bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of krypton on CrSi2 formation
Authors: Zheng L. R. , Hung L. S. , Chen S. H. , Mayer J. W.
Published: July 2002

The influence and redistribution of the inert gas Kr in chromium silicide formation have been investigated by MeV He backscattering spectrometry and transmission electron microscopy. It was found that krypton implanted in the chromium film remains stationary with respect to the chromium during silicide formation, but krypton implanted in the silicon substrate accumulate at the silicon/silicide interface. The effect of krypton on the rate of silicide formation is much more pronounced when the krypton is in the chromium rather than in the silicon substrate. The thermal growth of CrSi2 is linear with time in a krypton-free sample, but becomes parabolic when the krypton is incorporated in the silicide at a concentration of 1 at. %. The activation energy associated with Si diffusion through CrSi2 is increased from 1.4±0.1 eV to 2.6±0.1 eV by the presence of krypton in the silicide. The results are interpreted as being due to segregation of krypton on grain boundaries in CrSi2 and subsequent retardation of diffusion along the boundaries.
Absolute photoionization cross sections of the acceptor state level of chromium in indium phosphide
Authors: Bremond G. , Guillot G. , Nouailhat A. , Picoli G.
Published: July 2002

We have studied by deep-level transient spectroscopy and deep-level optical spectroscopy n-type chromium-doped InP. We definitively confirm that the Cr2+/Cr3+ acceptor state is positioned at EC −0.4 eV in InP. We have measured for the first time the absolute values of the photoionization cross sections of Cr2+ in InP by deep-level optical spectroscopy. The σ0n cross section exhibits both a resonant and a nonresonant character. The former corresponds to the internal transition 5T2→5E of Cr2+, while the latter is attributed to the photoexcitation from the Cr2+ to the conduction band. The threshold of this transition at EC −0.41 eV indicates a very small Franck–Condon shift. The scales of the absolute photoionization values (σ0n) and photoneutralization (σ0p) cross sections towards the conduction and valence bands are the same, which seems to indicate no selection rules.
Turn-off characteristics of bistable laser diode
Authors: Tomita Akihisa , Terakado Tomoji , Suzuki Akira
Published: July 2002

Turn-off characteristics for tandem-electrode bistable laser diodes (bistable LD’s) were analyzed both experimentally and theoretically. A long tail in the light output waveform was observed when the turn-off injection current was near the switch-down current. Rate equations were solved with adiabatic approximation and gave a good explanation indicating that the tail was due to the relatively slow recovery of the saturable absorber. The analysis also showed that the turn-off time for bistable LD’s can be reduced to that for ordinary laser diodes, with sufficiently small injection current. Subnanosecond operation for bistable LD’s was found possible under optimal turn-off injection current.
Flexural resonance measurements of clamped and partially clamped disks excited by nanosecond laser pulses
Authors: Crosbie R. A. , Dewhurst R. J. , Palmer S. B.
Published: July 2002

Nanosecond pulses from a Nd:YAG laser are used to excite clamped aluminum disks to resonance. The first two flexural vibration modes are shown to be in agreement with classical plate theory. This theory is then applied to the case of flat-bottomed holes in aluminum plates, when the remainder of the plate below the hole may be said to be partially clamped. It is shown that the theory can still be used over a well-defined regime. In addition, the depth of the hole can be obtained from the ring-around longitudinal ultrasonic pulse generated by the laser. A combination of these two techniques, therefore, allows a sizing of circularlike flaws in laminations lying close to a sample’s surface.
Optical beam frequency modulation by using surface-acoustic-wave delay line oscillator
Authors: Toda Kohji , Watabe Kohji
Published: July 2002

A frequency-modulation technique for an optical beam is described, which uses a surface-acoustic-wave delay line oscillator. The surface wave propagating on a piezoelectric substrate is mode converted to a longitudinal wave at one end of the substrate plate immersed in water. The sound wave operates as a grating for an optical beam. The use of this type of grating for the frequency modulation is demonstrated for a combination of a He–Ne 0.6328-μm laser and a 2.8-MHz surface-wave device.
Study of electrical breakdown induced by pulsed CO2 laser radiation
Authors: Yoshida S. , Kubodera S. , Sakai T. , Ozaki R. , Uchiyama T.
Published: July 2002

Electrical breakdown streamers have been triggered in atmospheric air by laser-induced ionization. Streamers were successfully triggered even when the voltage applied to the electrodes was too low for breakdown to occur by the influence of the electrical field alone. The lifetime of the observed triggering effect has been found to be no less than 1 ms. Laser-induced streamers were photographically studied and conveniently classified by their observed shapes. In addition, the statistics of the observed phenomena have been compiled according to the classified shape. The statistics indicate that the shape of streamer is likely to be determined by the degree of laser-induced ionization. It has also been found that the speed of streamer formation is strongly related to the degree of ionization.
Chemical-reaction and diffusion rates in solids produced by shock compression
Authors: Kleiman J. , Chan P. W. C. , Salansky N. , Glass I. I.
Published: July 2002

