations is used to solve the nonlinear one-dimensional heat conduction equations for the solid and liquid phases, taking into account appropriate time-dependent boundary conditions for finding the position of the melt front as a function of time. In addition we present experimental results for the time-dependent optical reflectivity of self-ion-implanted amorphous silicon to study the transition from amorphous to crystalline phases during annealing with a Nd:glass laser pulse.
Experimental and calculated depth distributions of damage and projected ranges of 20-keV 4He ions in nickel
Authors: Fenske G. , Das S. K. , Kaminsky M. , Miley G. , Terreault B. , Abel G. , Labrie J. P.
Published: February 2003

A recently improved sample-sectioning technique allowed us to obtain the entire depth distribution of damage (e.g., cavities) produced by 20-keV 4He+ ions injected into annealed, polycrystalline nickel held at 500 °C. We have also obtained the depth profile of the implanted helium concentration using the elastic recoil detection technique. These experimental depth profiles have been used to test several theoretical predictions for projected range and energy deposition profiles (e.g., based on transport theory or Monte Carlo calculations).
Resistivity reduction in heavily doped polycrystalline silicon using cw-laser and pulsed-laser annealing
Authors: Shibata T. , Lee K. F. , Gibbons J. F. , Magee T. J. , Peng J. , Hong J. D.
Published: February 2003

The resistivity reduction in heavily doped polycrystalline Si by laser annealing and its increase during subsequent heat processing have been studied. Both cw and pulsed lasers have been used for the experiments and the results are compared. In both cases laser annealing reduces the Si resistivity by a factor of 2–3 compared to the furnace annealing. A limited resistivity increase is observed in all laser-annealed Si samples during subsequent thermal annealing, with the final values for resistivity being lowest for cw-laser-annealed Si. The subsequent annealing behavior observed for cw- and pulsed-laser-annealed Si is interpreted in terms of the different grain structures found in these films. It is demonstrated by transmission electron microscope studies that the resistivity instability is caused by the precipitation of dopants in the form of rod shaped structures localized at the grain boundaries as well as within the crystallites.
Mode theory of uniform waveguides filled with dielectric inhomogeneous along one direction only
Authors: Lin Weigan
Published: February 2003

Straight waveguides filled with inhomogeneous dielectric whose permittivity varies along one dimension are studied. Emphasis is given to the modes of propagation and to the calculation of the propagation constants. Exact solutions are given for some special cases. In some of these only asymptotic or polynomial solutions have been available previously. No restriction is placed on the waveguide dimensions so that results developed here apply to the transmission of optical frequency waves as well as to microwave and millimeter waves. For the waveguide problems examined here, results obtained cannot be directly drawn from the existing literature, and so have been worked out from the fundamental theory of differential equations.
Behavior of diffused junction silicon solar cells in the temperature range 77–500 K
Authors: Arora J. D. , Mathur P. C.
Published: February 2003

The absorption coefficient α for Si, using an indirect transition theory, has been calculated in the temperature range 77–520 K as a function of wavelength. The computed values of α have been used to calculate the performance parameters, such as Jsc,Voc, FF, and η as a function of temperature for diffused junction n+p Si solar cells. The calculated results have been experimentally verified by measuring the current-voltage characteristics at 1 sun of two n+p solar cells having base resistivity 1 and 10 Ω cm, respectively.
Study of a pulsed generator based on an iron-free asynchronous machine
Authors: Sultanem F. , Bleijs C. A. , Rioux C. , Rioux-Damidau F.
Published: February 2003

Two previous articles have described iron-free asynchronous machines capable of generating extremely high powers per unit weight. This article considers their use as pulse generators, for which they represent a simple and very attractive solution for generating very high-energy impulses.
Determination of the field effect in low-conductivity materials with the charge-flow transistor
Authors: Senturia S. D. , Rubinstein J. , Azoury S. J. , Adler D.
Published: February 2003

