bluuebunny/crossref_metadata_2025 huggingface dataset:
Dependence of flat-band voltage of metal-oxide semiconductor structures on phosphosilicate-glass growing conditions
Authors: Masetti G. , Severi M.
Published: February 2003

The flat-band voltage VFB of metal-oxide semiconductor structures stabilized with phosphosilicate-glass (PSG) films is studied as a function of the film deposition conditions. It is found that the PSG layers can induce an alteration in the value of the ’’initial’’ VFB which, however, can be completely eliminated by depositing these layers in a pure nitrogen ambient and annealing them for 10 min at 1100 °C in N2. The results are explained in terms of an oxidation-induced fixed oxide charge model.
Superconducting tunneling junctions of V3Si-SiOx-Mo3Re2
Authors: Tarutani Y. , Yamada K. , Kawabe U.
Published: February 2003

Superconducting tunneling junctions of V3Si-SiOx -Mo3Re2 have been formed by a coevaporation technique. The junctions are shown to have superconducting tunneling characteristics. The junction of this type gives promise of being usable at temperatures of 9–10 K.
Retarded deposition of Li3N thin films on WO3 substrates
Authors: Oi Tetsu
Published: February 2003

Amorphous Li3N thin films are deposited by vacuum evaporation onto both WO3 thin-film and glass substrates. It is found that Li injection into WO3 takes place. This Li injection retards the formation of stable Li3N films on WO3 substrates in the initial stages. Li3N does form a stable film on LixWO3 , i.e., Li-injected WO3, at later stages.
Field-induced phase transitions in phase-II poly(vinylidene fluoride)
Authors: Banik N. C. , Taylor P. L. , Hopfinger A. J.
Published: February 2003

A calculation of the free energy of both the polar and nonpolar forms of phase-II poly(vinylidene fluoride) has been performed by means of a generalized mean-field approximation. The results show the nonpolar form to be lower in free energy than the polar form, and provide a good estimate of the critical electric field necessary to cause the recently observed, nonpolar-polar phase transition in this material.
Low-temperature gettering of Cr in GaAs
Authors: Magee T. J. , Hung J. , Deline V. R. , Evans C. A.
Published: February 2003

Gettering of Cr by back-surface damage has been investigated at temperatures in the range 300–400 °C, for anneal periods of 10–300 h. It has been shown that measurable concentrations of Cr can be detected and that the process can be characterized by an activation energy of ≃0.88 eV and a time-dependent term exp(ϑt1/2).
Effect of plasma reflection on open-circuit voltage of a solar cell at ultrahigh light intensities
Authors: Tewary V. K. , Kothari L. S. , Jain S. C.
Published: February 2003

It is shown that the observed decrease of open-circuit voltage of a silicon solar cell for ruby laser light at intensities beyond 105 W/cm2 can be explained by incorporating the effect of plasma reflection of light from the surface of the solar cell.
Stiffness-controlled variable-acoustic-delay line
Authors: Pappalardo M.
Published: February 2003

This letter describes a simple variable-delay line which makes use of the well-known phenomenon of stiffening of a solid caused by piezoelectricity. In a piezoelectric ceramic bar we emit a Lamb wave which generates an electric field perpendicular to the direction of the wave. Short-circuiting the electric field by joining together certain metal strips placed on one of the two free surfaces of the bar, we obtain a reduction of the velocity dependent on the piezoelectric coupling factor. The delay variation obtained in this way is only 0.013 μsec/mm. However, it can be controlled digitally in quite a simple way by means of an analogical multiplexer. A line of about 70 mm permits a variation of about 1 μsec, which should make it possible to use the device in the field of acoustic visualization for medical diagnostics.
Atomic-interlayer-controlled diffusion at semiconductor-semiconductor interfaces
Authors: Margaritondo G. , Stoffel N. G. , Katnani A. D. , Brillson L. J.
Published: February 2003

