bluuebunny/crossref_metadata_2025 huggingface dataset:
Dislocation propagation and emitter edge defects in silicon wafers
Authors: Hu S. M. , Klepner S. P. , Schwenker R. O. , Seto D. K.
Published: February 2003

Some transistor defects show a tendency to occur near the edges of emitters. Like ’’area defects’’, these ’’edge defects’’ occur in silicon wafers in a distribution pattern reminiscent of thermal-stress-induced dislocations. A peculiar feature is that often a number of edge defects which are close replicas of one another occur in a string, each in one of the neighboring emitters. Such edge defects are preponderant in transistors having silicon nitride surface films. In our proposed model, these emitter edge defects are generated when thermal-stress-induced dislocations glide through a row of emitters and interact with the emitter edge stresses, thereby, and under appropriate conditions, casting off small dislocation half-loops which straddle the edges. The model is shown to be consistent with all the observed phenomena pertaining to the emitter edge defect. To provide a foundation for the discussion of the finer details of the emitter edge defects, we also present an analysis of the nature and distribution of thermally induced dislocations, itself a topic of general interest.
Influence of the growth condtions on the incorporation of deep levels in VPE GaAs
Authors: Humbert A. , Hollan L. , Bois D.
Published: February 2003

Vapor-phase epitaxial (VE) n-type GaAs layers have been grown through the classical Ga/AsCl3h2 method unde different growth conditions. The AsCkl3 mole fraction X and the source and deposition temperatures have been changed separately. The variation of the growth rate τ of the layers versus X shows that two growth regimes occur: for small values of X, τ increases with X, while it decreases at highe values. This clearly demonstrates that the growth is limited by kinetic effects. In both regimes, for undoped materials, the residual free-carrier concentration nT* is very sensitive to the growth parametes. In undoped layers, nnT* varies like the growth rate in the first growth regime, i.e., for small X. For the highest values of X, NT* decreases like n:NT* appears to be proportional to ND, i.e., to SiGa. Intentional doping of the layers with sulphur leads to an increase of nT*. Again, NT* is proportional to the sulphur concentration. The origin of the involved defect is discussed. According to these experiments and to the literature it appears that a complex involving a vacancy and a donor atom might be responsible for all the observed variations.
Composition dependence of the AlxGa1−xSb energy gaps
Authors: Bedair S. M.
Published: February 2003

Photoresponse measurements were made to determine the compositional dependence of the AlxGa1−xSb direct and indirect energy gaps. Three different valence-to-conduction-band transitions have been identified, with threshold energies of 0.69, 0.77, and 1.11 eV for GaSb, and 1.51, 1.75, and 2 eV for AlSb. The direct conduction-band minimum is found to be the lowest conduction-band minimum in the composition range 0?x<0.25.
Excitation of cavity modes in rectangular Josephson junctions
Authors: Nerenberg M. A. H. , Forsyth P. A. , Blackburn J. A.
Published: February 2003

The I-V characteristics of rectangular self-resonant Josephson junctions are derived in the weak-coupling limit for arbitrary magnetic field orientations. It is found that in general the full set of cavity modes should be excited. The behavior of a quasi-one-dimensional strip-line junction is then seen to be simply a special case of the above result.
Superconducting Nb3Sn cavities with high quality factors and high critical flux densities
Authors: Hillenbrand B. , Martens H.
Published: February 2003

As considerable progress is expected to result from the use of high-Tc superconductors at microwave frequencies, we started a study of the microwave properties of Nb3Sn. Preparation was done by exposing niobium cavities to a saturated tin atmosphere. Microwave measurements of the unloaded quality factor Q0 and the critical flux density Bacc were performed in the TE011 mode at 9.5 GHz. At 1.5 K low-field values of Q0 up to 6×109 and Bacc values up to 100 mT with a Q0 of 2.3×109 were obtained. At 4.2 K and at low magnetic flux densities a Q0 of 2.7×109 was reached.
Some implications of domain-wall flexibility on the interaction with dislocations and the existence of hysteresis
Authors: Baldwin John A. , Milstein Frederick
Published: February 2003

The theory of the force of interaction between a dislocation (or defects) and a rigid planar magnetic domain wall is extended to cover the case of a flexible wall. There is considerable difference between the two forces. In particular, the interaction loss due to a single dislocation is demonstrated. Hysteresis loss is due to biscous damping. As such, it is not strictly separable from eddy-current loss. Consequently, wall flexibility may not be ignored in the study of hysteresis. A scheme for magnetically classifying dislocations is developed. Using the force of interaction with a single dislocation, expressions are derived for the pressue due to a random distribution of N dislocations per unit volume versus average wall position. This is, in general, not a linear relation and also depends on whether the dislocation is attactive or repulsive. The relations derived permit a more detailed comparison between experiment and the theory of interaction between dislocations and domain walls. The primary purpose of this work is to provide the first step to a means for comparing the results of theoretical calculations of interaction force with experiment.
Thin-film thermal-profile measurements by means of distant-focused infrared radiometry
Authors: Koert Peter , Jones Roger C.
Published: February 2003