Explosive-driven hemispherical-implosions were used to create high dynamic pressures (up to 13 GPa) and temperatures (up to 450 K) in an exploratory investigation of chemical reactions and diffusion processes in different materials subjected to extreme conditions. Diffusion coefficients as high as 200 cm2/s and chemical reaction rates as fast as 1000 mol/s (in a volume of 0.2 cm3) were inferred from shock experiments with carbontetrabromide (CBr4) and copper (Cu) powder mixtures. An outdiffusion of Ga from a single crystal GaAs substrate into a polycrystalline indium thin film deposited on it was also observed and confirmed by scanning electron microscopy and energy dispersive x-ray microanalysis.
The air mass zero behavior of inversion layer solar cells with a silicon nitride dielectric layer
Authors: Burte Edmund P.
Published: July 2002

The reliability of metal-insulator-semiconductor (MIS) inversion layer (IL) solar cells with a plasma-deposited silicon-nitride dielectric layer is investigated by irradiating these cells with a mercury super pressure lamp. In comparison to the air mass zero (AM0) sun spectrum this is a slightly accelerated testing procedure. The dependence of the dark and illuminated I-V characteristics of the cells on the irradiation time is monitored. As revealed by the experiments, the values of the short-circuit current, of the open-circuit voltage, and of the fill factor of these cells diminish by irradiation. As a consequence, a drastic decrease of the air mass one (AM1) total-area efficiency can be observed. The observed irradiation effects can be understood by introducing an inversion layer recombination current which is due to photon-generated interface states at the silicon nitride/thin silicon oxide/silicon interface.
Contact resistance measurements for hydrogenated amorphous silicon solar cell structures
Authors: Schade H. , Smith Z E.
Published: July 2002

A technique for measuring the electrical characteristics of contacts to doped hydrogenated amorphous silicon (a-Si:H) or other high-resistivity thin-film semiconductors is developed. Experimental results for metal and conductive transparent oxide contacts to both n- and p-type a-Si:H are presented and the significance of these values to solar cell applications discussed.
Fabrication technology for lead-alloy Josephson devices for high-density integrated circuits
Authors: Imamura T. , Hoko H. , Tamura H. , Yoshida A. , Suzuki H. , Morohashi S. , Ohara S. , Hasuo S. , Yamaoka T.
Published: July 2002

Fabrication technology for lead-alloy Josephson devices was evaluated from the viewpoint of application to large-scale integrated circuits. Metal and insulating layers used in the circuits were evaluated, and optimization of techniques for deposition or formation of these layers was investigated. Metallization of the Pb-In-Au base electrode and the Pb-Bi counterelectrode was studied in terms of optimizing the deposited films, to improve the reliability of junction electrodes. The formation of the oxide barrier was studied by in situ ellipsometry. SiOx deposited in oxygen was developed as the insulation layer with less defect density than conventional SiO. A liftoff technique using toluene soaking was developed, and patterns with a minimum line width of 2 μm were consistently reproduced. The characteristics of each element in the circuits were evaluated for test vehicles. For the junction, the following items were evaluated: controllability of the critical current Ic, junction quality, Ic uniformity, junction yield, and thermal cycling and storage stability. For the peripheral elements, integrity of lines and contacts, and characteristics of resistors were evaluated. 8-kbit memory cell arrays with a full vertical structure were fabricated to evaluate these technologies in combination. The continuity of each metal layer and insulation between metal layers were evaluated with an autoprober at room temperature. For selected chips, cell characteristics have been measured, and their Ic uniformity and production yields for cells are discussed. Normal operation of the memory cells was confirmed for all of the 24 accessible cells on a chip. Finally, we discuss the feasibility of Josephson large-scale integrated circuits using lead-alloy materials.
Fundamental relativistic solution for the rail gun
Authors: Liboff Richard L. , Schenter Gregory K.
Published: July 2002

A fully relativistic analysis is made of the dynamics of a rail gun based on three assumptions: (1) Ohm’s law is valid in the rest frame of the plasma, (2) total electron momentum is transferred to the projectile, and (3) motion of the projectile is constrained to one direction. With these assumptions, a relativistic equation for the velocity of the projectile is obtained, whose solution monotonically increases to one of two values depending on field strengths. For B>E, the maximum velocity is cE/B, whereas for E>B it is c, where c is the speed of light, and E and B are applied electric and magnetic fields, respectively (in cgs).
Indium doping effects on vapor-phase growth of ZnS on GaP
Authors: Fuke S. , Araki H. , Kuwahara K. , Imai T.
Published: July 2002

Single-crystal layers of ZnS have been grown on GaP substrates in a hydrogen transport system. By the addition of In to the reactant agents, the orientation dependence of the growth rates of ZnS are reversed for (111)A and (111)B substrates. The improvement of crystallinity of the grown layers can be seen by the surface morphology observation and x-ray and reflection high-energy electron diffraction analyses. These phenomena are undoubtedly caused by the In-incorporation effects during the epitaxial growth of ZnS.
Transport properties of high purity, polycrystalline titanium diboride
Authors: Williams R. K. , Graves R. S. , Weaver F. J.
Published: July 2002

Thermal conductivity data for several TiB2 samples are presented and the results for one sample extend from 80 to 400 K. These results show that the thermal conductivity attains a maximum value of about 130 W/m K at 140 K. An analysis of the results shows that this is caused by the electronic component of the thermal conductivity and that phonon conduction is also probably significant. Seebeck coefficient values agreed with the results of previous studies. The electrical resistivity of one sample was also determined to 1800 K. These results can be described by the Bloch–Grüneisen equation if the effect of thermal expansion is included.
Hole transport behavior of N-phenylcarbazole-doped poly(bisphenol A carbonate) films in a glass transition region
Authors: Tsutsumi Naoto , Yamamoto Masahide , Nishijima Yasunori
Published: July 2002