We present experimental evidence that the extent of microscopic interdiffusion processes at GaAs-Ge interfaces is strongly affected by ultrathin layers of a reactive metal deposited between the two semiconductors. This modulation can be explained by a recently proposed model in which the activation energies for out-diffusion of the substrate atoms are modified by the dipole field at the metal-semiconductor interface.
Reduction and control of optical waveguide losses in glass
Authors: Findakly T. , Garmire E.
Published: February 2003

Reproducible waveguides were obtained by diffusion of silver films both with and without an applied electric field. Measurements of the mode, wavelength, and thickness dependences of the loss permit us to identify loss contributions from both the diffusant and also from surface roughness. Reduction of loss was achieved both by burying the waveguide below the surface of the substrate and also by performing measurements in the near infrared.
Nonlinear optical properties of N, N′ dimethylurea
Authors: Halbout J.M. , Sarhangi A. , Tang C.L.
Published: February 2003

The performance of a nonlinear organic material, N, N′ dimethylurea, is evaluated through second-harmonic generation in powder. It is shown to be most effective in the region 227–240 nm. The UV absorption of this compound is also reported. The observation of second harmonic generation in this material rules out one of the two crystal structures reported in the literature.
Facet degradation of InGaAsP/InP double-heterostructure lasers
Authors: Morimoto M. , Imai H. , Hori K. , Takusagawa M. , Fukuda M.
Published: February 2003

The facet degradation of InGaAsP/InP double-heterostructure (DH) lasers was studied in water. It was found that the facet degradation of InGaAsP/InP DH lasers is caused by facet oxidation and that the oxidation rate is some orders of magnitude lower than that of GaAlAs DH lasers. Facet degradation is accelerated by the water temperature, while no optical power dependence was exhibited below 6.7 mW/μm2 in this study.
Measurements of stimulated Raman scattering from magnetically confined underdense plasmas
Authors: Watt R. G. , Pietrzyk Z. A.
Published: February 2003

Experimental measurements of stimulated Raman scattering of intense CO2 laser radiation from magnetically confined, underdense hydrogen plasmas are reported. The backscatter has a nonlinear intensity dependence as predicted by theory. The spectral structure is seen to consist of several apparent resonances as opposed to the single resonance of the simple theory. A possible explanation of this fine structure in terms of the physical effect of a density gradient is discussed.
Far-infrared laser frequency modulation by refraction index variation in low-density plasma
Authors: De Marchi A. , Godone A. , Bava E.
Published: February 2003

Experimental results are reported of frequency modulation of an optically pumped far-infrared laser obtained by varying the electron density in an ionized gas plasma confined in a dielectric waveguide external to the laser cavity and electromagnetically coupled to its oscillating mode. A modulation depth of 6 kHz at 403.7 GHz (HCOOH laser line) is reported. This was obtained with a weakly ionized plasma (≈1010 e/cm3) at a gas pressure of 0.1 Torr in a 0.3-m-long cell, with a relative electron density variation of 90%. The modulation bandwidth was determined by plasma recombination time and turned out to be 20 kHz at this pressure in nitrogen.
Whisker Growth induced by Ag photodoping in glassy GexSe1−x films
Authors: Chen C. H. , Tai K. L.
Published: February 2003

The growth and disappearance of crystalline Se whiskers in glassy GexSe1−x films ( with x=0.1 and (1)/(3) ) during the process of Ag photodoping have been studied by electron microscopy. The longitudinal growth direction of the whiskers is found to be parallel to the c axis of the Se hexagonal lattice.
Submicron-resolution eutectic thin-film mask
Authors: Cline Harvey E.
Published: February 2003

A process for fabrication of submicron periodic arrays uses a directionally solidified eutectic thin film as a mask in x-ray lithography. A 2-μthick Pb-Sn eutectic film was directionally solidified on a mica substrate to produce a mask with a minimum linewidth of 0.7 μ. The structure was replicated with contact x-ray lithography. Applications and the ultimate limitation of this process are discussed.
Detection of extended interstitial chains in ion-damaged silicon
Authors: Tan T. Y. , Föll H. , Krakow W.
Published: February 2003