By suitable additions to an archaic military infrared radiometer, a distant-focused infrared radiometer system was constructed. Then, from a distance of more than 3m from the primary mirror, thermal-profile data on tapered thin-film aluminum strips were taken, with a resolution of 0.032 cm. The modified radiometer system was calibrated carefully and an independent measurement of the thermal emissivity of thin-film aluminum was made. The thermal-profile data were utilized in an associated project with good results.
Normal modes of semiconductor p-n–junction devices for material-parameter determination
Authors: Lindholm Fredrik A. , Sah C. Tang
Published: February 2003

An expression for the dominant normal model (natural frequency) of a p-n–junction diode is derived. The expression includes the effects of minority charge in the quasineutral emitter as well as the base region, and is applicable for any concentration profiles of impurity and recombination centers, regardless of high recombination rates or band-edge distortion in the emitter. Its use enables the experimental determination of material parameters pertaining to the relative roles of the emitter and the base in governing the behavior of various junction devices, including diodes, transistors, and solar cells.
Studies of radiative absorption at KCl surfaces using acoustic techniques
Authors: Rockwell D. A. , Parks J. H.
Published: February 2003

The application of an acoustic technique to measure surface radiative absorption in highly transparent materials is presented. Dispersive phase changes in acoustic surface wave propagation are induced by the absorption of 10.6-μm pulsed laser radiation on KCl surfaces. Analysis based upon an absorbing surface layer model provides a ±15% determination of both the total surface absorption σ=4.5×10−4 and a bulk absorption coefficient βB=2×10−3 cm−1 for a mechanically polished/chemically etched surface. After mechanical repolishing, this sample yields σ=11.3×10−4. The sensitivity of this technique indicates the possibility of measuring a surface absorption as small as σ≲10−5 and also obtaining details of the radiative absorption depth distribution.
Transient response of a cold plasma half-space in the presence of a transverse static magnetic field
Authors: Stanić Božidar V. , Škorić Miloš M. , Cander Ljiljana R.
Published: February 2003

The reflection of a normally incident linearly polarized impulsive plane wave by a cold homogeneous lossess plasma half-space with a constant magnetic field parallel to the interface is examined. By the use of a perturbation method the expression for the transient reflected field is given in a close form. Good agreement between the perturbation solution and results computed by the use of the numberical inverse Fourier transform is obtained for the values of the ratio of the electron cyclotron and electron plkasma frequency αc=ωc/ωp less than 0.3. Using the convolution integral, the transient response for the unit setp and rectangular incident pulse is given in a closed form.
Structure simulation of transition metal-metalloid glasss
Authors: Boudreaux D. S. , Gregor J. M.
Published: February 2003

Procedures are efficient numerical simulation.of multicomponent alloy glasses, using the concept of dense random packed (DRP) hard spheres, are described in detail. Methods of statistical analysis are discussed and applied to several simulated structures of transition-metal (TM) –metalloid (M) glasses. The pair correlations in DRP models using the conventional approach are found to be highly anisotropic and are concluded to be the cause of the varying density in these structures. Statistical data appropriate to Fe-P and Pd-Si glasses are analyzed and discussed for the compositional range from TM73 M27 to Tm100. Certain structural features appear only near the 80/20 (atomic percentages) composition common to numerous stable glasses.
Annealing characteristics of highly P+-ion-implanted silicon crystal—two-step anneal
Authors: Uda Keiichiroh , Kamoshida Mototaka
Published: February 2003

Single-step and double-step annealing behavior of highly P+-ion-implanted layers was investigated by means of four-point probe measurements, x-ray double-crystal spectrometry, and electron diffraction patterns. The x-ray double-crystal spectrometry data indicated that, in the case of single-step annealing, the layer implanted with doses lower than 3×1015/cm2 ions was recovered with the increase of annealing temperature, while the sample implanted with doses of 1×1016/cm2 ions showed the opposite behavior. That is, the latter sample showed a very bad recrystallized layer with polycrystalline regions when it was annealed at temperatures higher than 1000 °C. However, in the case of double-step annealing, the higher-temperature annealing process, conducted after long 560 °C annealing, made it possible to obtain a good recrystallized layer, compared with the single-step annealing case. These results were confirmed by electron diffraction patterns.
Arc durations as a function of contact metal and exposure to organic contaminants
Authors: Gray Eoin W. , Uhrig Thomas A. , Hohnstreiter Glenn F.
Published: February 2003

Activated-break arc durations have been measured for various organic compounds and contact metals. These durations were determined as a function of exposure (partial pressure of organic contaminant times the contact open time) for each metal and organic compound. The metals studied were palladium, gold, silver, rhenium, 60 Pd-40 Ag, and 73 Pd-27 Ni (wt%). Organics used were diethylphthalate, isopropyl alcohol, trichlorotrifluoroethane (Freon 113), benzene, n-hexane, cyclohexane, and phenol. The experimental results show three separate regimes with respect to exposure and agree well with the previous models of contact activation which have been generalized to include constant arc durations at short exposures. The steady-state average arc duration, which is proportional to contact erosion, was found to be a function of both the contact material and exposure for a particular organic material. The data has been statistically analyzed and the results indicate that in the adsorption-site-limited regime (high exposure) the metals can be divided into groups according to their activation susceptibility, while the organic materials all belong to a single group. In the diffusion-limited regime (intermediate exposure) ranking was observed for both the metals and organics, with larger differences noted for the organics. Finally in the initial activation region (low exposure) the individual differences between the organic or metal effects cannot be distinguished to 95% confidence. However, the degree of activation of a specific metal-activant pair can be quite different than that expected from the average behavior of the metal over all activants, and the average behavior of the activant over all metals. Thus the metal-activant pair is critically important in establishing the degree of activation.
Rise time and time-dependent spark-gap resistance in nitrogen and helium
Authors: Sorensen T. P. , Ristic V. M.
Published: February 2003