A new method for determining the screening length, static permittivity, and work function from field-effect measurements in low-conductivity materials such as amorphous semiconductors is described. The method is based on the charge-flow transistor (CFT), a device structure which resembles a conventional metal-oxide-semiconductor field-effect transistor (MOSFET), but with a portion of the gate metal replaced by the material under study. The interpretation of conventional field-effect measurements is complicated by the simultaneous need to know both the mobility and the distribution of charges in the material. The CFT method complements conventional field-effect measurements by providing independent information on the distribution of charges. This paper outlines the theory behind the new method, and presents the first experimental results that illustrate in part its use. The material used in these first experiments is a multicomponent chalcognide glass, Te39As36Ge7Si17P1.
An energy density function for papillary muscle encompassing both elastic and contractile properties
Authors: Klip Willem , Hefner Lloyd L. , Donald Thomas C. , Reeves David N. S. , Hazelrig Jane B. , Klip Dorothea A.
Published: February 2003

Not only for the the heart, but also for papillary muscle a contraction variable κ can be defined (in analogy with the deformation variable λ) in a phenomenological approach that makes use of the finding that two of the three constants (c2 and c3) in the isochronics of such a muscle can be considered functions of the third one (κ). This fact provides four constants (k1, k2, k3, and k4) of an energy density function. A tentative bridge to the heart (for clinical application) is laid; four analogous constants of the same order of magnitude can be measured there.
Further investigations and comments on the dynamic scattering mode in nematic liquid crystals
Authors: Hérino Roland
Published: February 2003

Transverse observations of the dc dynamic scattering of a nematic liquid crystal are presented. In the presence of controlled unipolar injection, the turbulences always appear at the discharge electrode, and do not propagate to the injecting electrode when the cell is separated into two independent regions by a diaphragm. The instability is found to be related to the electrolysis of the injected charge carriers rather than to the growth of a space charge in the direction of the field.
Electronic effect on the elastic constant c44 of n-type silicon
Authors: Kim C. K.
Published: February 2003

The change of the elastic constant c44 of Si is theoretically investigated in the presence of both free electrons and bound electrons. While in p-type semiconductors the bound-hole contribution to the change of the elastic constant c44 is qualitatively different from the free-hole contribution, the bound-electron contribution in n-type Si is essentially identical to the free-electron contribution. It is shown that this phenomenon results from the facts that the donor ground state of silicon is a singlet and that the six conduction valleys of silicon are uniformly lowered by a shear acoustic wave.
Declustering and melting threshold study in laser irradiated Si(As)
Authors: Rimini E. , Chu W. K. , Mader S. R.
Published: February 2003

The sheet resistivity of 40-keV, 1016 As/cm2-implanted Si decreases by a factor of 3 after irradiation with a suitable energy density of Nd:YAG laser at 1.06 or 0.53 μm. The changes in conductivity occur with the melting and quenching of the surface layer as indicated by profile broadening, and they are associated with the declustering process during solidification. The threshold energy density for melting is studied. At 0.53 μm, the threshold is the same (∼0.4 J/cm2) for both as-implanted and thermally preannealed Si. At 1.06 μm, the threshold for the as-implanted sample is ∼5 J/cm2, while the threshold for the preannealed sample is ∼10 J/cm2. These results are in agreement with the absorption changes due to crystalline structure alterations and dopant.
A mechanism for endurance failure in metal-nitride-oxide-semiconductor device structures
Authors: Pryor R. W.
Published: February 2003

A new mechanism is postulated for endurance failure in metal-nitride-oxide-semiconductor and similar , amorphous, multilayer, dielectric charge-storage devices. The mechanism is based on the modification of local energy levels on an atomic scale due to structural adjustments occurring during times of applied high-field stress (write/erase cycling). The modified energy levels that are frozen in after removal of the high-field stress, due to structural irreversibilities, allow enhanced communication between what would otherwise be completely localized states. These new communicating states are called delocalized states. The presence of such delocalized states enhances the continuation of the delocalization process, eventually leading to the formation of a network of states throughout the solid. This process results in enhanced decay and, eventually, breakdown of the film. Preliminary calculations and the presently available experimental data substantially agree with the postulated mechanism.
Analysis of stress effects on the domain and field configuration of SiFe sheets with coating
Authors: Pfützner H.
Published: February 2003

For domain analyses a new colloid technique was used that allows observations on coated sheets without application of an external magnetic field. Application of tensile stress decreased domain wall spacing and eliminated spike, tree, and other supplementary structure. Low compression caused extensive domain widening linked with the formation of tree patterns. With rising compression an increasing proportion of transverse domains of decreasing width was formed. Stress-caused modifications of the tangential field configuration of magnetized coated samples were studied by means of computer-controlled raster scanning with Hall plates. Compression generated both an increased field homogeneity accompanied also be increased local magnetic resistivity at almost all points of the sample. Tensile stress caused modifications differing from point to point.
The frequency dependence of one- and three-dimensional photoacoustic effects with solids
Authors: Chow H. C.
Published: February 2003

