bluuebunny/crossref_metadata_2025 huggingface dataset:
Copper-cadmium halide photochromic glasses: Evidence for a colloidal darkening mechanism
Authors: Trotter D. M. , Schreurs J. W. H. , Tick P. A.
Published: February 2003

Optical absorption and electron paramagnetic resonance (EPR) spectra of darkened photochromic glasses containing both copper halides and cadmium halides are presented. Optical absorption spectra, calculated on a colloidal copper model with mean-free path (MFP) and quantum-size effect (QSE) corrections to the bulk metal dielectric constant, are fit to the data. Particles of the size derived from the MFP correction are found to be too large to be produced by photolysis of the phase-separated droplets, presumed to be CdCl2:CuCl decorated with CuCl specks, observed in these glasses. The QSE indicates the presence of oblate spheroidal copper particles with aspect ratios between 1.8 and 3.5 and major diameters ≊8 nm, depending on the heat treatment which the glass has received. The uv-induced EPR spectra show a peak due to Cu2+ ions with halide ions as ligands superimposed on another, broad-winged peak which is attributed to pure or nearly pure CuCl2. These data are consistent with a darkening mechanism in which colloidal copper particles are formed by disproportionation of Cu+ in the CuCl specks and the CdCl2:CuCl droplets.
Some characteristics of pulsed nozzle beams
Authors: Izawa M. , Kita S. , Inouye H.
Published: February 2003

Some characteristic properties of pulsed nozzle beams produced with an automobile fuel injector were observed. A commercial fuel injector was modified to produce a beam pulse of a regular square shape. The beam pulse of 5 ms is again chopped by a slotted disk chopper to make a shorter burst at an arbitrary portion of the original pulse. Rotation of the disk chopper and actuation of the injector are synchronized by a microcomputer. Time-of-flight measurements were performed using beams of 15.6-μs width formed in this way. Beam fluxes were measured with a flow-through detector. The maximum beam fluxes and terminal speed ratios obtained for several gases in this work are comparable to the values published by other workers. Recoils of beam molecules from the skimmer and its vicinity significantly affect the quality of the pulsed beams.
Transverse electron guns for plasma excitation
Authors: Yu Zengqi , Rocca Jorge , Meyer Jack , Collins George
Published: February 2003

We report a plasma gun, which generates on a continuous basis, kilowatt electron beam discharges (e.g., 0.4 A at 4 kV) in an ambient pressure 0.1–1 Torr without differential pumping. Gun design characteristics, operating parameters, and measured beam profiles are given. Electron beam generation on a pulsed basis has also been studied. More than 100 A of beam current has been measured with a Faraday cup biased to −100V. A trapped electron beam scheme for achieving efficient deposition of the electron beam energy in a gas medium is described.
uv laser triggering of high-voltage gas switches
Authors: Woodworth J. R. , Frost C. A. , Green T. A.
Published: February 2003

Two different techniques are discussed for uv laser triggering of high-voltage gas switches using a KrF laser (248 nm) to create an ionized channel through the dielectric gas in a spark gap. One technique uses an uv laser to induce breakdown in SF6. For this technique, we present data that demonstrate a 1-σ jitter of ±150 ps for a 0.5-MV switch at 80% of its self-breakdown voltage using a low-divergence KrF laser. The other scheme uses additives to the normal dielectric gas, such as tripropylamine, which are selected to undergo resonant two-step ionization in the uv laser field.
Kinetics of silicon stacking fault growth/shrinkage in an oxidizing ambient containing a chlorine compound
Authors: Tan T. Y. , Gösele U.
Published: February 2003

A kinetic model for the growth and shrinkage of oxidation-induced stacking faults (OSF) in silicon in an oxidizing ambient containing a chlorine compound is developed. The main assumption used in the model is that the vacancy injection rate due to Si-Cl compound formation is essentially independent of the silicon self-interstitial injection rate due to SiO2 growth. That is, the process of Si-Cl compound formation is not correlated with the process of SiO2 growth. This permits us to calculate the OSF size from RClSF = 1640t0.75  exp(−2.5/kT) −(4.86×109t/ kT) exp(−5.02/kT)−RCl , where RClSF is one half the OSF length (in chlorine oxidation) in cm, t in sec, kT in eV, and RCl = btm with b and m determined from experimental data. RCl represents the further shrinkage of OSF size due to the action of chlorine in addition to that due to stacking fault energy. The agreement between this model and available experimental results is satisfactory. We have found that m adopted values between 0.5 and 1, indicating that Si-Cl formation changes from diffusion limited processes to interface reaction limited processes, and this is sensitive to chlorine content in the ambient and to oxidation temperatures. A limited number of data are useful for arriving at the activation energy for vacancy injection due to Si-Cl compound formation of 2–2.5 eV, and for concluding that the most likely Si-Cl compound formed is SiCl.
Failure prediction for long length optical fiber based on proof testing
Authors: Mitsunaga Yutaka , Katsuyama Yutaka , Kobayashi Hirokazu , Ishida Yukinori
Published: February 2003