The rise time and time-dependent spark-gap resistance in nitrogen and helium were measured using a novel microwave method. Empirical formulas for spark-gap resistance and rise time are proposed, with a maximum error, as compared to experimental results, of ±8%.
Measurements of large ion currents in a pinched relativistic electron beam diode
Authors: Swain D. W. , Mix L. P. , Kruse L. W. , Poukey J. W.
Published: February 2003

We have observed ion currents of 10–20% of the total diode current in a diode exhibiting pinched electron flow. Measurements have been made utilizing two independent techniques—multiple Faraday cups, and neutron generation and counting. The results agree well with each other and are compared with both numerical simulations and an analytic model of ion flow. Agreement is found to within the accuracy of the experimental measurement, lending further credence to the theoretical models.
Axial cataphoresis effects in continuously pulsed copper halide lasers
Authors: Liu C. S. , Feldman D. W. , Pack J. L. , Weaver L. A.
Published: February 2003

It has been observed in a continuously pulsed copper halide laser that laser performance deteriorates rapidly due to axial cataphoresis effects. Dissociated copper ions are pumped cataphoretically toward the cathode by the applied electric field, causing nonuniform laser discharges and preferential copper condensation near the cathode. These effects can be eliminated experimentally by alternating the polarity of the applied voltage either mechanically or electronically. This improvement permits long-lived copper halide laser operating at average power levels in the 1–10-W range.
Blue electroluminescence from ZnSe diodes
Authors: Yamaguchi Masafumi , Yamamoto Akio , Kondo Mamoru
Published: February 2003

ZnSe p-n junction diodes have been formed by nitrogen ion implantation. MIS diodes have also been made using a film of ZnSe oxidized in H2O2 solution for the insulator layer. Blue electroluminescence has been observed from both the diodes in forward bias at room temperature. The external quantum efficiency is about 10−5. The emission may originate from a bound exciton.
Polarization and dielectric constant of SrTiO3 glass ceramics at low temperatures
Authors: Siegwarth J. D.
Published: February 2003

Peaks observed in the temperature dependence of the dielectric constant of SrTiO3 glass ceramics do not appear in the dc polarization. A remanent polarization is observed between 4 and 77 K. The dielectric properties at low temperature are attributed to the relaxation of permanent dipoles to an electret state rather than to antiferroelectric ordering.
Interference method of accurate determination of the relative magnitude of nonlinear optical coefficients
Authors: Okada Masakatsu , Takizawa Kuniharu , Ieiri Shogo
Published: February 2003

A method for accurate determination of the relative magnitude and sign of nonlinear optical (NLO) coefficients is described. It is based on the interference between optical second harmonic (SH) signals generated in two crystals and involves measurements of the maximum and minimum in the interference by changing the spacing between two crystals. This interference method allows one to determine more accurately the relative magnitude of NLO coefficients in the case that two SH signals are closer to each other, and may be especially suitable for observation of a small change of a NLO coefficient or a small difference between NLO coefficients. We have applied this method to measure the relative magnitude of NLO coefficients d14 and d36 of KDP, which are taken to be equal by Kleinman’s symmetry relation, and found that d14/d36=1.064±0.008 at the fundamental wavelength of 1.064 μm.
Dielectric, elastic, and electro-optic properties of a liquid crystalline molecular complex
Authors: Park J. W. , Labes M. M.
Published: February 2003

The dielectric and elastic constants as well as the electro-optic response times of twisted nematic cells of the binary liquid crystalline system N- (p-methoxybenzylidene) -p-n-butylaniline (MBBA)/4-cyano-4′-pentylbiphenyl (CPB) were studied. The formation of a molecular complex between MBBA and CPB leads to wide mesomorphic ranges and higher dielectric anisotropies, as well as favorable rise and decay times. This latter effect is mainly due to relative decreases in viscosity at a given temperature associated with elevation of the nematic-isotropic transition temperature.
Cataphoretic distributions of Co, Ni, and Mn in metal-halide–He discharges
Authors: Cross Lee A. , Funk Loren L.
Published: February 2003

Longitudinal emission intensity measurements for the metals Co, Ni, and Mn in the gas phase in a positive column He discharge tube, where the source of the metal is the corresponding metal chloride contained in a conventional appendage reservoir, have been made. The conditions of the discharge were similar to those of a typical metal vapor laser and concentrations of these nonvolatile metals achieved which are comparable to the positive column lasers. The longitudinal dependence of the Cl+ and various metal atom concentrations illustrates that they are strongly bound together by chemical recombination occurring on the wall of the bore. The failure of such a system to maintain Cu in any appreciable concentration illustrates its limits of applicability, but investigations of laser action in numerous new metal vapor systems should be possible.
X-ray measurements of electron temperatures in CO2-laser-heated magnetoplasmas
Authors: Halverson W. , Karmendy C. V.
Published: February 2003