Hole mobility of a N-phenylcarbazole-doped poly(bisphenol A carbonate) system was measured by the time-of-flight method at −60 to 130 °C, which covers the glass transition temperature Tg of the poly(bisphenol A carbonate) matrix. The hole mobility at T=298 K and E=1.6×105 V cm−1 changes from 1.7×10−8 to 6.6×10−6 cm2 V−1 s−1 with the increase of N-phenylcarbazole concentration from 7.5×10−4 to 2.4×10−3 mol cm−3. Above Tg, the activation energy of hole mobility is smaller than that below Tg. This implies that the micro-Brownian motion of polymer chain in the glass transition region changes the trap level for hole transport, i.e., the trap level becomes shallower in the temperature range above Tg. The shape of the transient photocurrent was also studied at various temperatures. The value of (t1/2−tT) is used as an indicator of the trapping effect, where tT is the transit time and t1/2 is the time when the transient photocurrent becomes half of the photocurrent at tT. The slope of the plot of (t1/2−tT) vs T was found to change discontinuously in the glass transition region. This result also supports the change of the trap level in the glass transition region.
Luminescence of heavily electron irradiated InP
Authors: Frandon J. , Fabre F. , Bacquet G. , Bandet J. , Reynaud F.
Published: July 2002

InP n-type single crystals are electron irradiated using very high fluences at various temperatures. Their photoluminescence is investigated at 1.7 K. No strong quenching of ‘‘intrinsic’’ luminescence is noticed after this treatment. Five extra emission lines are observed in the near-band-gap energy range, with samples irradiated in convenient temperature conditions. One of these lines (at 1.392 eV) is related to electron irradiation. The other emissions may be also observed on crystals only annealed under vacuum. The excitonlike line found at 1.398 eV is shown to be correlated with the 1.08 eV band involving a deep secondary defect. A tentative assignment is proposed for these emissions.
A new analysis of the linear high-field magnetoresistance in n-type PbTe films
Authors: Allgaier R. S.
Published: July 2002

This note reexamines the importance of geometrical effects on the high-field linear magnetoresistance (MR) which has been observed in epitaxial films of n-type PbTe. It concludes that most of the MR, when it becomes large, is due to the end-shorting effect first analyzed by Wick. A simple derivation of Wick’s result is presented for the limiting case when the Hall angle approaches 90°. The new interpretation implies that end effects spread further along the sample length than the idealized theory predicts. This may also be relevant to the quantum Hall-effect regime, where deviations from precisely quantized values have been observed with increasing sample temperature.
Relaxation of optically induced inversion layers in metal-insulator-semiconductor tunnel diodes
Authors: Dahlke Walter E. , Jain Sanjay
Published: July 2002

Transient capacity measurements between 77 and 300 K were performed to study the relaxation of optically induced inversion layers in metal-insulator-n silicon structures with 23–176-Å oxide thickness. The observed fluence of the charge in interface and inversion layer exhibits as a function of time three distinct maxima. A theoretical study of the two governing nonlinear differential equations—Shockley–Read–Hall recombination in interface traps, and continuity equation for holes in the valence band—shows that the first peak is caused by recombination in silicon-bulk traps while the second and third peaks are generated by tunneling recombination in interface traps. A quantitative analysis of the data shows satisfactory agreement between experiment and theory.
Photoluminescence from heavily doped Si layers grown by liquid-phase epitaxy
Authors: Wagner J. , Appel W. , Warth M.
Published: July 2002

Heavily phosphorus or gallium-doped silicon was grown by liquid-phase epitaxy and studied by photoluminescence. For the phosphorus-doped samples grown from In(P) solution, recombination of free electrons to compensating In acceptor levels was observed besides the free electron-free hole band-to-band emission. The gallium-doped samples showed a luminescence spectrum similar to the one observed in bulk-doped p-type material, indicating a good crystalline quality and low compensation in these samples. The band-gap shrinkage was found to be larger in heavily gallium-doped than in boron-doped silicon, indicating a dependence of this shrinkage on the chemical nature of the dopant atoms.
Optical absorption of copper colloids in photochromic glasses
Authors: Ruppin R.
Published: July 2002

Calculated optical absorption spectra of colloidal copper particles in photochromic glasses containing both copper halides and cadmium halides are presented. Comparison with available experimental data supports the previously suggested colloidal darkening mechanism. The dielectric constant of the copper particles is obtained from the bulk one by applying either the mean-free-path correction or the quantum size effect correction. It is shown that, using the available experimental data, no conclusion about the superiority of either correction can be drawn.
Neodymium complexes in GaP separated by photoluminescence excitation spectroscopy
Authors: Wagner J. , Ennen H. , Müller H. D.
Published: July 2002