A new method for reliability assurance of long length optical glass fibers is presented. This method is based on a simple equation by fracture-mechanics theory and provides failure probability prediction for fibers after proof testing. The prediction is made by using dynamic fatigue data obtained by simple tensile tests and failure number during proof testing. The experimental results are found to be in good agreement with those predicted by the theory, and it is verified that the method is useful to make reliability assurance of long optical fibers for long- term use.
Phase transitions in compound semiconductor films triggered by laser irradiation
Authors: Andrew R. , Baufay L. , Pigeolet A. , Laude L. D.
Published: February 2003

The preparation of AlSb thin films by pulsed laser annealing of Al-Sb sandwiches is studied in order to resolve some past uncertainty about the temperature rise induced by the laser pulse. Using 1000-Å-thick 2-layer films supported by transmission electron microscope grids, we investigate the energy threshold for transformation as a function of pulse duration (from 15 ns to 100 ms) and of ambient temperature up to ∼600 K. We thence calculate the temperature effect directly induced by the laser to be ∼930 K, whereas inert gas furnace anneals of identical films show transformation at this temperature occurring only in times ≳100 sec. We discuss the isoenergetic nature of the system for short-laser pulses and the role of the heat of formation, and propose a model which is then shown to work equally well for the systems CdTe, CdSe, and AlAs. We conclude that the reaction is thermally triggered by the laser pulse, but is to some extent self- sustaining via the heat of formation locally distributed.
The interface of plasma-anodized Hg1−xCdxTe
Authors: Nemirovsky Y. , Goshen R. , Kidron I.
Published: February 2003

The process for forming plasma-anodized oxide on Hg1−xCdxTe with x = 0.215 and 0.290 and the properties of the interface are studied. The results of Auger electron spectroscopy and x-ray photoelectron spectroscopy surface analytical characterization and the electrical interface characterization are compared with respective data on the interface between Hg1−xCdxTe and its solution anodized native oxide. The plasma oxide exhibits a decreasing gradient of oxygen and an increasing gradient of unoxidized tellurium from the surface towards the bulk semiconductor. An accumulation of fluorine at the interface unique to the plasma oxide is observed. Metal-Insulator-Semiconductor (MIS) devices with the plasma-anodized interface have a relatively low concentration of positive fixed surface charge density, (1–3)×1011 cm−2, and fast surface state density per unit band gap of about 2×1011 cm−2 eV−1, measured at 77 K. The hysteresis in the capacitance-voltage characteristics of the MIS devices is negligible, indicating the near absence of slow-trapping effects which have been observed in anodic solution oxides. Photoconductors passivated with plasma oxide exhibit good responsivity and detectivity, indicating small surface recombination velocity and small interface trapping. A significant advantage of the plasma oxide is the excellent thermal stability of the interface. Devices such as MIS capacitors and photoconductors may be annealed in vacuum up to 95 °C for prolonged periods while retaining their properties.
Electrical conductivity of III-V dislocated semiconductors
Authors: Penchina Claude M. , Farvacque J. L. , Masut Remo
Published: February 2003

We apply the generalized ’’energy loss method’’ to the case of many carrier conduction in III-V dislocated semiconductors by making use of the self-consistent occupation statistics of the whole energy spectrum. As an example we calculate the electrical resistivity of dislocated InSb samples containing ’’60°’’ or screw dislocations. Both the charge line and the piezoelectric scattering potentials are taken into account.
Annealing effects in tunnel junctions (voltage annealing with alternating polarity)
Authors: Konkin M. K. , Adler J. G.
Published: February 2003

This paper describes the time-dependent changes which occur in Al-Al oxide-Pb tunnel junctions as a result of voltage annealing with alternating polarity (AP). By examining changes in junction resistance, barrier parameters (barrier thickness, average barrier height, and the separation between barrier heights at the two electrodes), and inelastic electron tunneling (IET) peak intensities, one finds that some charge within the barrier is fairly mobile under the influence of AP voltage annealing while another portion appears to become trapped. Also, the IET intensity of the 118-meV Al–O stretching peak of the Al oxide was found to increase with decreasing barrier height.
Injected carrier lifetimes and double-injection currents in semiconductors with a single impurity level
Authors: Kuwano Hiroshi
Published: February 2003

Theoretical analyses of the lifetimes of injected electrons and holes, and the double-injection currents in long p-i-n diodes with a single impurity level, are treated by evaluating the space-charge density formed by the injection of the minority carrier lifetimes and the current-voltage characteristics are obtained in a low- and a high-injection regime, and approximately in an intermediate-injection regime, when the physical parameters of the i region and the dependence of the equilibrium majority-carrier density upon temperature have been measured beforehand.
Effects of oxide thickness on charge trapping in metal-nitride-oxide- semiconductor structures
Authors: Kapoor Vikram J. , Delatore James P.
Published: February 2003

Charge trapping in chemically vapor-deposited Si3N4 thin films of metal-nitride-oxide- semiconductor (MNOS) structures has been studied using the internal photoelectric-effect technique in combination with high-frequency capacitance-voltage measurements. The trapped charge density in the Si3N4 film was investigated as a function of the experimental parameters of the internal photoelectric-effect technique and the oxide thickness (300–20 Å) of the MNOS structure. The optimum trapped electron density in the Si3N4 film was measured to be 1.5×1018/ cm3 using 4.14-eV photon energy, 3.0-mW/cm2 light intensity, and −20-V applied gate voltage bias for the MNOS structures whose oxide thicknesses were greater than 70 Å. The photoinjection of holes from Si into Si3N4 was inhibited in thick-oxide (300–43 Å) MNOS structures due to the large barrier height at the Si-SiO2 interface. This eliminated simultaneous trapping of holes and electrons in the Si3N4 film. As the oxide thickness of the MNOS structure was reduced below the critical thickness of 43 Å, the photoinjection of holes from Si into Si3N4 was enhanced substantially with subsequent dominant hole trapping in the Si3N4 film.
Spin-wave instability threshold in single-crystal yttrium iron garnet for oblique pumping
Authors: Liu Y. H. , Patton C. E.
Published: February 2003