Electron temperatures of CO2-laser-heated magnetoplasmas were found from differential measurements of soft x-ray continuum through gaseous absorbers. We observed in argon and helium-argon plasmas that Te increases with longitudinal magnetic field and is a strongly peaked function of the pressure of the target gas. Plasma dynamics are strongly influenced by the presence of at least eight-times-ionized argon.
Role of integrated lateral stress in surface deformation of He-implanted surfaces
Authors: EerNisse E. P. , Picraux S. T.
Published: February 2003

The first measurements of integrated lateral stress S have been obtained for He implantations to fluences where surface deformation occurs. Implants into Mo, Nb, and Al were carried out at room temperature. The low-fluence results provide values for the induced volume expansion per implanted He atom. The high-fluence results demonstrate that blistering, as observed in Mo and Nb, is directly related to relief of S. However, flaking, as observed in Al, does not result in appreciable relief of S. The saturation value of integrated lateral stress, Smax, is proportional to yield stress for the three materials and is independent of the He projected range. A model to describe the blistering phenomenon is developed based on the standard elastic stability equation for a plate subjected to in-plane forces. This elastic instability model uses only measurable material parameters and does not depend explicitly on the behavior of He in the material. The model explains the τ∝d2/3 relation observed for blister diameter d and thickness τ, and predicts the d-vs-τ relation for Nb, Ti, V, Pd, 4301 SS, and Be to within 40% of the values measured by other workers over 3 orders of magnitude variation in d. Comparison of the model with the present Mo and Nb results, where Smax is measured directly, gives agreement to better than 10% with no adjustable parameter.
Low-frequency noise spectra of a superconducting magnetic gradiometer
Authors: Gillespie George H. , Podney Walter N. , Buxton James L.
Published: February 2003

We present the first measurements of spectra that characterize noise in the frequency range 5×10−4 to 20 Hz of a superconducting magnetic gradiometer operating in a magnetically quiet environment. Spectra are effectively white at frequencies above about 0.1 Hz with a spectral power density of 0.03 (pT/m)2 Hz−1(1 pT/m=10−12 T/m=10−10 G/cm =10−3 γ/m) and are of the form S (f) =S (fo)(fo/f)γ at frequencies below 0.1 Hz. A value of 1.3 for γ with S (fo) =0.002 (pT/m)2 Hz−1 at fo=1Hz is representative of values observed during the quietest observational periods. Intrinsic noise of the superconducting quantum interference device (SQUID) then dominates observed spectra at frequencies below 0.1 Hz.
Experimental techniques for studying the reliability of bubble memory devices
Authors: Chen T. T. , Tocci L. R. , Archer J. L.
Published: February 2003

The reliability of a large capacity bubble memory device was studied by measuring the error accumulation in the stored data resulting from the random annihilation of bubbles during the operation of the device. The bubble-population dependence of the error-rate plot indicates a strong dependence of the device reliability on the bubble pattern. To compare the long-term margin degradation the initial error rate at a fixed bubble population, the inverse of the mean step to failure, is used as the comparison parameter rather than a 50% failure criterion. In this manner, the measurement time required to provide good statistics is greatly reduced when using large capacity chips. In addition, chips of this size are practical ones which can be used in real memory systems. The analysis of the chip reliability is complicated by the many different types of components in the chip and the higher probability of material or processing defects. A generalized field interruption technique is also used to characterize localized areas or components within the large chip. Using this technique in conjunction with the technique of measuring the bubble decay rate at different sites of a repetitive bubble pattern, the direct bubble-bubble interaction in the circuit can be related to the Permalloy geometry. For example, the bent-H-type 180° corner with a diagonal bar was found to cause a significant increase in the error rate in the third bit site of the word pattern 01110111 over that of the pattern 01110000. When the device is operated in start–stop mode, the error rate is further complicated by the static coupling between the bubble and the Permalloy. The effect of bias-field tilting on the device operation reliability can also be studied through a margin degradation-type measurement for the start–stop mode.
Gas phase electrochemistry. II. Adsorption of CH2Cl2 in CF4 on dropping mercury electrode
Authors: Labin R. , Oref I.
Published: February 2003

The specific adsorption of a polar gas on a dropping mercury electrode in the presence of an inert getter is investigated as a function of the pressure in the system and the external applied voltage. The results are compared with an electrocapillary equation which was developed in a previous work. It is found that CF4 is not specifically adsorbed on the mercury surface while CH2Cl2 is, and that the surface concentration of the latter in the presence of the former is independent of the applied voltage in the range ±3 kV.
Characterization of crystal defects at leakage sites in charge-coupled devices
Authors: Ogden R. , Wilkinson J. M.
Published: February 2003

Crystal defects have been identified at the sites of high leakage (spikes) in charge-coupled devices operated in the integration mode. Oxidation-induced stacking faults and dislocations were observed using x-ray topography and selective etching, and identified by transmission electron microscopy. Electrical measurements showed that the stacking faults had a range of activity which is attributed to variation in the level of impurity decoration of the defects.
Wetting of quartz surfaces by Au-Si eutectic melt
Authors: Tu K. N. , Libertini S. H.
Published: February 2003