Implantation of neodymium (Nd) in GaP gives rise to a very complex spectrum of intra 4f-shell luminescence transitions involving a number of Nd defect associates. Using a tunable color center laser, photoluminescence excitation spectroscopy was employed to separate different Nd3+ complexes in GaP:Nd. Two dominant noncubic Nd centers are clearly identified which arise presumably from the association of Nd with radiation damage centers.
Photodeposition of GeO2-SiO2 glass and application to planar optical waveguides
Authors: Tate A. , Jinguji K. , Yamada T. , Takato N.
Published: July 2002

First reports on the characteristics and applications of GeO2-SiO2 glass films formed by laser-induced chemical vapor deposition (CVD) are presented. At a low temperature (200–300 °C), solid solutions of ternary compounds can be obtained by laser-induced CVD. It is shown that these GeO2-SiO2 ternary films were applicable to planar optical waveguides.
Analysis of the short-circuit current of a polycrystalline solar cell with excitation by a gated electron beam
Authors: Romanowski A. , Wittry D. B. , Tsaur J. M.
Published: July 2002

A relation for the short-circuit current near a grain boundary perpendicular to the surface of the solar cell is given. In the analysis a point-generation source is assumed. The grain parameters such as the lifetime and the diffusivity of the minority carriers and the effective recombination velocity are determined from the decay curve of the short-circuit current induced by the electron beam. Since the depletion layer capacitance C and the series resistance R in the solar cell are large, the parameter RC is taken into account in the analysis of the short-circuit current.
Internal strain energy in quaternary III-V compound alloys
Authors: Sonomura H.
Published: July 2002

Internal strain energies for quaternary III-V compound alloys of the type AxB1−xCyD1−y have been estimated. The strain is attributable to the difference in bond length among the constituent compounds. Results are shown in the form of contour of the energy. The energies in AlGaAsP are relatively small; the maximum value is about 4 kJ/mol, and those in AlInPSb are large; the maximum is about 50 kJ/mol. The alloys are concluded to be hardly miscible by ordinary growth methods in the domain of strain energies larger than 19 kJ/mol. The qualities of the alloys can be predicted by the internal strain-energy charts presented in this study. The effect of movement of atoms from the virtual crystal-lattice sites is discussed. Comparison to the enthalpy of mixing is also made.
Stimulated emission spectra of AlxGa1−xAs near the direct-indirect gap crossover composition
Authors: Sarfaty R. , Ron Arza , Cohen E. , Logan R. A.
Published: July 2002

The stimulated emission spectra of photoexcited AlxGa1−xAs, 0.42≤x≤0.46 (near the direct-indirect gap crossover xc =0.435) were measured at low temperatures as a function of the illuminated stripe length and excitation intensity. Based on these data, the gain spectra and gain saturation behavior were obtained. The observed gain spectra are explained by calculating the radiative recombination of an electron-hole plasma of constant density with fair agreement between theory and experiment. It is found that above xc the gain spectrum is due to electrons in the indirect-gap minima (X) whose wave function is strongly admixed with the (Γ) minimum by alloy disorder. The saturation of the stimulated emission at higher excitation intensity and at larger stripe length could be explained qualitatively for the direct-gap samples by a model based on electron and hole relaxation within their respective Fermi seas. This model yields the stimulated emission shift towards lower energy with increased excitation intensity or stripe length. The behavior of the indirect-gap samples is different: both ends of the gain spectrum saturate. This behavior cannot be explained by the proposed model.
Evaluation of a defect capture cross section for minority carriers: Application to GaAs
Authors: Stievenard D. , Bourgoin J. C.
Published: July 2002

The majority-carrier trapping cross section for a majority-carrier trap can be obtained using capacitance spectroscopy by monitoring the kinetics of trap filling. This method cannot be applied for the determination of the trapping cross section of minority carrier by this majority-carrier trap because the capture or emission kinetics cannot be observed. Here we propose a method to measure the minority-carrier trapping cross section for majority-carrier trap. It is not a general method but limited to defects which have the property to anneal under minority-carrier injection, a rather common feature in III-V and II-VI semiconductor compounds. For such defects, the annealing rate induced by injection is proportional to the rate of minority carrier trapping. As a result, the study of the annealing rate versus the density of injection and versus the temperature allows us to obtain the minority-carrier trapping cross section and its variation with temperature. The method is illustrated by a study of the so-called E3 defects, created by electron irradiation at room temperature in n-type GaAs. For this defect, we find a minority-carrier cross section which is thermally activated with an activation energy of ∼0.35 eV, implying that the capture of minority carriers, like the capture of majority carriers, occurs through multiphonon emission. A discussion of this result in terms of configuration coordinate diagram shows the limitation of this model.
Theoretical values of various parameters in the Gummel–Poon model of a bipolar junction transistor
Authors: Benumof Reuben , Zoutendyk John
Published: July 2002

Various parameters in the Gummel–Poon model of a bipolar junction transistor are expressed in terms of the basic structure of a transistor. A consistent theoretical approach is used which facilitates an understanding of the foundations and limitations of the derived formulas. The results enable one to predict how changes in the geometry and composition of a transistor would affect performance.
The effects of association and dissociation processes on the anelastic behavior of solute-point defect complexes
Authors: Brailsford A. D.
Published: July 2002