The chopping frequency dependence of one- and three-dimensional photoacoustic signals is presented. In both cases there exist frequency regimes in which this dependence exhibits a richer variety than has been recognized hitherto.
Small-signal ac response of dielectric materials containing static space-charge fields: Application to ionic conductors and MIS structures
Authors: Moriarty John A.
Published: February 2003

An efficient and quantitatively accurate scheme for obtaining the small-signal ac response of dielectric materials containing static space-charge fields near their boundaries is developed in the context of a general linear-response formalism. The technique improves and greatly extends the earlier method of Hoyen et al. used to treat space-charge-limited transport in the ionic conductor AgCl. The general formalism is here implemented in detail for the case of one fully mobile, nonrecombining carrier in a uniformly doped material subject to arbitrary electrode boundary conditions. Illustrative applications to metal-insulator-semiconductor (MIS) structures and ionic conductors are considered. Extension of the method to more complex situations, involving minority-carrier transport, nonuniform doping, and/or generation and recombination phenomena, appears readily feasible.
Improved properties of InxGa1−x As layers grown by molecular-beam epitaxy on InP substrates
Authors: Kawamura Y. , Asahi H. , Ikeda M. , Okamoto H.
Published: February 2003

Improvement in crystallographical, electrical, and optical properties of InxGa1−x As molecular-beam epitaxial films grown on InP substrates has been made by using a modified premixing method and a flash heat treatment of substrates just prior to growth. All of the relevent properties, especially the photoluminescence property, of the grown films are comparable to the corresponding liquid-phase epitaxial films. The interfacial recombination velocity at the heterojunction between the molecular-beam epitaxial epilayer and the substrates is also comparable with those for the other sets of heterojunctions, such as AlxGa1−x As/GaAs and InxGa1−x P/GaAs.
The work function of sputter-formed Re-1% Pt
Authors: Gordon R. L. , Stoffels J. J. , Porter Spencer K.
Published: February 2003

High-rate sputter deposition has been used to make free-standing ribbons of Re-1% Pt alloy. Changes in the work function and surface composition of the alloy as a function of temperature are reported. Segregation of Pt to the surface was accompanied by a decrease in work function indicating electron transfer from Pt to Re. When the Pt-to-Re ratio at the surface reached 0.26, the work function of the alloy was 1.44 eV below that of a pure Re reference ribbon. Analysis of the work function change as a function of surface concentration of Pt on the Topping model yielded values of 7.1×10−30 C m and 19.4 Å3 for the dipole moment and polarizability, respectively, of surface Pt atoms. Electron transfer from Pt to Re is opposite to that expected on the basis of published values of electronegativity and is interpreted as indicating significant exchange of 5d electrons in the alloy.
Factors influencing the formation and growth of faulted loops in BF+2 -implanted silicon
Authors: Chen L. J. , Wu Y. J. , Wu I. W.
Published: February 2003

Transmission electron microscopy has been applied to study faulted loops in BF+2 -implanted silicon. (001)- and (111)-oriented silicon were irradiated by BF+2 ions to doses of 1×1014–1×1015 cm−2 followed by annealing at 1000-1200 °C in dry N2, dry O2, and wet O2 for different periods of time (1 min. to 2 h). The oxygen content in the annealing ambient was found to be of critical importance in the nucleation and growth of faulted loops. The presence of oxygen atoms lowered the activation energy for the nucleation of faulted loops and increased the heterogeneous nucleation sites as well as accelerated the growth of loops. For the same foil, the difference in the growth rate of loops was explained in terms of the competition of the inflow of interstitial flux from the oxide/silicon interface and vacancy flux from the rest of silicon towards the interface. There was indication that the difference may arise because the defects were of different natures. Stress effect was invoked to discuss why faulted loops were more prominent in (001)-oriented, lower-dose samples than in (111)-oriented, higher-dose samples, respectively.
Magnetic coupling and photoferromagnetism in CdCr2Se4
Authors: Sanford Norman , Nettel Stephen J.
Published: February 2003