The spin-wave instability threshold hcrit for oblique pumping in high-quality single-crystal yttrium iron garnet (YIG) at room temperature and 9.317 GHz, has been examined. The experimental dependence of hcrit on the pump angle indicates that the microwave field components parallel and perpendicular to the dc field operate independently in exciting spin-wave instability. Theoretical fits to the data, based on this result, indicate that the spin-wave linewidth is strongly wave vector dependent and that the wave vector dependence varies with the pump angle.
Photoluminescence studies of 4He- and 9Be-implanted semi-insulating InP
Authors: Oberstar J. D. , Streetman B. G.
Published: February 2003

Low-temperature (5 °K) photoluminescence data on the annealing characteristics of both unimplanted and implanted (4He, 9Be) semi-insulating, Fe-doped (100) InP are presented. A rf plasma-deposited Si3N4 was used as the encapsulant during anneals. Annealing with this cap results in the appearance of a new spectral feature at 1.378 eV. For all samples examined here, high temperature (T?750 °C) anneals result in band-edge integrated intensities greater than in virgin material. This phenomenon is correlated with the appearance of the 1.378-eV peak. In samples implanted with 100 keV 9Be the band-edge peak is observed to shift to lower energies with increasing dose. Also, a new emission peak at 1.382 eV is shown to be associated with Be acceptors. The ionization energy of Be is estimated to be 41.3±3 meV. For 30-min anneals, maximum Be activation appears to occur for all doses at ∼750 °C. At this temperature, Be activation appears to saturate between 30 and 60 min.
Fluence dependence of displacement damage, residual defects, and electrical properties of high-temperature-annealed Se+-implanted GaAs
Authors: Bhattacharya R. S. , Pronko P. P. , Yeo Y. K. , Rai A. K. , Park Y. S. , Narayan J.
Published: February 2003

High resolution Rutherford Backscattering in combination with channeling and Transmission Electron Microscopy were used to study the fluence dependence of initial damage and residual defects of high-temperature (900 °C) Se+-implanted GaAs. It is found that the number of displaced atoms increases linearly as a function of dose, until the layer becomes amorphous. The damage profile extracted by using a single scattering theory is in good agreement with a Monte Carlo computer simulation when the ion dose is below that required to amorphize the layer. After annealing at 900 °C for 15 min, complete recovery of the damage has been observed for samples with 5×1012 cm−2 and 1×1013 cm−2. The samples with higher doses show some residual disorder which has been identified as dislocation loops and small precipitates. Electrical measurements reveal that highest activation efficiency is obtained for 1×1013 cm−2, which reduces drastically at higher doses. However, the activation efficiency for all doses increases with anneal temperature. The depth profile of the carrier concentration N showed that N is highest near the surface, decreases with increasing depth up to about 500 Å, and becomes nearly flat until it falls off near the substrate. The mobilities are found to be very low near the surface (<1000 cm2/ V sec), but they increase to larger values (≳3000 cm2/V sec) at some depth below the surface.
Oxygen-doped Pb-In-Au films suitable for Josephson tunnel junction base electrodes
Authors: Huang H.-C. W. , Murakami Masanori
Published: February 2003

The effects of oxygen doping during film deposition on film microstructures, surface morphology, strain behavior, and electrical resistivity have been studied by using transmission and scanning electron microscopies, x-ray diffraction, and electrical resistivity measurements for 0.2-μm-thick Pb and Pb-12 wt.% In-4 wt.% Au films prepared at ∼77 K. The average grain size of both types of films was found to decrease with increasing oxygen partial pressure during the film deposition: one order of magnitude smaller grains, compared with those prepared in a high vacuum (≲5×10−8 Torr), were obtained when the oxygen pressure was higher than 1×10−6 Torr. The finest average grain size obtained in the present experiments was ≲15 nm, which is over 10 times smaller than the film thickness. The surfaces of both films were found to be smooth when the films were prepared at oxygen pressures below 1×10−5 Torr. Strain relaxation upon cooling to 4.2 K was observed for oxygen-doped Pb films, but no strain relaxation was observed for Pb-In- Au films. In addition, no hillocks were observed in oxygen-doped Pb-In-Au films cycled 300 times between 300 and 4.2 K. The electrical resistivities of Pb-In-Au films were found to increase with oxygen pressure; an increase of a factor of 10 was observed when the films were prepared at an oxygen pressure of 1×10−5 Torr. The thermal cyclability of large-area Josephson tunnel junctions, in which oxygen-doped Pb-In-Au films were used as the base electrodes, exhibited the lowest cycling-induced failure level ever reported for large-area Pb-alloy Josephson tunnel junctions beyond 400 thermal cycles. The number of thermal cycles to reach 5% cumulative failure increased from 1000 to 5000 cycles by introducing 5×10−7 Torr of oxygen during film preparation at 77 K. However, the σ value (slope of the log normal failure distribution) becomes about three times larger.
Effect of screening singularities on the elastic constants of composition-modulated alloys
Authors: Wu Tai-Bor
Published: February 2003