The standard discrete atomic jump model of the relaxation of point defect-solute pairs is augmented by a dynamic continuum model reflecting the effect of the surroundings of the complex. Effective-medium theory is used to derive the response characteristics of this continuum. In this way the effect of dissociation and association of solute-defect pairs on the anelastic behavior of a solid is described quantitatively. The model leads to the prediction of an additional very low-frequency internal friction peak when experiments are carried out at fixed temperature. The relaxation is identified with the ‘‘reaction mode’’ discussed earlier by Nowick. It is investigated in some detail for doped oxide materials. However, the emphasis here is directed less towards extensive comparison with experiment than towards an exposition of the new methodology. For this reason only nearest-neighbor binding between defect and solute is considered and only the trigonal pair in cubic materials is analyzed. However, the generalizations that are necessary in order to remove these restrictions are described.
X-ray double-crystal characterization of highly perfect InGaAs/InP grown by vapor-phase epitaxy
Authors: Macrander A. T. , Strege K. E.
Published: July 2002

Rocking curves of a 0.78-μm layer grown on a 3.35° off-(100) substrate by the hydride process have been compared to detailed calculations using x-ray dynamical diffraction theory. The observed linewidth and peak convoluted reflecting power of the (400) reflection are 32 arc s and 12.4% as compared to calculated values of 26.6 arc s and 17.4%. We used a symmetric (100) InP first crystal, and the calculations were made for this exact geometry. Anomalous dispersion was not neglected. We report the observation of Bragg geometry Pendellosung fringes for this InGaAs layer. As many as six fringes having a separation of 26 arc s were found to be clearly visible. This spacing was fit to obtain the layer thickness. We conclude that, so far as we are aware, our material is the best, as judged from an x-ray point of view, ever reported for the vapor-phase epitaxy process.
Evaluation of the performance of superconducting nonequilibrium devices
Authors: Iguchi Ienari
Published: July 2002

The performance of a superconducting three-terminal nonequilibrium device utilizing quasiparticle-injection phenomena is investigated. The switching time is derived from the transient solution of the rate equations, whereas the gains are calculated from the steady-state solution. For Nb and Pb, the switching times are estimated to be order of 10 ps for sufficiently thin films provided that only the first-half rapid rise part of the transient behavior is used. The gains are weakly dependent on film thickness because of a high phonon trapping factor. For an appropriate magnitude of load resistance, the current and power gains are calculated to be ∼30 and ∼0.5, respectively. These values are considerably increased by taking the double-junction-acceptor geometry.
Stochasticity of particle orbits in a collective particle accelerator
Authors: Ganguli G. , Mitchell H. G. , Palmadesso P.
Published: July 2002

A detailed investigation of the behavior of particle orbits in the simultaneous presence of three large amplitude waves such as those encountered in the collective particle accelerator experiment at the Naval Research Laboratory is undertaken. Stochasticity arising out of the resonance overlap of the waves can influence the particle dynamics significantly and thereby affect the outcome of the experimental results. Choice of initial phase and energy for successful operation is identified and discussed.
Liquidus measurements of Ga-Sb and In-As in the 375–650 °C range
Authors: DeWinter J. C. , Pollack M. A.
Published: July 2002

Measurements of group III-rich Ga-Sb and In-As liquidus compositions in the 375–650 °C range are reported. The data are described well by the simple solution model using interaction parameters varying linearly with temperature.
Light-induced degradation and thermal recovery of the photoconductivity in hydrogenated amorphous silicon films
Authors: Eser E.
Published: July 2002

Kinetics of light-induced degradation and thermal recovery of the photoconductivity in hydrogenated amorphous silicon have been investigated. Rate equations for these processes were derived using the principles of reaction rate theory. Both degradation and recovery were found to be thermally activated with activation energies of 0.1 and 1.35 eV, respectively. Experimental results support the bond breaking model for the degradation. Stabilization of broken bonds is achieved by structural relaxation. Thermal recovery proceeds through hydrogen hopping from one dangling bond to another. Experimental evidence suggests the existence of an upper limit in the density of light-induced defects. A microscopic model, consistent with experimental observations, is proposed for the light-induced generation and thermal recovery of defects in a-Si:H.
Bulk modulus-volume relationship for some crystals with a rock salt structure
Authors: Sirdeshmukh D. B. , Subhadra K. G.
Published: July 2002

Anderson and Nafe [J. Geophys. Res. 70, 3951 (1965)] pointed out that while log K-log V plots for a large number of crystals have a slope of −1, the plot for oxide compounds has a slope of −4. Recent data on the bulk modulus of eight oxides with a NaCl structure are examined. It is observed that the log K-log V plot for these crystals has a slope of −1 and not −4. From this plot it is estimated that these oxides have an effective ionic charge of about 0.8. The data on lead chalcogenides are also examined. It is shown that from the two widely different values of the bulk modulus of PbSe, the physically acceptable value can be sifted out from the log K-log V plot.
Hugoniot measurements for vanadium
Authors: Gathers G. Roger
Published: July 2002

The Hugoniot of vanadium has been measured by means of a two-stage light-gas gun which launches planar impactors at velocities up to 8 km/s. The data fit the relation Us =C+S Up, where Us is shock velocity, Up is particle velocity, C=5.044 km/s, and S=1.242 in the pressure range 20–337 GPa.
Double-injection-induced conductivity between n and p contacts to semi-insulating GaAs
Authors: Flesner L. D. , Nedoluha A. K. , Zuleeg R. , Penchina Claude M.
Published: July 2002