We have carried out a high-resolution electron microscope lattice imaging study of As+ ion-damaged silicon. Along with dislocation dipoles and intermediate defect configurations from which the dislocation dipoles are generated,〈110〉 chain-type defects have also been detected. By image matching of the experimental and calculated micrographs, it is established that about 100% more interstitial silicon atoms were incorporated in the defective chain. A structure model of this defect is proposed wherein a di-interstitial occupying the 〈100〉 split position is incorporated into every available site along a 〈110〉 chain.
Optical parametric amplification in Ti-diffused LiNbO3 waveguides
Authors: Sohler W. , Suche H.
Published: February 2003

Phase-matched optical parametric amplification has been observed for the first time in a guided-wave structure. In 32-nm-long Ti-diffused LiNbO3 channel waveguides amplification of the 1.15-μ line of a cw He-Ne laser and the associated difference-frequency generation were studied. A gain of up to 75% was achieved for the TE10 (pump)–TM00 (signal, idler) mode combination with a peak pump power of ∼200 W, supplied by a tunable pulsed dye laser. An actual coherence length for the parametric interaction of 25 mm was obtained.
All-optical parallel logic operation using fiber laser plate for digital image processing
Authors: Seko Atsuya
Published: February 2003

A fiber laser plate exhibits sharp transition and high contrast. We describe the first demonstration of all-optical parallel logic operations such as A/D conversion and the AND and OR operations important for digital optical computers using the device as an optical switch array.
Single-longitudinal-mode metalorganic chemical-vapor-deposition self-aligned GaAlAs-GaAs double-heterostructure lasers
Authors: Coleman J. J. , Dapkus P. D.
Published: February 2003

Single-mode self-aligned GaAlAs-GaAs double-heterostructure lasers have been fabricated by metalorganic chemical vapor deposition. These devices operate at low current thresholds on a single longitudinal mode and require only a single photolithographic processing step.
High-efficiency energy extraction in backward-wave Raman scattering
Authors: Jacobs Ralph R. , Goldhar Julius , Eimerl David , Brown Steve B. , Murray John R.
Published: February 2003

Pump depletions of 70–75% have been demonstrated for a KrF-laser-driven, methane-gas-filled backward Raman amplifier and are in agreement with predictions of the Frantz-Nodvik saturated-amplifier model. The associated counterpropagating Stokes laser intensity is determined to be ≳3.5 times that of the pump; the corresponding pulse compression ratio is ≈5.
Acoustic-zone-plate variable-illuminating-angle system for acoustic microscopes
Authors: Heidenreich R. D.
Published: February 2003

The scanning acoustic microscope utilizes a beam of fixed angular illumination with large numerical aperture limiting the amount of information that is obtainable. It is suggested that a multizone transducer–spherical-lens configuration can yield a more flexible acoustic illumination source. Numerical calculations indicate that it should be possible to vary the half-angle of the illumination from about 5° to 57°, thus allowing an estimate of the specimen acoustic impedance to be made and critical angles determined experimentally. A fast, programmed microprocessor will be essential for phase-amplitude control of individual zones and signal detection.
Refractory metal silicide formation induced by As+ implantation
Authors: Tsai M. Y. , Petersson C. S. , d’Heurle F. M. , Maniscalco V.
Published: February 2003

Refractory metal silicides WSi2, TaSi2, and MoSi2 have been successfully formed by implanting As+ through the respective metal films deposited on Si. These ion-beam-induced silicides can be formed on 〈100〉 single-crystal Si substrates as well as on polycrystalline Si films. The formation and annealing of these silicides have been studied by He+ backscattering, x-ray diffraction, and sheet resistivity measurements. Apparently both the ion beam bombardment and some elevation of temperature during implantation are essential for silicide formation. Annealing these ion-beam-induced silicides reduces their resistivity and changes their crystallographic structure. The redistribution of implanted As is also observed.
Damage gettering of Cr during the annealing of Cr and S implants in semi-insulating GaAs
Authors: Vasudev P. K. , Wilson R. G. , Evans C. A.
Published: February 2003