We inquire as to a relation between the occurrence of photoferromagnetism in CdCr2Se4 and the mechanism of its ground-state ferromagnetic coupling. To explain the ground-state coupling we extend some of the localized orbital considerations of Goodenough to an itinerant-electron coupling model. The coupling involves hybridized Se-Cr2+ Bloch functions, with virtual excitations into the upper Cr-3d band. We find that there is reason to expect this coupling to be dominant over superexchange. We also find that the disturbance of this coupling by light is a major cause of the photoferromagnetism. The RKKY coupling is derived with the second-order pseudo-Hamiltonian of Pryce.
Stochastic treatment of electron multiplication without scattering in dielectrics
Authors: Lin D. L. , Beers B. L.
Published: February 2003

By treating the emission of optical phonons as a Markov process, a simple analytic method is developed for calculating the electronic ionization rate per unit length for dielectrics. The effects of scattering from acoustic and optical phonons are neglected. The treatment obtains universal functions in recursive form, the theory depending on only two dimensionless energy ratios. A comparison of the present work with other numerical approaches indicates that the effect of scattering becomes important only when the electric potential energy drop in a mean free path for optical-phonon emission is less than about 25% of the ionization potential. A comparison with Monte Carlo results is also given for Teflon.
Acoustic velocity and refractive index of fluid hydrogen and deuterium at high pressures
Authors: Brody E. M. , Shimizu H. , Mao H. K. , Bell P. M. , Bassett Wm. A.
Published: February 2003

Using Brillouin scattering we have measured the pressure dependence of the accoustic velocity and refractive index of fluid hydrogen and deuterium at room temperature in a diamond anvil cell up to solidification at 55 kbars. We find good agreement between our velocities and those calculated from an equation of state given by Liebenberg et al. The refractive indices are fit by a Lorenz-Lorentz relation yielding a polarizability of 8.17±0.l×10−25 cm.3
Radial distribution of a Cd neutral ground-state density in a positive column of a He-Cd discharge
Authors: Watanabe Kazufumi , Watanabe Shinzi , Sakurai Takeki
Published: February 2003

A radial distribution of the cadmium neutral atoms in the ground state has been measured by an absorption method in the positive column of a He-Cd discharge. A great decrease is found at the tube axis. The density at the axis and the distribution strongly depend on discharge current and helium pressure, even if the cadmium oven temperature is fixed. The radial distribution is theoretically calculated from a rate equation and it is found that the distribution is determined by the ratio of the ionization rate to the diffusion constant. From the comparison between theoretical and experimental results, the diffusion constant of cadmium neutral atoms at 1 Torr and 300 K is estimated to be 15±5 cm2/sec in an actual discharge.
Electric discharge excited TlI-Xe mixtures
Authors: Wildman D. W. , Schumann L. W. , Gallagher A. C.
Published: February 2003

Pulsed, high-power, nonequilibrium discharges have been operated in TlI-Xe mixtures at typical TlI densities of 1015–1017 cm−3, Xe densities of ∼1019 cm−3, and power densities of 105–106 W cm−3. The steady-state emission spectrum was measured for the wavelength region 275-850 nm, and it was used to obtain the populations of the Tl and Xe excited states. The fraction of TlI dissociated in the discharge is also reported as a function of TlI, Xe, and current density. A phenomenological model for the results is discussed.
Generation of a highly magnetized plasma by using the superconducting coil
Authors: Idehara Toshitaka , Tomita Naoyoshi , Kanemaki Tomohiro , Yagi Hisao
Published: February 2003

The magnetic field, the intensity of which can be increased up to 4 T, is produced continuously by using the superconducting coil and is applied to the dc discharge plasma. This ultrahighly magnetized plasma (ULMAP) may be used in the experimental studies of plasma physics under the extreme condition. The new region of plasma parameters where the averaged ion Larmor radius is smaller than the Debye length is attained. The advantage of this device is that the Ohmic loss in the coil is negligibly small, and that a highly magnetized plasma is generated without an appreciable waste of electric power.
A radiation and convection model of the vertical mercury arc containing sodium and scandium iodides
Authors: Zollweg R. J. , Liebermann R. W. , McLain D. K.
Published: February 2003