A contribution to the unusual changes of the elastic constants of composition-modulated alloys can be obtained by extending the effects of screening singularities on the atomic pair potential following Krivoglaz and Moss. The formalism is presented, and the effect of the shape of Fermi surface on this elastic anomaly is discussed. Agreement is found between the theory and the observed enhancement of elastic moduli in foils with composition modulations. Predictions are offered as to which systems might produce large and small changes, if this is the major contributing factor.
Particle size effects in thick film resistors
Authors: Carcia P. F. , Ferretti A. , Suna A.
Published: February 2003

This paper describes the effect of conducting oxide particle size on the electrical conduction properties of thick film resistors based on finely divided Bi2Ru2O7 and Pb2Ru2O6. We show that the critical conduction behavior at low conducting oxide concentration can be described as percolative, and that the conducting threshold is lower for smaller particle size. We also measure an increase in the effective activation energies for the low-temperature resistivity, as the conducting oxide particle size decreases. This, we show, is consistent with a tunneling model for conduction in thick-film resistors.
Size dependence of the photophoretic force
Authors: Arnold S. , Lewittes M.
Published: February 2003

The photophoretic force on a micron-sized sphere of glycerol is measured for a continuously changing size parameter (through evaporation) for excitation at 10.63 and 9.58 μ. Although the force at 9.58 μ is always forward (’’positive’’ photophoresis), the force at 10.63 μ reverses in sign (’’negative’’ photophoresis) and shows a periodic structure in size parameter (2πR/λ) with a periodicity of 0.77±0.03. It is shown that the point of reversal may be used in obtaining the imaginary component of the refractive index. The possibility of solar levitation of atmospheric aerosols is discussed.
The geometrical correction factor for a rectangular Hall plate
Authors: Versnel W.
Published: February 2003

An analysis is given of a rectangular Hall plate with edge contacts of nonzero lengths, equal in size, two by two. The exact solution of the potential problem is obtained by means of Schwarz- Christoffel transformations. The numerical calculations involved can be reduced to those of regular integrals. In addition, for several dimensions of the rectangle, simple and accurate approximations have been derived for the product μB of Hall mobility and magnetic induction. Numerical data are tabulated in a directly applicable form so that a pocket calculator is sufficient to obtain the value of μB from measured data. It is indicated how Hall configurations with the same kind of symmetry can be analyzed.
Laser annealing effects in ion-implanted GaAs
Authors: Nojima Shunji
Published: February 2003

The annealing behaviors in Si ion-implanted GaAs, using a Q-switch-pulsed ruby laser, are characterized by a strong dose dependence of implanted-impurity concentration thus electrically activated; carriers are generated or not, according as the dose ranges ≳ or ≲1014 cm−2. To characterize this impressive phenomenon, four factors are presented, which seem possible as its origin: (1) Cr segregation, (2) laser irradiation defects, (3) insufficient laser energy absorption, (4) residual implantation damage. A detailed study denies factors (1)–(3) to be its origin. Factor (4) is decisive; implantation damage remains after laser annealing, as the damage-related localized states whose typical density is roughly estimated to be ∼1018 cm−3 or somewhat less. This result gives a satisfactory explanation for the above phenomenon. The fact that implantation damage remains is, however, suggestive of an annealing mechanism differing from the normal melting.
Photoluminescence study of acceptors in AlxGa1−xAs
Authors: Swaminathan V. , Zilko J. L. , Tsang W. T. , Wagner W. R.
Published: February 2003

A photoluminescence study of C, Si, Ge, Be, Mg, and Zn acceptors in AlxGa1−xAs is made. The binding energy of these acceptors is determined from the free-to-bound transitions at 75 K as a function of aluminum composition up to x∼0.4. It is observed that C, Be, and Mg behave like effective mass acceptors in AlxGa1−xAs while Si, Zn, and Ge show positive deviations from the effective mass theory with Ge exhibiting the maximum deviation. This difference in the behavior of the acceptors is suggested to be due to the difference in their central cell corrections in GaAs. The relative merits of these acceptors, in terms of their solubility, ionization energy, and diffusivity are considered. It is concluded that Mg is an attractive acceptor dopant in AlxGa1−xAs grown by liquid phase epitaxy.
Addendum: New model of electron free path in multiple layers for Monte Carlo simulation
Authors: Hawryluk R. J. , Hawryluk A. M. , Smith H. I.
Published: February 2003

In this note, it is shown that the previous Monte Carlo simulations of energy dissipation in polymer films by electron beam scattering [R. J. Hawryluk, A. M. Hawryluk, and H. I. Smith, J. Appl. Phys. 45, 2551 (1974)] are consistent with the recent calculation of S. Horiguchi et al. [Appl. Phys. Lett. 15, 512 (1981)]. Such Monte Carlo simulations have been widely used in electron beam lithography.
Degradation mechanism of zinc oxide varistors under dc bias
Authors: Hayashi Masahiko , Haba Masanori , Hirano Shinji , Okamoto Masako , Watanabe Misuzu
Published: February 2003