Conductance between ion-implanted, coplanar n and p contacts on nominally undoped semi-insulating (SI) GaAs has been studied. The data reveal a time-dependent double-injection-induced conductance in the SI region between the contacts and an exponential current versus voltage junction conductance. To interpret the data a two-dimensional model is proposed in which current flows in a thin p-like layer near the surface, the conductance of which is modulated by transverse charge separation and consequent electron trapping.
Electrochemical photoconductive technique for measuring the distribution of traps in semi-insulating GaAs
Authors: Sears W. M.
Published: July 2002

In this paper an electrochemical photoconductive technique is introduced as a means of examining the distribution of traps in semi-insulating gallium arsenide (107 Ω cm). This technique involves the use of an electrochemical solution in place of one of the metallic (ohmic) contacts which are used in solid-state photoconduction. Separation of electron and hole traps is possible using an electrochemical solution as a distinction can then be made between conduction- and valence-band current flow. This is accomplished by the use of specific chemical species in solution and the appropriate biasing which then allows only interaction with one band. The current is measured under the application of monochromatic sub-band-gap light as it is scanned from midgap to band-edge energies. This gives the accumulated trap density as successive traps are affected. The samples are illuminated from the back of the crystal to avoid absorption by the solution and to allow uniform illumination of all contacts (on the front). From the photoconductive scans (anodic, cathodic, and solid state) and the bias (I-V) dependence the magnitude and nature of trap levels in the gallium arsenide crystal could be determined. EL2 levels at 0.8 and 1.07 eV below the conduction band with a total density of about 1016 cm−3 were seen. Cr appears to form an impurity band at 0.8 eV above the valence band so that with the EL2 level (just below) it brackets the Fermi level. The effect of white light on the front surface of the sample during sub-band-gap scans was also examined and finally the effect of copper doping was studied.
Reply to ‘‘Comment on ‘Phonon fluctuation model for flicker noise in elemental semiconductors’ ’’ [J. Appl. Phys. 5
2, 2884 (1981)]
Authors: Jindal R. P. , van der Ziel A.
Published: July 2002

Phonon fluctuation model for flicker noise in elemental semiconductors is consistent with then existing data. New experimental results may necessitate a reinterpretation of some of the axioms of the model. A further improvement in the model can result by reviewing some of the assumptions involved.
Drift dissipative instabilities between the electron and ion cyclotron frequencies
Authors: Willett Joseph E. , Aktas Yildirim
Published: July 2002

The possible existence of drift dissipative instabilities in an inhomogeneous, collisional plasma with frequencies in the range Ωi ≪Re ω≪Ωe is investigated. It is shown that drift modes associated with lower-hybrid and electron-acoustic waves are stabilized by ion collisional damping when the electrons are cold but that unstable waves can exist when the electrons are warm.
A modification of the mixing length approach to turbulent transport
Authors: Simons S.
Published: July 2002

It is known that the usual development of the mixing length approach to the transport of a passive physical quantity in a turbulent fluid is only valid if the proportional change in concentration of the quantity over a mixing length l is small. In the present paper we formulate a modification of the theory which is not subject to this constraint and proceed to apply it to various cases of interest. The results obtained can differ substantially from those given by the usual approach when the above criterion for the validity of the latter is not satisfied.
Fast switching in a bistable 270° twist display
Authors: van Sprang H. A. , Aartsen R. G. , de Vaan A. J. S. M.
Published: July 2002

It is demonstrated that a bistable electro-optic effect can be obtained in a nematic liquid-crystal configuration having a 270° twist and a 30° boundary tilt. In this effect, which we call Bluebird (blue birefringent display) very rapid switching is possible in one direction, leading to write times of 0.2 ms at 14 V. Furthermore, the necessity is shown of a minimum repetition time of 200–400 ms between two subsequent write-refresh cycles and of a blanking pulse of about 50 ms before writing new information. The effect is compared with other existing bistable nematic liquid-crystal effects and its switching times appear as rather fast for a nematic effect.
Reflection of surface acoustic waves on anisotropic media
Authors: Schiavone P. , Planat M.
Published: July 2002

Reflection of Rayleigh surface waves by shallow grooves or metallic strips on general anisotropic crystals is analyzed. In this paper, the groove or strip is considered as a small discontinuity which acts as a surface excitation source for the scattering of the incident wave. The problem is solved by using Fourier transform technique and integration in the complex plane. Reflection coefficients of the various geometries on quartz and lithium niobate are calculated in good agreement with experiment.
Diffusive gas transport through capillaries: A solution to the intermediate case based upon the kinetic theory of gases
Authors: Moss Arthur Z.
Published: July 2002

Diffusion of gases through porous media is often treated in the continuum approximation of fluid dynamics. However, when the pore diameter is of the same order of magnitude as the mean free path of the molecules in the gas, the continuum approximation is no longer valid because of incorrect collision counting. This paper presents the first theoretical solution of this problem by strict use of the kinetic theory of gases. The diffusion coefficient as calculated herein exhibits a coupling term not present in the continuous fluid treatment.
Characterization of shallow (R
p <20 nm) As- and B-implanted and electron-beam annealed silicon
Authors: McMillan G. B. , Shannon J. M. , Clegg J. B. , Ahmed H.
Published: July 2002