A model has been developed for a multicomponent gas discharge containing several radiative species, Hg, I, Na, Sc, Sc+, and ScI, subject to radial and axial segregation. Net emission coefficients for self-absorbed radiation from these species are deduced individually and collectively from experiment and imprisonment theory. The vertical arc convection model has been modified to take into account the axial variation of material parameters with segregation and to calculate quartz wall temperatures. Calculated lamp parameters are found to be in reasonable agreement with experimental data.
Transmission electron microscope study of ion beam annealing effects of ion-implanted and evaporated amorphous silicon
Authors: Chen L. J. , Wu Y. J. , Yang Y. C. , Hsieh K. P. , Lin M. S. , Huang R. S.
Published: February 2003

High power ion beam annealing has been applied to ion-implanted and evaporated amorphous silicon samples. Microstructures induced by this novel technique have been investigated by transmission electron microscope. The analysis of diffraction patterns and direct images of ion beam annealed as well as thermally annealed specimens indicates that ion beam annealing is a promising technique to process ion-implanted and evaporated amorphous samples. It was found that several seconds of intense ion beam bombardment produced similar effects as did 1-h 600–900 °C thermal annealing.
Sheet resistivity and transmission electron microscope investigations of BF+2 -implanted silicon
Authors: Chen L. J. , Wu I. W.
Published: February 2003

Sheet resistivities of post-implantation annealed BF+2 -implanted silicon were measured by four-point probe method as a function of implantation dose, annealing temperature, and time. The resistivities of the implanted layer were found to be lower for samples annealed at higher temperature as well as irradiated to higher dose. Detailed transmission electron microscope investigations were made for samples irradiated to 1×1014 cm−2. Disordered zones were found to transform to microscopic clusters and small Frank loops on {111} planes upon 600 °C annealing. The rodlike defects in samples annealed at 700–800 °C are identified to be elongated perfect dislocation loops lying on or near {111}, interstitial in nature, with Burgers vectors b = 1/2 〈110〉 perpendicular to their elongated directions. They disappeared upon 900 °C annealing. The dislocation loops that coexisted with the rodlike defects consisted of interstitial perfect prismatic loops and extrinsic Frank loops, mainly hexagonal or circular in shape. They persisted after 900–1000 °C annealing. Half circular faulted loops and larger faults were found in 1000–1200 °C annealed samples. The loops were identified to be extrinsic Frank loops, lying on {111}. The formation and growth of these loops is likely related to the effect of oxidation in annealing.
Crystallization of amorphous Fe81B13.5Si3.5C2
Authors: Swartz J. C. , Kossowsky R. , Haugh J. J. , Krause R. F.
Published: February 2003

Crystallization of 25-mm wide ribbon of metallic glass Fe81 B13.5Si3.5 C2 (Metglas 2605SC) has been studied by differential scanning calorimetry, measurement of magnetic coercivity, x-ray diffraction, and transmission electron microscopy. Samples were annealed isothermally for 5–180 min between 345 and 450 °C. Dendritic precipitates of alpha iron are detected after anneals ?375 °C and cause the first exothermic peak. A second exothermic peak corresponds to crystallization of the balance of the matrix primarily into body-centered-tetragonal (bct) grains. The results are collated in a time-temperature-coercivity diagram. The minimum coercivity after field annealing is 0.03 Oe.
Deep levels in electron irradiated edge-defined film-fed growth ribbon silicon
Authors: Jaworowski A. E. , Pierce C. B. , Burdick S. , Corbett J. W. , Hanoka J. I.
Published: February 2003

Schottky diodes were fabrication on (EFG) edge-defined film-fed growth 1 Ω cm p-type silicon ribbon samples, which were then irradiated with 2-MeV electrons at near room temperature (∼310 K), and were studied using conventional capacitance transient (DLTS) techniques. Several majority carrier traps were consistently observed. The thermal stability of these centers was determined by isochronal annealing studies. Tentative identifications, based primarily on comparison with energy levels and thermal stability of defects prevoiusly observed in aluminum or boron doped and electron-irradiated silicon, are as follows: Ev+0.165 eV, Al-related; Ev+0.295 eV, vacancy+oxygen+boron; Ev+0.39 eV, carbon-interstitial + carbon-substitutional; Ev+0.71 eV, Fe-related.
Dose thresholds for implantation of iron-doped indium phosphide
Authors: Zeisse Carl R. , Reedy Ronald E.
Published: February 2003