Chromium depth distributions have been measured in Cr-doped GaAs as a function of annealing temperature from 650 to 850 °C under an SiO2 encapsulation for samples implanted with either S or Cr. Following a 650 °C/20-min anneal, the Cr is ’’gettered’’ into two regions of residual damage, one peaked at ∼0.85 Rp and one peaked at about Rp +1.5ΔRp and with integrated densities proportional to the implant fluences. As the anneal temperature is increased, the integrated densities of Cr under these two damage peaks and a third deeper one observed under S implants decrease exponentially following an Arrhenius-type mechanism with activation energies of approximately −1.8, −0.87, and −0.4 eV, respectively. These results are shown to be consistent with a simple thermodynamic model for the formation (association) of Cr defect complexes under the damage peaks. Theoretically estimated binding energies of the complexes are consistent with the experimental activation energies.
In0.53Ga0.47As photodiodes with dark current limited by generation-recombination and tunneling
Authors: Forrest S. R. , Leheny R. F. , Nahory R. E. , Pollack M. A.
Published: February 2003

We report on low-dark-current IN0.53GA0.47As photodiodes in which generation-recombination current dominates diode leakage up to as high as 100 V. At higher voltages, tunneling currents become dominant, resulting in the soft breakdown characteristic widely observed in these materials. The dark current versus voltage characteristics have been fit to variations in current of over six orders of magnitude and a temperature range greater than 150 K using a theory which includes generation-recombination, tunneling, and shunt components.
Switching phenomena in thin-insulator metal-insulator-semiconductor diodes
Authors: Hayashi Yutaka
Published: February 2003

Switching phenomena with current-control-type negative resistance characteristics were observed in thin-insulator metal-insulator-semiconductor diodes made on n-type (100) silicon substrates. The characteristics except breakover point are reproducible and the diodes are also switched from a low-conduction state into a high-conduction state under a fixed-bias condition by light stimulation from a commercial light-emitting diode. One of the possible origins of this negative resistance is carrier multiplication by high-energy electrons tunneled through the thin insulator and injected into the surface of the n-type silicon substrate.
Matrix-addressed analog ferroelectric memory
Authors: Lemons R. A. , Grogan J. K. , Thompson J. S.
Published: February 2003

A ferroelectric gadolinium molybdate crystal can be readily configured with multiple parallel domain walls. An individual domain wall is selectively moved by applying sufficient voltage to a corresponding stripe electrode on one face of the crystal. The polarization current which accompanies this motion is modulated by patterning the electrode on the opposite face of the crystal. In this way segments of analog information stored as a waveform pattern in the electrode can be selectively read. Sounds, words, or segments of typical speech are stored at a density of 50 sec of speech per cm2. The information is formatted in many parallel channels which are addressed with external switches. We have demonstrated this matrix addressing concept in a device which reproduces the words for the digits 0–9 and the symbols * and ♯.
Saturation spectroscopy with multiple-frequency excitation
Authors: Kramer G. , Roy D. N. Ghosh , Helmcke J. , Spieweck F.
Published: February 2003

Signal strength in saturated absorption spectroscopy can be increased without excessive line broadening by using multiple-frequency excitation. This is demonstrated experimentally by phase-modulating the incident laser beam in an electro-optic crystal.
A compact repetitively pulsed superatmospheric-pressure CO2 laser with high output power density
Authors: Dyer P. E. , Tait B. L.
Published: February 2003

The design and operation of a compact superatmospheric-pressure CO2 laser operating at ⩽50 Hz is described. At 5 atm single-mode power densities of 300 MW l−1 have been achieved at 25 Hz using a simple excitation circuit with low charging voltage.
Evidence of mode sweeping effects in a rotating-mirror Q-switched transversely excited atmosphere CO2 laser
Authors: Chatterjee U. K. , Shikarkhane N. S. , Nundy U.
Published: February 2003

In a rotating-mirror Q-switched transversely excited atmosphere (TEA) CO2 laser the oscillating mode transversely sweeps the gain medium during buildup. This has a pronounced effect on the resulting pulse shape. The tail following the spike is typically in the form of a flat plateau. The experimental conditions favoring the generation of such pulse shapes are indicated. With a very simple device one can generate either a spike or a rectangular pulse from these pulses.
High-energy subnanosecond pulse amplification in XeCl
Authors: Pacala Thomas J. , Laudenslager James B. , Christensen C. P.
Published: February 2003