The annealing characteristics of shallow (Rp <20 nm) arsenic- and boron-implanted layers were found to be a complex function of the thermal cycle which the sample experienced. Arsenic at 10 keV and boron at 4.5 keV (derived from 20 keV BF+2 ) were implanted in the dose range 1014–1016 cm−2 into (100) Si. The optimal implant doses to maximize conductivity with essentially undiffused layers of device quality material were 2 × 1015 and 1015 cm−2 for As and B, respectively. A comparison of rapid isothermal annealing using the multiple-scan electron-beam annealing method and conventional furnace annealing was made. For arsenic minimum resistivities of about 2 × 10−4 Ω cm were obtained after furnace annealing at 550 °C for 15 min or electron-beam annealing with a peak temperature between about 700 and 1100 °C during a 100 ms (or 1 s) anneal. For boron, electron-beam annealing for 100 ms (or 1 s) with a peak temperature of between ∼700 and 1000 °C produced a resistivity of 7 × 10−4 Ω cm which compared with 1.2 × 10−3 Ω cm following conventional furnace annealing. High-resolution SIMS showed that peak temperatures of up to about 1000 and 1100 °C for B and As layers, respectively, may be reached with essentially no diffusion. An extension of diffusion theory applicable to conventional furnace annealing of deeper implant gave results in accord with SIMS profiles.
Acoustic emissions from penny-shaped cracks in glass. I. Radiation pattern and crack orientation
Authors: Kim Kwang Yul , Sachse Wolfgang
Published: July 2002

In the first part of this paper we describe measurements of the radiation pattern of the acoustic emission (AE) signals emitted when a penny-shaped crack of Mode I type is generated in a glass plate by pressing a rigid conical indenter onto the surface. It is shown that the orientation of a crack determined from the radiation pattern of the emitted AE signals is in agreement to within several degrees with a direct optical determination.
Elastic precursor decay calculation
Authors: Partom Y.
Published: July 2002

We propose a characteristics scheme to compute the flow field behind the elastic precursor in plane impact. An important feature of the scheme is that the precursor path is one of the lines of the integration net. This enhances the accuracy and flexibility of the scheme. We use the scheme to conduct an extensive parametric investigation of the precursor decay flow field. We show that correct shapes of flow field profiles are reproduced only if a finite rate of dislocation generation is assumed. We demonstrate several effects that contribute to the resolution of the precursor decay anomaly.
Localized epitaxial growth of CrSi2 on silicon
Authors: Shiau F. Y. , Cheng H. C. , Chen L. J.
Published: July 2002

Epitaxial CrSi2 grown on (001) and (011) Si were investigated by transmission electron microscopy. In comparison with the CrSi2 epitaxy previously obtained in (111) Si, the quality of the epitaxial CrSi2 layers, in terms of the size, extent of the silicon surface coverage, and the regularity of interfacial dislocations of the epitaxial regions, were found to be the best in (111) Si and the poorest in (011) Si. The role of the lattice match in the epitaxial growth of CrSi2 on silicon is explored. Crystallographic analysis was carried out to examine possible matches between atoms in the corresponding CrSi2 planes and (111), (001), and (011) Si planes, respectively, at CrSi2/Si interfaces. The quality of CrSi2 epitaxy was found to correlate directly with the lattice match at the interfaces.
Optical properties of quantum wells with ultrathin-layer superlattice barriers
Authors: Ishibashi A. , Mori Y. , Nakamura F. , Watanabe N.
Published: July 2002

Single quantum wells of GaAs with barriers of (AlAs)2(GaAs)2 ultrathin-layer superlattices have been fabricated and photoluminescence measurement was performed. The photoluminescence energy was found to change almost linearly against the well width and the photoluminescence linewidth to get smaller with decreasing well width, which is in marked contrast to the case of a usual alloy-barriered single quantum well. It is indicated that the effective energy gap of the ultrathin-layer superlattice barrier decreases with the decreasing well width in such a structure.
Optical and transient capacitance study of EL2 in the absence and presence of other midgap levels
Authors: Skowronski M. , Lagowski J. , Gatos H. C.
Published: July 2002

A high-resolution optical study was carried out on GaAs crystals grown by horizontal Bridgman and liquid-encapsulated-Czochralski methods. An excellent correlation was found between the intensity of the 1.039-eV no-phonon line and the characteristic absorption of EL2, the major deep donor level in GaAs. A correlation was also found between the characteristic optical absorption of EL2 and its concentration as determined by junction capacitance measurements. The presence of EL0, another midgap level contained in heavily oxygen-doped crystals at concentrations always less than those of EL2, had no effect on the optical spectra, but altered the capacitance measurements. Accordingly, an accurate calibration for the determination of EL2 by optical absorption was obtained from capacitance measurements on crystals containing only EL2; in this way the uncertainties introduced by other midgap levels were eliminated.
Space-charge effect on hole transport in resistive hydrogenated amorphous silicon
Authors: Nishida Toshio , Hoshino Yasushi
Published: July 2002