Silicon and beryllium ions have been implanted at 300 °K into iron doped semi-insulating InP substrates. In all cases a threshold dose was found in the high 1011 cm−2 to mid 1012 cm−2 range which depends both on the substrate and the ion being implanted. A simple model identifies the threshold fluence for n-type implantation with the excess iron in the substrate and the threshold for p-type implants with the background impurities in the substrate.
Elasticity of Mo-Re and W-Re alloys under hydrostatic pressure
Authors: Katahara K. W. , Manghnani M. H. , Devnani N.
Published: February 2003

The elastic moduli of single crystals of Mo-16%Re, Mo-29% Re, and W-11% Re have been measured to 0.5 GPa (5 kbar) hydrostatic pressure at room temperature. The composition dependence of the pressure derivatives of the moduli follows the trends established for Nb-Mo and Ta-W alloys. This finding was unexpected since the shear modulus, C′ = (C11−C12)/2 has a sharp peak in its composition dependence at e/a = 6.0. The results are explained in terms of the differing effects of compression on different d-electron subbands. Because dC′/dP decreases with increasing Re content, it is also suggested that the compositional range for stability of the bcc structure decreases with increasing pressure.
Shock compression of aluminum, copper, and tantalum
Authors: Mitchell A. C. , Nellis W. J.
Published: February 2003

Hugoniot curves for Al (alloy 11000), Cu (type oxygen-free high-conductivity), and Ta have been measured in the shock pressure range 30–430 GPa (0.3–4.3 Mbar) with a two-stage light-gas gun. Impactor velocities were measured to 0.1% by flash radiography. Shock velocities were measured to 0.5–1.2% with an electronic detection system with subnanosecond time resolution. Our data and those of other workers were fitted to a linear relation between shock and mass velocities. The fractional standard deviations of the data from the fits range from 0.6 to 0.9% for the three metals. Methods of data analysis and error analysis for individual data points and for the least-squares fitting to the data sets are presented. Bands of uncertainty about the fits, arising from experimental uncertainties in the data, are presented and are used to calculate the systematic error introduced by the method of shock-impedance matching. The accuracy of the data and of the fits qualifies these metals as equation-of-state standards for shock-wave experiments.
A model of crystal potential from axial-channeling radiation
Authors: Swent R. L. , Pantell R. H.
Published: February 2003

One application of radiation from channeled electrons is that the potential in a crystal can be calculated from the measured radiation energies. The procedure is to assume a potential function with undetermined coefficients that can be adjusted so that the energies calculated from this function match the data points. In this manner the potential is determined for the 〈111〉 axis in silicon and compared to that obtained from the Moliere approximation to the Thomas-Fermi model.
Photocapacitance studies of CdS:Cu
Authors: Grimmeiss H. G. , Kullendorff N. , Broser R.
Published: February 2003

Schottky diodes of copper doped CdS have been studied using photocapacitance techniques. Copper doping of CdS gives rise to deep hole states in the lower half of the band gap. The binding energies of the ground state and excited state are 1.1 and 0.34 eV, respectively. Optical emission of both holes and electrons as well as internal transitions followed by thermal emission of holes have been studied and absolute values of photoionization cross sections have been measured. The results are related to previous measurements of luminescence, absorption, photoconductivity, and photo-Hall effect. A model for the electronic structure of the dominant copper related center is discussed.
Stabilized injection locking light amplification of a 1.15-μm He-Ne laser
Authors: Urisu Tsuneo , Sugeta Takayuki , Mizushima Yoshihiko , Tsunenari Kinji
Published: February 2003

Stable injection locking light amplification with over 13-dB gain value was successfully demonstrated in the He-Ne 1.15-μm laser system stabilized by hill-climbing servo frequency control. Basic formulas for injection locking light amplifier operation were derived, taking the inhomogeneous gain effect into consideration. The input power dependence of the injection locking frequency range was measured in detail for several mirror reflectivities. Deviation from the well-known square-root dependence of the locking range versus input power relations was observed and ascribed to the inhomogeneous gain effect. Relations between input and output light polarizations were investigated.
Noise from equilibrium enthalpy fluctuations in resistors
Authors: Weissman Michael B. , Dollinger Gavin D.
Published: February 2003

The theory of equilibrium enthalpy fluctuations in resistors is presented. Measurements of excess noise in an electrolyte resistor are compared with the Green’s function for change in resistance caused by changes in power dissipation. The two measurements are found to obey a relationship predicted by thermodynamics.