A wetting experiment with a Au-Si eutectic melt on surfaces of fused and single-crystal quartz has been performed in an atmosphere of He. The wetting shows that the melt reacts with quartz and the wetting angle is about 10°.
The angular variation of the sputter yield peak for silica glass targets
Authors: Witcomb M. J.
Published: February 2003

A relation based on ion reflection at a surface atom plane is shown to be capable of predicting the angular position of the maxima of the sputter yield curve for silica glass targets under bombardment by ions in the energy range 3–50 keV for 19 different ion-ion energy combinations.
Radial profiles of upper- and lower-laser-level emission in an oscillating He-Ne laser
Authors: Ihjima Toshiyuki , Kuroda Kazuo , Ogura Iwao
Published: February 2003

Radial profiles of the emission from upper- and lower-laser-level atoms (Ne 3s2 and 2p4, respectively) have been investigated in a He-Ne laser. The obtained profiles of emission from Ne 3s2-level atoms are appreciably broader than the zero-order Bessel function profile. Change in the radial profiles of population inversion brought about by lasing action have also been investigated and a significant dip in the tube center is observed.
The lensed high-voltage vertical multijunction solar cell
Authors: Soukup R. J.
Published: February 2003

The vertical multijunction solar cell with covering lens is a photovoltaic device which promises high-voltage, high-efficiency outputs. The structure described here is a modification of a structure previously reported. It is shown that the original high-voltage vertical multijunction solar cell is capable of high voltages but not high efficiencies. The solar cell described here is capable of higher efficiencies, but a more detailed analysis than presented here is necessary before a comparison between this cell and a conventional solar cell can be made.
Reply to ’’New analysis of a high-voltage vertical multijunction solar cell’’
Authors: Soukup R. J.
Published: February 2003

An analysis is presented which demonstrates that a vertical multijunction solar cell with covering lens does have optimum dimensions. The analysis does point out that the optimum dimensions would indeed eliminate any dark junctions in series with illuminated junctions for maximum efficiency. Thus, back-to-back p-n junctions should not be designed into a solar cell.
Observation of antiferromagnetic domains in nickel oxide by neutron diffraction topography
Authors: Baruchel J. , Schlenker M. , Roth W. L.
Published: February 2003

The antiferromagnetic T-domain structure of a single-crystal plate of NiO was investigated by neutron diffraction topography. Two modes of observation were used. Topographs made using nuclear reflections provide images of the domain walls because of the change in lattice distortion associated with the antiferromagnetic ordering via exchange striction; the (non)visibility of walls depends on the Bragg reflection used, and is in good agreement with calculations. On topographs made using magnetic reflections, only one type of domain is imaged at a time, yielding unambiguous identification of the magnetic arrangement in each domain.
Zn-ion-implantation profiles in CuInSe2 by Auger electron spectroscopy
Authors: Yu Phil Won , Grant J. T. , Park Y. S. , Haas T. W.
Published: February 2003

The depth distribution of implanted Zn in CuInSe2 was investigated using Auger electron spectroscopy coupled with continuous surface layer removal by argon-ion sputtering. The distribution was found to be influenced by the dose rate used in the implantation. The distribution obtained at a current density of 0.16 μA/cm2 is composed of two parts; one having a nearly Gaussian shape in the leading edge and the other having a nearly exponential shape in the trailing edge after the peak concentration. The tail appears to be due to a rapid diffusion process such as interstitial diffusion. A strong diffusion to the surface was observed from the samples implanted with a current density of 2 μA/cm2. This out-diffusion may occur through the damaged region as it has a lower activation energy.
Origin of the Nonsinusoidal current-phase relation of a superconducting bridge
Authors: Sugahara Masanori
Published: February 2003

The current-phase relation of a long superconducting bridge is investigated with the use of the Aslamazov-Larkin model and the Ginzburg-Landau equation. The feedback effect of the supercurrent to the phase difference in the weak link is taken into consideration. The derived nonsinusoidal current-phase relation explains the experiments of Jackel et al. very well.
Optical properties of cosputtered gold-chromium alloy films
Authors: Slusark W. , Lalevic B. , Ausloos M.
Published: February 2003

Optical properties of cosputtered thin-film (1500 Å) polycrystalline Au-Cr alloys have been investigated in the energy range 0.2–6.1 eV. Cosputtering of Au and Cr has extended the solubility limits of Cr in Au from 20 to 48 at.%. The reflectance data were analyzed by the Kramers-Kronig method and presented in terms of intraband, and interband contributions. The observed frequency dependence of the relaxation time is explained on the basis of a two carrier mode. The shift in the Fermi level with increasing Cr concentration is found to be closer to the prediction of the Friedel theory than the rigid band model. The character of critical points for the interband transitions has been identified.
Two-dimensional time-dependent analysis of the switching of a thyristor
Authors: Hu Shih-Pei , Rabinovici Benjamin M.
Published: February 2003

Two-dimensional time-dependent analysis was carried out for the switching of a thyristor by solving diffusion equations for minority-carrier distributions with realistic boundary conditions and device geometry considered. By using the technique of Laplace transform, the solutions were obtained in closed form and calculated numerically. Two-dimensional current density distributions within an interdigitated thyristor were calculated and plotted for various times during the process of ’’turn-on’’. An optoelectronic system was constructed to map device thermal profile by taking infrared absorption measurements. Correlation between current density distribution calculated and thermal profile measured were investigated and found useful as a justification of this analysis.
Upside-down fabricated GaP monolithic display
Authors: Kitada Masahiro
Published: February 2003