The degradation mechanism of ZnO varistors under dc bias is investigated from the viewpoint of the time dependence of leakage current under dc biasing, the voltage-current characteristics, and the thermally stimulated current and dielectric properties before and after dc biasing test. The experimental results are analyzed on the basis of the Schottky barriers which control current transport in varistors at the grain boundary regions. The increase in leakage current is expressed as J = A exp (Bt0.3) ( J is the leakage current; A and B are constants, and t the biasing time) and is attributed to the deformation of the Schottky barriers. The deformation corresponds to the lowering of the barrier height and decrease in the depletion width. This is due to the uneven distribution of positive charges caused by the migration of donor ions. In case of the degradation of varistors under long term dc bias, the deformation is mainly due to decrease in the depletion width. Taking into account the electric field due to positive charges and the skew of Fermi level, etc., the asymmetrical deformation can be also explained as a phenomenon due to surplus positive charges, formed in the reverse-biased depletion layer.
Plasma-enhanced chemical vapor deposited SiO2/InP interface
Authors: Wager J. F. , Wilmsen C. W.
Published: February 2003

Plasma-enhanced chemical vapor deposited (PECVD) SiO2 using silane and nitrous oxide has previously been used to fabricate metal insulator semiconductor field-effect transistors (MISFETs) and MISFET integrated circuits on InP. These devices exhibit hysteresis in their curve-tracer characteristics and drift in the MISFET drain current. The inversion layer electron mobility is also known to vary from sample to sample. These electrical characteristics may be caused by an interfacial oxide. This paper presents x-ray photoelectron spectroscopy (XPS) depth profiles of the PECVD SiO2/InP interfacial region for various in situ processing. The depth profiles indicate that a native InP oxide is present at all the PECVD SiO2/InP interfaces and that the thickness and composition of the oxide is relatively independent of the in situ chemical treatments. This native oxide appears to be a plasma grown InPO4 with a thickness in the range of 10–25 Å. The composition and topography of air, thermal, and plasma grown oxides without SiO2 deposition were also investigated with XPS and transmission electron microscopy (TEM). For very thin layers, all of these oxides were found to have a similar phosphate composition which is probably InPO4. As the oxide became thicker, the outer layer became depleted of phosphorus and appeared to be primarily In2O3. The topography of the plasma grown oxides was observed to be rougher than that of the thermal or air grown oxides. This roughness could contribute to the reduction of inversion layer mobility.
Self-field effects in superconductor-normal metal-superconductor junctions
Authors: Nagata Shoichi , Yang H. C. , Finnemore D. K.
Published: February 2003

The temperature dependence of the dc Josephson critical supercurrent has been measured for square lead-zinc-lead (superconductor-normal metal-superconductor) junctions in order to make a quantitative study of self-field effects. Correction for the critical current density, Jc, due to the self-field effect is made by using the linearized two-dimensional model proposed by Vaglio. We calculate the temperature dependence of the Josephson penetration depth, λJ and find Jc to be proportional to (1−T/Tc)2 in the range where λJ is comparable to the junction width, W.
Effect of boundary conditions upon the phase distribution in two- dimensional Josephson junctions
Authors: Barone A. , Esposito F. , Likharev K. K. , Semenov V. K. , Todorov B. N. , Vaglio R.
Published: February 2003

A detailed theoretical analysis and careful experimental measurement of the phase distribution of two-dimensional Josephson junctions are reported. The current density distribution along the junction contour, which provides the boundary conditions of the problem, is obtained through analog modelling by the electric field distribution in an electrolytic bath. The dependence of the critical supercurrent upon the applied magnetic field has been considered for square cross-type junctions. The experiments performed on Nb-NbxOy-Pb samples confirm unambiguously all the peculiar features predicted by the theoretical analysis.
Charged wall formation and propagation analysis in ion-implanted contiguous disk bubble devices
Authors: Hidaka Y.
Published: February 2003

Magnetic anisotropy energy along a pattern edge is found to be important for charged wall formation at the pattern edge in ion-implanted contiguous disk bubble propagation track. Charged wall formation and propagation are found to be little affected by the demagnetizing effect at the pattern edge. Charged wall formation and propagation mechanisms are well explained on the basis of the Stoner-Wohlfarth magnetization reversal model, taking into consideration magnetic anisotropy energy along the pattern edge.
Electrical breakdown of insulators by one-carrier impact ionization
Authors: Klein N.
Published: February 2003

Theories for current runaway by one-carrier impact ionization are generalized for insulators, in which the injected and ionizing charge carrier type is subject to trapping. Relations are derived for the critical current runaway field Fr and time to breakdown tr , and written in simple forms, offering physical insight into breakdown processes. A trapped charge of injected carriers is frequently established in the insulator, before a current runaway process develops. The breakdown relations show that the effect of such a trapped charge can be a significant increase in Fr and tr , as observed in several inorganic and organic insulators. The trapped charge is not always established on fast ramp tests. In such cases an anomalous range is predicted and observed in the breakdown characteristics, in which the breakdown field diminishes with decreasing time to breakdown. Breakdown models developed here will be found in the companion paper to offer consistent interpretations for observations on aluminum oxide.
Particle deposition in a burner
Authors: Gourdin William H. , Andrejco Matthew J.
Published: February 2003