Pulse slicing and two-pass amplification are investigated as a means of producing high-energy subnanosecond pulses in the near ultraviolet. A simple laboratory-scale XeCl oscillator–Pockels cell pulse slicer–amplifier system is used to produce 50-mJ pulses of subnanosecond duration at 308 nm. Comparison of multinanosecond and subnanosecond pulse amplification allows estimation of the amplifier energy storage time to be 5 ns and demonstrates nearly complete extraction of available stored energy by the subnanosecond pulse.
Picosecond pulses from an optically pumped ribbon-whisker laser
Authors: Duguay M. A. , Damen T. C. , Stone J. , Wiesenfeld J. M. , Burrus C. A.
Published: February 2003

Picosecond pulses have been generated by an optically pumped GaAs laser. The laser consisted of a Zn-doped single-crystal GaAs ribbon whisker 1–2 μm thick sandwiched between highly reflecting dielectric mirrors, thus forming a cavity 5–7 μm long, with a round-trip time of 0.08 ps. Output pulses as short as 1 ps were measured by means of a sum-frequency cross correlation technique.
Iodine monofluoride emission spectrum and formation kinetics in electron-beam-produced plasmas
Authors: Hutchison S. B. , Eden J. G. , Verdeyen J. T.
Published: February 2003

Intense blue-green fluorescence from a structured band centered at λ∼484 nm has been observed from Ar, CF3I, and NF3 (or F2) gas mixtures (T=300 K) excited by a ∼3-ns FWHM electron beam. This emission is tentatively assigned to the E→A3π1 transition of the iodine monofluoride (IF) molecule. From the temporal behavior of the IF* and I2* (342 nm) emission, it has been determined that the IF (E) level is formed primarily by excitation transfer from I* (4P) states. The fluorescence efficiency of the IF (E→A) band and the IF* (E) state radiative lifetime have been estimated to be ∼6% (in 99.83% Ar/0.13% CF3I/0.04% NF3 mixtures. PTOTAL≈2300 Torr) and ∼15 ns, respectively. The emission band structure, the short IF (E) radiative lifetime, and the Franck-Condon shift between the E and A states suggest that IF* is an attractive candidate for a blue-green laser.
Effect of electric field on deep-level transients in GaAs and GaP
Authors: Makram-Ebeid S.
Published: February 2003

For large enough electric fields, the emission of carriers from a deep level in a semiconductor is dominated by a tunneling mechanism. This mechanism is very sensitive to the parameters S and h/ω describing the interaction of the deep level with vibronic modes of the lattice. A best-fit method is used to yield agreement between the theoretical and experimental dependence of the emission rate on electric field and temperature. This is done for levels E3 and EL2 (’’O’’ level) in GaAs and for the ZnO center in GaP. The best-fit values obtained for S and h/ω are found to be consistent with other estimates deduced independently from photocapacitance, luminescence, and electron capture cross section measurements.
Thin-film electroluminescence in impurity-doped Al2O3
Authors: McCarthy S. L. , Lambe John
Published: February 2003

The discovery of a new thin-film electroluminescence system based on impurity-doped anodic aluminum oxide is reported. Average brightnesses of 30 f L have been observed for devices at room temperature operating at 1 kHz biased at 60 V rms, resulting in 7 mA electronic current and a 10% duty cycle. A new stabilizing layer of manganese oxide permits long-term operation without catastrophic breakdown. While electrical stability is achieved, loss in electroluminescence efficiency is apparent, possibly due to electromigration of the impurity ions.
100-GHz Gunn diodes fabricated by molecular beam epitaxy
Authors: Haydl W. H. , Smith S. , Bosch R.
Published: February 2003