An upside-down fabricated GaP monolithic display having p-n junctions formed by zinc diffusion is developed and the feasibility of practical use studied. In this device, the zinc diffusion is performed at a temperature in the vicinity of 650 °C to increase the efficiency. The device front plane with the p-n-junction segments faces the substrate upon which individual digits are assembled, and the light emitted from the p-n junctions travels through the GaP chip and exits from the polished back plane, which faces the observer. The individual wire bonding of each segment is eliminated using flip-chip technique. It is thought that this device is the most suitable for practical use.
Open-circuit voltage of a Schottky-barrier solar cell
Authors: Dubey P. K. , Paranjape V. V.
Published: February 2003

The open-circuit voltage developed across a Schottky-barrier solar cell is calculated in the presence of monochromatic light. The limitations of previous treatments are brought out. Our analysis differs from the earlier ones in using appropriate boundary conditions. A tractable expression for the open-circuit voltage is obtained assuming low-level injection conditions, which is met by average solar radiation in AM0 and AM1 conditions.
Low-noise and high-power GaAs microwave field-effect transistors prepared by molecular beam epitaxy
Authors: Cho A. Y. , DiLorenzo J. V. , Hewitt B. S. , Niehaus W. C. , Schlosser W. O. , Radice C.
Published: February 2003

The low-noise FET’s prepared on molecular-beam-epitaxial (MBE) layers have a noise figure of 1.9 dB with a corresponding gain of 11 dB at 6 GHz. The power FET’s can produce 1.3 W at 4.4 GHz (1-dB compression) with a gain of 10 dB and a power-added efficiency of 35%. The influence of substrate preparation on Hall mobility for very thin layers was also studied and there is no evidence of Cr diffusion from the substrate at the MBE growth temperature.
Output characteristics of the CuCl double-pulse laser at small pumping pulse delays
Authors: Cem Gokay M. , Jenkins Robert S. , Cross Lee A.
Published: February 2003

An investigation of the two output energies at 5106 and 5782 Å of a CuCl double-pulse laser has shown that the two have different dependences on the delay between pulses. The 5782-Å transition, normally the lower-gain and lower-power one, becomes dominant at small values of the delay time between pulses. This effect is observable at all values of the CuCl vapor pressure but is especially obvious at low CuCl concentration. This differential dependence is attributed to the difference between the relaxation times of the two metastable Cu laser terminal states.
Acoustic emission and stacking-fault energy
Authors: Hatano Hajime
Published: February 2003

A correlation between the acoustic emission accompanying the plastic deformation of face-centered-cubic single crystals and polycrystals and stacking-fault energy is established. The elastic power of acoustic emission has been measured by a quantitative method in a frequency range 100 kHz–4 MHz. In polycrystals it decreases in the order Cu, α-brass, and stainless steel, while in Cu single crystals it is reduced remarkably by addition of Al. The acoustic-emission power diminishes rapidly with decreasing stacking-fault energy in each of the single crystals and polycrystals.
The displacive stability of a void in a void lattice
Authors: Brailsford A. D.
Published: February 2003

It has recently been suggested that the stability of the void-lattice structure in irradiated metals may be attributed to the effect of the overlapping of the point-defect diffusion fields associated with each void. It is shown here, however, that the effect is much too weak. When one void is displaced from its lattice site, the displacement is shown to relax to zero as proposed, but a conservative estimate indicates that the characteristic time is equivalent to an irradiation dose of the order of 300 displacements per atom which is generally much greater than the dose necessary for void-lattice formation.
Argon implantation gettering for a ’’through-oxide’’ arsenic-implanted layer
Authors: Murase Katsumi , Harada Hiroyuki
Published: February 2003

Argon implantation gettering was investigated to improve p-n junctions made by high-dose arsenic implantation through oxide film. Arsenic was implanted into p-type silicon through 520 Å oxide at 2×1015 to 1×1016 cm−2, 100–110 keV. When argon was implanted on the wafer back side at 1×1016 cm−2, 200 keV following arsenic implantation, all junctions showed hard breakdown. However, many junctions without argon implantation showed soft breakdown with large leakage current. Argon implantation reduced etch pits appearing in the arsenic-implanted region.
Growth and characterization of lattice-matched epitaxial films of GaxIn1−xAs/InP by liquid-phase epitaxy
Authors: Pearsall T. P. , Hopson R. W.
Published: February 2003

We determined the conditions for successful lattice-matched growth by liquid-phase epitaxy near T=600 °C of GaxIn1−xAs on 〈111B〉 InP substrates. We have used the results of the growth of both lattice-matched and intentionally lattice-mismatched epitaxial layers (0.4<x<0.7) to produce a calculation of the phase diagram which gives the correct liquidus temperature (TL±1 °C) and the correct solid composition (±5% of the nominal composition) for the entire range of growth solutions considered for this important ternary semiconductor system. The parameters appropriate to this calculation are significantly different from those used to describe the growth of GaxIn1−xAs on GaAs. The results of this calculation play an important part in the better understanding of the quaternary alloy GaxIn1—xAsyP1−y.
Threshold switching in polycrystalline TiO2 thin films
Authors: Taylor G. , Lalevic B.
Published: February 2003