The flame deposition of colloidal silica particles onto a collector has been characterized for a simple, cylindrically symmetric geometry. Material is deposited over a limited area of a disk and the individual particle paths form an inverted cone which can be observed to penetrate the boundary layer at the disk surface. The paths emanate from a narrow stream confined close to the axis of the flow. A model is proposed to qualitatively explain the collection process and account for observed behavior. This comparatively simple approach apparently contains the essential features of the process. The general form of the deposition is determined by inertial forces on the particles. Impaction, however, is due to forces which result from moderate thermal gradients near the collector surface. A critical radius exists, depending upon conditions of temperature and flow, beyond which deposition does not occur. Although the model provides a generally unsatisfactory description of the flux distribution, it is apparent that the flux will be a maximum off center, resulting in a depression in the center of the collected material. Deposition at the stagnation point is a special case, beyond the scope of this model.
Computer molecular-dynamics studies of grain-boundary structures. I. Observations of coupled sliding and migration in a three-dimensional simulation
Authors: Bishop George H. , Harrison Ralph J. , Kwok Thomas , Yip Sidney
Published: February 2003

Methods of computer molecular dynamics have been applied to model a 𝒥 = 5 symmetric-tilt coincidence grain boundary. A pairwise Lennard-Jones 6–12 potential was used to simulate the atomic interactions in a bicrystal containing up to 396 atoms. At simulated temperatures of approximately half the potential well depth the boundary undergoes spontaneous sliding coupled with migration. The observations are consistent with a geometrical model based on the coincidence model of grain boundaries and also with the results of a separate calculation of the Peierls-Nabarro-like energy barrier for such coupled sliding and migration, using a static relaxation method on a model constrained to have various displacements.
The wavelength modulation spectrum of ion-implanted silicon
Authors: Lue J. T. , Shaw S. Y.
Published: February 2003

The radiation damage and its subsequent annealing in phosphorus implanted Si are studied by wavelength modulation spectroscopy. The distinct structure at λ = 360 nm of the wavelength- derivative spectrum is implemented as a parameter to specify the damage level in Si crystals. This characteristic peak completely fades away when the implanted dose exceeds 3×1015 ions cm−2. Isochronal and isothermal annealing indicate that the removal of vacancy-like defects starts at rather low temperatures (∼200 °C) while the recrystallization of the disordered layer starts at a temperature near 500 °C. Sheet resistance of the samples measured by a four-point probe has been found to be closely related to the wavelength modulation spectrum.
The material state of ion-implanted Cr in GaAs
Authors: Pronko P. P. , Rai A. K. , Holland O. W. , Appleton B. R. , Narayan J.
Published: February 2003

Chromium-implanted GaAs has been studied using 120 keV implants to fluence levels from 1×1014 to 5×1016 cm−2. The postannealed materials state has been examined using Rutherford backscattering spectrometry, proton-induced x-ray excitation, channeling, and transmission electron microscopy. Annealing was performed in flowing H2 at 900 C for 15 min under 85-nm thick Si3N4 dielectric caps. Various stages of precipitation were observed having structure and composition that depended on total implanted fluence. For the highest fluence, coarse nonuniform second-phase precipitates were present with dimensions on the order of 50 to 100 nm. At lower fluences small defect cluster precipitates, with average diameters of 6 nm, were identified through black-white contrast analysis. The relative fraction of precipitated Cr was 40% at 1×1015 cm−2 and decreased to 9% at 5×1014 cm−2. The volume concentration of implanted Cr that is retained in solid solution after annealing is estimated at 2×1018 cm−3. Channeling analysis suggests that these atoms are retained in nonunique interstitial or other nonsubstitutional positions.
Hydrogen content of a variety of plasma-deposited silicon nitrides
Authors: Chow Ray , Lanford W. A. , Ke-Ming Wang , Rosler Richard S.
Published: February 2003

The hydrogen contents and etch rates have been measured for plasma-deposited silicon nitrides made in nine different commercially available reactors as well as for some low pressure chemical vapor deposited nitrides. The hydrogen contents vary from 4% to 39% (atomic). A correlation is observed between etch rate and hydrogen content, with etch rates varying over three orders of magnitude.
Determination of dynamic fracture parameters for HF-1 steel
Authors: Mock Willis , Holt William H.
Published: February 2003

Dynamic fracture parameters have been determined for two heat treatments of HF-1 steel. A gas gun was used for the experiments. Different amounts of fracture damage were produced in HF-1 steel specimens under known impact conditions. The specimens were soft recovered, sectioned, and polished to reveal any internal microscopic fracture. The fracture cracks were then digitized. The velocities of the 1.15-, 1.59-, and 2.37-mm-thick impactor disks range from 0.120 to 0.276 km/s. The specimen disks were 3.18- and 6.35-mm thick. An SRI stress wave propagation computer program with a brittle fracture model was used for calculating the dynamic fracture parameters. A series of Hugoniot experiments was performed for HF-1 steel to determine equation of state input data for the computer program. The Hugoniot elastic limits were 2.2 and 2.4 GPa for the two heat treatments.
X-ray diffraction from high pressure Ge using synchrotron radiation
Authors: Baublitz M. , Ruoff A. L.
Published: February 2003