Hole transport properties of resistive hydrogenated amorphous silicon (1012 Ω cm) are studied by a pulsed photoconductivity technique. Transit time is analyzed by the Scher–Montroll plotting method. Estimation of mobility is done with photocurrent measurement under a space-charge-limited condition, and it is confirmed that the mobility value measured under this condition agrees with the calculated value found from space-charge-limited current. With no space-charge effect, temperature dependence and electric field dependence of transit time is represented by τ=τ0 E−1/α′ exp(Δ/kT).
Observation of silicon self-interstitial supersaturation during phosphorus diffusion from growth and shrinkage of oxidation-induced stacking faults
Authors: Nishi Kenji , Antoniadis Dimitri A.
Published: July 2002

The effects of phosphorus diffusion on the growth and shrinkage of oxidation-induced stacking faults (OSF) has been studied in the temperature range from 950 to 1100 °C. By using Wright etch on angle-lapped samples, OSF size dependence on depth has been obtained. OSF grow faster or shrink slower with increasing phosphorus dose, thus indicating a self-interstitial supersaturation. Moreover, it was found that this supersaturation is not the result of phosphorus precipitation. Silicon self-interstitial concentration normalized to its equilibrium value has been calculated from the OSF kinetics and was compared with time, phosphorus dose, and temperature. It was found that the interstitial supersaturation increases with phosphorus dose and decreases with annealing time. At the same phosphorus deposition condition, the interstitial concentration decreases with increasing temperature. Normalized self-interstitial concentration calculated from enhanced phosphorus diffusivity at the profile tail, assuming a pure interstitialcy phosphorus diffusion mechanism, yields values approximately twice as high as those calculated from OSF kinetics. Possible reasons for this discrepancy are discussed.
Isotopic tracer studies of oxygen transport through SiO2 films at 1000 °C using secondary ion mass spectrometry
Authors: Han C. J. , Helms C. R.
Published: July 2002

Dry oxides (≤8 ppm H2O) grown on Si(100) at 1000 °C at 1 atm using purified 16O2 and purified 18O2 were analyzed using secondary ion mass spectrometry. 18O is observed at the interface, in the bulk of the 16O oxide, and at the surface in agreement with other recent reports. Our results show little lattice diffusion in agreement with Mikkelsen’s work [Appl. Phys. Lett. 45, 1187 (1984)]. A previous report [J. Electrochem. Soc. 131, 1944 (1984)] of appreciable lattice diffusion is due to higher water content.
Attempt to observe Nd:YAG laser-induced nonlinear reflection in cholesteric and cholesteric/nematic mixtures of liquid crystals
Authors: Espinet Héctor , Lesiecki Michael , Ramsburg Michael , Jenkins David
Published: July 2002

We have attempted to experimentally detect a nonlinear reflection in mixtures of cholesteric and cholesteric/nematic liquid crystals induced by Nd:YAG laser pulses. At power densities of up to 4 MW/cm2 (532 nm) and 8 MW/cm2 (1064 nm) we have not observed any optically induced pitch dilation or distortion in these media.
Characterization of disorder and annealing behavior of Si-implanted Ga1−xAlx As with laser Raman spectroscopy
Authors: Kakimoto Koichi , Katoda Takashi
Published: July 2002

Effects of aluminum in Ga1−xAlx As on damage introduced by Si implantation and annealing behavior were studied based on Raman spectra. Increase in aluminum content suppresses the introduction of damage. However, aluminum in Ga1−xAlxAs reduced the concentration of Si in lattice site after annealing.
Metalorganic–vapor-phase-epitaxial growth of Mg-doped Ga1−xAlxAs layers and their properties
Authors: Kozen Atsuo , Nojima Shunji , Tenmyo Jiro , Asahi Hajime
Published: July 2002

Magnesium-doped Ga1−xAlxAs layers are grown by metalorganic vapor-phase epitaxy (MOVPE) on (100)-GaAs substrates using bis-cyclopentadienyl magnesium (Cp2Mg) as the organometallic precursor to Mg. Room-temperature hole concentrations in the range of 1×1017–1×1019 cm−3 are achieved with high controllability. The electrical properties are comparable to those for Zn-doped GaAlAs layers. The Mg acceptor energy Ea increases from 25 meV for an Al composition of x=0 to 42 meV for x=0.7. The x dependence of Ea is smaller than that for Zn. Photoluminescence intensities for GaAs and Ga0.7Al0.3As layers are comparable and increased linearly with hole concentration up to the middle of 1018 cm−3. The Mg diffusion coefficients in GaAs and Ga0.7Al0.3As layers are also similar, and are much smaller than the diffusion coefficient for Zn. These results indicate that Mg is a useful p-type dopant in the MOVPE growth of GaAlAs layers.
Band discontinuities and calculations of GaAs-AlGaAs superlattice structures
Authors: Chomette A. , Deveaud B. , Baudet M. , Auvray P. , Regreny A.
Published: July 2002

The first two optical transition energies of GaAs-Ga(Al)As superlattices and multiquantum wells with small well widths are quite sensitive to the band discontinuity. On a series of samples the parameters of which are determined by x-ray diffraction, we compare the energies measured in photoluminescence and photoluminescence excitation spectroscopies with the results of calculations within the framework of the envelope function approach and with the simple Kronig–Penney model. The envelope function approximation models give transition energies systematically smaller than the experimental values and the discrepancy increases when the well width decreases. With the Kronig–Penney model, both excitonic transitions are satisfactorily calculated for each sample with a conduction-band offset around 75%, but we do not find a unique value of the conduction-band offset for all samples.