I-V characteristics, Balberg’s double-pulse test, and rf relaxation oscillation were used to analyze the switching mechanism in Ti-TiO2-Cr devices. Experimental results show an overall agreement with Lampert’s double-injection model; however, alternate electronic mechanisms should not be ruled out.
The shocked piezoelectric disk as a Maxwell solid
Authors: Duvall George E.
Published: February 2003

When a shock wave passes through a piezoelectric disk with electrodes on front and back faces, a current can be made to pass through an external circuit connecting the electrodes. Pressure in the shock wave can be related to stress and current through a Maxwell-like relation in which the stress-relaxation function is proportional to the current. External current is shown to be related to other parameters of the problem through an integral equation for its Laplace transform.
A spectroscopic study on the evaporation of aluminum as irradiated by a long-pulse Nd laser
Authors: Wei P. S. P.
Published: February 2003

The plasma plume produced by a focused Nd laser beam (1.06 μm, 43 J, 1.2 msec) on an aluminum plate in air at power densities up to 3×107 W/cm2 has been studied by the spectroscopic technique. The average speed of the luminous vapor jet is measured to be 8×103 cm/sec by the time-of-flight method. The emission spectrum, which consists mainly of Al and AlO, is similar to that from an electric arc. The temperature of the plasma is estimated to be ?1 eV fom a theoretical analysis of the equilibrium composition of the A1-O system in the gas phase. Of particular interest is the detection of optically forbidden transitions from the np (2P) and nf (2F) states to the 3p (2P) ground state of AlI due to the instantaneously high density and electric field. From the Stark shift of the self-reversed 4d lines, the ion density is estimated as 9×1017/cm3. These results suggest that laser evaporation may be a novel source for studying atomic and molecular spectra at high density.
Color in "tungsten trioxide" thin films
Authors: Gerard P. , Deneuville A. , Hollinger G. , Duc Tran Minh
Published: February 2003

We show that evaporated tungsten trioxide amorphous layers commonly used in electrochromic displays actually have the composition WO2.7Hy (0.2<y<0.5). We emphasize that coloration of virgin transparent films can be obtained without injection of any external ion into the layer, and further that around a critical substoichiometry by sputtering, namely, WO2.5, one can prepare blue virgin layers without any hydrogen. The effect of substoichiometry on the valence of tungsten atoms has been followed by XPS measurements of sputtered layers.
Investigation of the microwave magnetoplasma matching effect in indium antimonide
Authors: Brazis R. S. , Furdyna J. K.
Published: February 2003

Reflection and transmission of microwaves normally incident on a magnetized semiconductor plasma are investigated in the presence of a dielectric quarter-wave layer. Faraday geometry is specifically considered, although conclusions of this work can be generalized to other geometries. Experiments are performed on n-type InSb at 35 GHz between 80 and 300 K. Four characteristic effects caused by the presence of the quarter-wave plate are reported. The first of these, referred to as the ’’magnetoplasma matching effect’’, is the nonresonant minimum of reflectivity observed when the applied dc magnetic field is varied. This effect is shown to be observable over a broad range of values of the effective dielectric constant κeff (including extremely large values, e.g., the helicon wave regime), as long as κeff≳0. Observation of this effect provides a direct measure of κeff, independent of particular microscopic models of this function. The second effect is the enhancement of reflected phase shift. The phase as a function of dc magnetic field is found to have a well-defined minimum between cyclotron resonance and magnetoplasma matching conditions. This effect provides a new tool for investigation of electronic parameters in narrow-gap semiconductors. The enhanced phase change is observed even in the evanescent wave regime (κeff<0) —an especially important feature, since the region of evanescence is notoriously inaccessible to measurements. Third, a great enhancement of the power absorbed by the semiconductor half-space is shown to occur over a broad range of parameters. This is important when κeff is very large, so that half-space absorptivity (without the quarter-wave plate) is too small to be measured accurately. Fourth, extremely large enhancement of transmission through a slab (by several orders of magnitude) is observed over a wide range of dc magnetic fields. Finally, limitations of magnetoplasma matching caused by high-order mode generation are discussed.
Dependence of the Si-SiO2 barrier height on SiO2 thickness in MOS tunnel structures
Authors: Kasprzak L. A. , Laibowitz R. B. , Ohring M.
Published: February 2003

Ultrathin (10–30 Å) SiO2 layers with large interface-state densities were used as the dielectric between aluminum and degenerate silicon. The presence of interface states resulted in current-vs-voltage curves characteristic of metal-insulator-metal (MIM) tunnel structures. MIM tunneling theory was used to estimate the Si-SiO2 (φSi-SiO2) and the Al-SiO2 (φAl-SiO2) barrier heights. We found that the Si-SiO2 barrier height increased from 0.42 eV at 10 Å to 0.65 eV for 25.5 Å of SiO2 on degenerate p-type Si, and from 0.64 eV at 14 Å to 1.27 eV for 29.3 Å of SiO2 on degenerate n-type Si. The Al-SiO2 barrier height could not be consistently determined but was about 0.61±0.16 eV. A smooth transition from Schottky barrier to MOS tunnel structure was observed. The thickness dependence of φSi-SiO2 is most likely due to the recently observed 15–20-Å nonstoichiometric SiO transition region at the Si-SiO2 interface.
Photoemission studies of the cesiation of ZnO
Authors: Powell R. A. , Spicer W. E.
Published: February 2003