The high pressure structural phase transition in Ge has been studied using the energy dispersive x- ray diffraction technique and a synchrotron radiation source. Ge was observed to transform to the β-Sn tetragonal structure in agreement with the earlier results of Jamieson, but the phase transition began at 80±5 kilobars, a somewhat lower value than generally reported. These experimental diffraction results are compared with the recent self-consistent pseudopotential calculations of Yin and Cohen and with the observed transition pressure for shock wave loaded Ge.
Grain-boundary diffusion in some Pb-Sn alloys
Authors: Oberschmidt J. , Kim K. K. , Gupta D.
Published: February 2003

We report the results of grain-boundary diffusion measurements for Pb and Sn tracers in Pb1−xSnx alloys where x = 1.7, 3.5, and 8.3 at. %. We also report results for lattice diffusion in these alloys. The low temperature results for the 8.3% alloy are particularly interesting, because precipitation or dissolution of Sn may occur at low temperatures during the diffusion anneal depending on the history of the sample. The variation of the grain-boundary diffusivities for the Pb and Sn tracers measured during simultaneous dissolution or precipitation was small. However, the Sn diffusivities in the dissolution case were consistently lower than the corresponding equilibrium values. There may be several possible causes for this effect. One reflects the inapplicability of the Whipple analysis, which is generally used to obtain the diffusivity because of the migration of grain boundaries, and the other is that this result is due to the reduction of the number of vacant sites in the grain boundary by Sn precipitates. We believe that the former is the most likely explanation.
An analysis of solitons in surface acoustic wave devices
Authors: Ewen J. F. , Gunshor R. L. , Weston V. H.
Published: February 2003

Recently, in the area of mathematical physics, there has been a growing interest in nonlinear, dispersive systems, and particularly in solitons, a type of wave which exists as a balance between the nonlinearity and the dispersion. There are two basic types of solitons, one of which is a baseband, pulse-like signal, and the other consisting of a rf pulse in which the envelope exhibits soliton behavior. In both cases the soliton behavior is characterized by the stable propagation of the signal in the presence of nonlinearity and dispersion. All surface acoustic wave (SAW) devices exhibit dispersion and nonlinearity to varying degrees. The purpose of this paper is to relate the rapidly growing developments in soliton theory to the SAW device field. Computer simulations of a phenomenological model identify various parameters which characterize the development of an initial condition into solitons. A number of SAW device configurations are evaluated in the context of the phenomenological model for the possibility of soliton propagation.
Properties of CdTe-Te alloy films prepared using molecular beams
Authors: Myers T. H. , Waltner A. W. , Schetzina J. F.
Published: February 2003

A series of CdTe-Te alloy films was prepared by molecular beam deposition in an ultrahigh vacuum. This allowed precise and systematic variation of the Cd/Te vapor flux ratio during growth which produced films whose resistivity varied by more than eleven orders of magnitude. The electrical, structural, chemical, optical, and surface properties of these CdTe-Te alloy films are discussed.
Improved varistor nonlinearity via donor impurity doping
Authors: Carlson W. G. , Gupta T. K.
Published: February 2003

Zinc oxide (ZnO) varistors exhibit a voltage upturn at higher current densities which reduces their effectiveness as over-voltage protection devices. This effect has been attributed to a limiting series impedance offered by the ZnO grains. Based on literature data, the varistors were made for this investigation wherein the grain impedance has been reduced by doping with Al2O3 or Ga2O3. The high current surge and high frequency impedance data combined with microstructural investigation indicated an improved varistor nonlinearity via donor doping. A simple defect model developed for a pure ZnO crystal has been used to explain the doping behavior of the varistor grain.
Quantitative study of recurrence in Korteweg de Vries systems
Authors: Wedding Berthold , Jäger Dieter
Published: February 2003

The dispersion and amplitude dependence of the recurrence phenomena in Korteweg de Vries (KdV) systems is examined both theoretically and experimentally. In a first theoretical analysis the coupled propagation of two harmonic waves is regarded. The second treatment is based upon a mathematical description of two propagating KdV solitons including the phase shift due to the interaction process. It is concluded that this phase shift reveals an important influence on the recurrence length. Finally, the theoretical results are compared with experimental data from measurements performed on LC transmission lines and with numerical solutions of the KdV equation. An excellent agreement is obtained for a large range of the nonlinear index of the normalized KdV equation.
Thermodynamic limits to the conversion of blackbody radiation by quantum systems
Authors: Buoncristiani A. M. , Byvik C. E. , Smith B. T.
Published: February 2003

Using general thermodynamic arguments, we analyze the conversion of the energy contained in the radiation from a blackbody to useful work by a quantum system. We show that the energy available for conversion is bounded above by the change in free energy in the incident and reradiated radiation fields and that this free energy change depends upon the temperature of the receiving device. Universal efficiency curves giving the ultimate thermodynamic conversion efficiency of the quantum system are presented in terms of the blackbody temperature and the temperature and threshold energy of the quantum system. Application of these results is made to a variety of systems including biological photosynthetic, photovoltaic, and photoelectrochemical systems.
Electron momentum modulation by the stimulated Cerenkov interaction
Authors: Kimura W. D.
Published: February 2003