We report the first ultraviolet photoemission spectroscopy (UPS) measurements for (Cs)ZnO. Our data confirm the results of Sommer and Briere that successful cesiation of sprayed ZnO powders can be achieved. ZnO is, to our knowledge, the first II-VI semiconductor for which this has been reported, although cesiation of III-V compounds (e.g., GaAs and InP) has been performed for many years. A saturation exposure to Cs at 8×10−8 Torr (corresponding to 25 L Cs) dramatically lowers the work function to approximately 1.3 eV. The sticking coefficient of Cs on ZnO is estimated at ?0.2. Of particular technical importance is the ease of preparing extremely clean ZnO surfaces, viz., simple annealing in vacuum to ?500 °C results in samples whose UPS spectra are nearly identical to those from in situ cleaved (101̄0) ZnO. Strong thermal desorption of Cs was observed when (Cs)ZnO was annealed at 600 °C in UHV.
Fusion-neutron-induced nuclear recoil emission probabilities
Authors: Harling O. K. , Thomas M. T. , Brodzinski R. L. , Rancitelli L. A.
Published: February 2003

High-energy neutrons such as those from the (d,t) reaction are capable of producing radioactive recoil particles which can be ejected from the surfaces of irradiated materials. We have made extensive measurements of such recoil emission probabilities with 14.8-MeV (d,t) neutrons and some measurements with a 40-MeV (d,Be) neutrons source. Recoil emission ratios are reported for targets of Nb, Mo, V, 316 SS, Fe, Ni, Cr, Ti, and Au which include 23 different fast-neutron-induced reactions. The total radioactive recoil sputtering ratio for each target range in magnitude from 3×10−8 to 3×10−7 recoil atoms/neutron for forward sputtering. Effective recoil atom ranges have been obtained from the experimental data and these are compared with theoretically calculated ranges. Various metallurgical preparations were used for the targets. Some implications of this radioactive recoil sputtering, regular neutron sputtering, and chemical corrosion to future controlled fusion machines are discussed. Neutron ejection of radioactive wall atoms is identified as being of potentially major significance in the operation and maintenance of future fusion reactors.
Projected range calculations of radionuclide product ejection from metal surfaces by 14.8-MeV neutrons
Authors: Lessor D. L. , Thomas M. T. , Harling O. K.
Published: February 2003

A calculation has been made of the radionuclide product ejection from several elemental metal foils and a stain-steel alloy foil from (n,x) reactions in a normally incident 14.8-MeV neutron flux and compared with experimental data. The recoiling heavy products from the (n,x) reactions were assumed to propagate on the average in straight lines with a definite range-vs-energy relationship. With this assumption, for each distance x from the surface, an angle ϑcmc is found such that product nuclei at center-of-mass angles ϑcm<ϑcmc leave the material while those at angle ϑcm≳ϑcmc on the average come to rest in the material medium. Calculated sputtering rates range from slightly below to a factor of 2 above experimental values. This agreement is judged to be good considering the assumptions of the model, the assumptions used to generate the range tables, and the uncertainties in the experimentally determined sputtering rates.
Relativistic yield spectra for H2
Authors: Garvey R. H. , Porter H. S. , Green A. E. S.
Published: February 2003

We present a complete set of relativistic electron-impact cross sections for H2. Using these cross sections we calculate the yield spectrum, which is related to the degradation spectrum, using a modified form of the discrete-energy-bin (DEB) method of energy apportionment. In an appendix, we describe those modifications to the DEB approach which make its use practical in high-energy calculations. We point out the relatively simple form the yield spectrum has and we present an accurate fit to the yield spectra using a seven-parameter function. Lastly, we show that the observed dependences of both the yield spectra and ionization probability on energy lead to the approximate independence of the energy per ion pair as a function of incident energy at high energies.
Visualization of polymer interfaces by phase contrast (’’defocus’’) electron microscopy
Authors: Christner G. L. , Thomas E. L.
Published: February 2003

A significant problem in studies of polymer microstructure is obtaining enough contrast in electron micrographs to visualize the system. Most techniques now used take advantage of amplitude changes produced by the interaction of the electron beam with the object. In this paper we investigate the possibility of using phase changes induced in the electrons by the object and by microscope defocus to produce usable image contrast. We use the standard linear transfer theory of microscope imaging to evaluate the images produced by several different model objects. The basic structure investigated is an alternating sequence of domains. These models correspond reasonably closely to the suggested microstructure of several polymer systems and the calculations should be directly applicable to them. Our calculations show that for reasonable inner potential changes and film thickness usable image contrast can be obtained. The technique is most sensitive to rapid phase changes and will be most successful with objects having sharp rather than diffuse domain boundaries. Defocusing produces fringes at the domain boundaries with the size of these fringes depending on both the object and the amount of defocus. The results indicate that defocusing is useful for polymer structure investigations. However, the defocused image will not correspond directly to the object structure, and some care must be taken in deducing the true object structure.