Momentum modulation of relativistic electrons by laser light using the stimulated Cerenkov interaction is analyzed. This interaction is accomplished by introducing a gas whose index of refraction retards the phase velocity of the light wave. By intersecting the electron and laser beams at the Cerenkov angle, ϑc = cos−1(1/nβ), where n is the index of refraction of the gas, and β is the ratio of the electron velocity over the velocity of light in vacuum; the electrons remain in a field of constant phase resulting in a cumulative energy exchange. The laser-induced change in particle momentum and the electron beam energy spectrum are analyzed as a function of the electron and laser-beam characteristics. The results agree with a computer simulation of the interaction.
A study of cathode edge emission
Authors: Zhao Yong-xiang
Published: February 2003

A great deal of experimental evidence shows that the perveance of high-power klystrons is much higher than normal at low voltage. Thus the three-halves power law is violated in that range. It is hypothesized that this is caused by edge emission. A detailed analysis is given. The calculated magnitude is reasonably coincident with experimental results. The analysis is also valid for other thermionic tubes.
Measurements of acoustic properties for thin films
Authors: Kushibiki Jun-ichi , Maehara Hiroyuki , Chubachi Noriyoshi
Published: February 2003

A measurement method for determining thin-film acoustic properties, such as characteristic acoustic impedance, sound velocity, density, and stiffness constant, is developed with a simple measurement principle and high measurement accuracy. The acoustic properties are determined from a maximum reflection loss and a center frequency obtained through a frequency response of the reflection loss for an acoustic transmission line composed of a sapphire/film/water system by using the acoustic pulse mode measurement system in the UHF range. The determination of the acoustic properties is demonstrated for sputtered fused quartz film, low-expansion borosilicate glass films, and chalcogenide glass films of evaporated As2S3 and As2Se3, within the measurement accuracy around 1–2%. It is also found that the acoustic properties of thin films are generally different from those of bulk materials, depending on the fabrication techniques and conditions.
The dynamics of imploding argon plasmas
Authors: Clark W. , Richardson R. , Brannon J. , Wilkinson M. , Katzenstein J.
Published: February 2003

The BLACKJACK 5 pulse generator has been used to implode annular argon plasmas to form dense Z pinches. Visible streak photography, framing photography, and laser shadowgraphy were used to observe the radial position and velocity of the plasmas as they imploded. The measured position and velocity of the imploding plasmas have been compared with the results of calculations based on a one-dimensional snowplow model. Good agreement is obtained between the snowplow calculations and the optical measurements. Empirically determined optimum implosion parameters are also found to agree with those predicted by the model.
On conditioning: Reduction of secondary- and rf-field emission by electron, photon, or helium impact
Authors: Halbritter J.
Published: February 2003

rf conditioning is a well known procedure by which the electron emission in rf cavities is reduced, thereby permitting the attainment of higher field strengths. The reduction of electron emission in rf conditioning is explained by electron, photon, or He impact, which causes hydrocarbon adsorption and dehydrogenation and polymerization of adsorbed hydrocarbons. These newly formed radiation-resistant compounds show strong inelastic scattering for slow electrons, which greatly reduces the secondary emission and field emission out of excited states (rf-field emission).
Hydrogenated amorphous silicon growth by CO2 laser photodissociation of silane
Authors: Bilenchi R. , Gianinoni I. , Musci M.
Published: February 2003

A new method of hydrogenated amorphous silicon deposition on large areas is reported in which silane is photodissociated by resonant absorption of cw CO2 laser radiation. The free radicals produced interact in a suitable geometrical configuration with the surface of a low-temperature substrate and grow a film having properties similar to the glow-discharge deposited material. The film amorphousness and the hydrogen presence either in monohydride and dihydride groups are evidenced by x-ray patterns and ir spectra.
Deep uv submicron lithography by using a pulsed high-power excimer laser
Authors: Kawamura Y. , Toyoda K. , Namba S.
Published: February 2003

Deep uv lithography by using a pulsed high-power excimer laser is demonstrated, in which submicron patterns with high resolutions were fabricated on PMMA (polymethyle methacrylate) photoresists by laser irradiation for 20 ns.
Some unexpected equilibrium and transport properties in indium-doped silicon
Authors: Cappelletti P. , Cerofolini G. F. , Pignatel G. U.
Published: February 2003

Anomalies concerning the expected values of resistivity and mobility of indium-doped silicon in the range where hole scattering is dominated by ionized impurities have been observed. These anomalies can be removed assuming a value of hole effective mass in agreement with the hydrogenlike model of shallow impurities in semiconductors. This suggests a reanalysis of the current picture of hole transport properties in moderately doped semiconductors.
Magnetic domain structures and domain walls in iron fine particles
Authors: Sato Masayoshi , Ishii Yoshihiro , Nakae Hitoshi
Published: February 2003

In order to estimate the critical particle size lc for a single domain structure, the magnetic energy densities of an iron fine particle are calculated as a function of the particle size for various configurations of magnetization. It is assumed in this calculation that in a small particle the energy of a domain wall consists of the exchange, anisotropy, and magnetic stray field energies. It is found that lc is 20 nm for a particle with an axial ratio of n = 1, increases with an increase in n, and is 60 nm for a particle with n = 10. The wall energy of a fine particle is found to be much larger than that of bulk material owing to the stray field energy. Due to this wall energy, the magnetization configuration is the circular configuration of spins for the particle with a size larger than lc , and it becomes the flux closure configuration by four domains for the particle with a size larger than 900 nm if n = 1 and 600 nm if n = 10.