Epitaxial GaAs layers of high purity suitable for Gunn devices have been grown by molecular beam epitaxy. Layers with a carrier concentration in the 1015-cm−3 range and a mobility of 5–7000 cm2 V−1 s−1 (300 K) have been used to develop integral-heat-sink millimeter-wave Gunn diodes in the 50–110-GHz range. To date we have obtained cw rf outputs of 10 mW at 100 GHz and 4 mW at 110 GHz.
Temperature dependence of intergrain barriers in polycrystalline semiconductor films
Authors: Orton J. W. , Goldsmith B. J. , Powell M. J. , Chapman J. A.
Published: February 2003

The Petritz theory of Hall mobility in polycrystalline semiconductor films predicts that μH=μ0 exp(−φb/kT) where φb is the intergrain barrier height and μ0 depends only weakly on temperature. Careful examination of experimental results in the literature reveals that, in practice, μ0 varies strongly with φb, an anomaly which can be understood if φb is temperature dependent. We present the results of Hall and resistivity measurements on CdS films which support this interpretation and yield a value for the temperature coefficient α=(1/φb)∂φb/∂T=−0.0022 K−1. This compares with a value of α≃−0.003 K−1 reported by Seager and Pike for silicon bicrystals.
A technique for producing epitaxial films on reuseable substrates
Authors: McClelland R. W. , Bozler C. O. , Fan J. C. C.
Published: February 2003

Using a new technique, which we have named the CLEFT process (cleavage of lateral epitaxial films for transfer), we have grown single-crystal GaAs films by vapor phase epitaxy (VPE) on reusable GaAs substrates. A carbonized photoresist mask with narrow, widely spaced stripe openings is first deposited on a (110) GaAs substrate. Epitaxial growth initiated within the openings, followed by lateral growth over the mask, produces a continuous single-crystal GaAs film. The upper surface of the film is bonded to a glass substrate, and the film is then cleaved from the GaAs substrate, leaving the surface of the latter in condition for repeating the procedure. The same GaAs substrate has been used for successive growth of four GaAs films, each about 4 cm2, ranging in thickness from 5 to 10 μm. The electrical properties of a CLEFT film were found comparable to those of conventional VPE layers. The CLEFT process should also be applicable to other semiconductors.
Residual damage to an atomically cleaned low-temperature-annealed Si(100) surface
Authors: Yamada Isao , Marton Denes , Saris Frans W.
Published: February 2003

A study of the residual damage to an atomically clean Si(100) surface obtained by low-energy ion sputtering followed by low-temperature annealing has been made. For the sputtering Ne, Ar, and Kr ions were used in the 1–4-keV energy range. The surface was annealed at a temperature of 720 °C. Residual damage to atomically clean Si surface was evaluated by excess-minority-carrier surface lifetime, and Rutherford backscattering measurements combined with channeling measurement. Residual damage to the Ar-sputtered and annealed surface was higher than that for the other gases.
Reciprocity between the reflection electron microscope and the low-loss scanning electron microscope
Authors: Wells Oliver C.
Published: February 2003

The reflection electron microscope image—or, more correctly, the dark-field image from a solid specimen in the transmission electron microscope—has certain similarities to the low-loss electron image in the scanning electron microscope. These methods are reciprocal in the sense that it is possible to establish an equivalence by reversing the direction of the electrons through the system. In both cases the scanning version is better suited for imaging by means of wide-angle scattering events, while the nonscanning version is better suited for diffraction contrast. The equivalence between these two methods can be established by either a wave-optical or a geometrical argument.
Reduction of scattering from a glass thin-film optical waveguide by CO2 laser annealing
Authors: Dutta Subhadra , Jackson Howard E. , Boyd J. T.
Published: February 2003

Laser annealing with a CO2 laser is utilized to improve the quality of Corning 7059 glass thin-film optical waveguides. The 1.0-μm-thick 7059 glass film is deposited by sputtering onto a thermally oxidized silicon substrate. Measurement of the absorption coefficient of 7059 glass at λ = 10.6 μm yields a value of 1.12 x 104 cm−1. Dark-field photomicrographs taken before and after laser annealing imply that both surface defects and bulk inhomogeneities are removed by laser annealing. Waveguide attenuation is measured to be 17.4 dB/cm befor laser annealing and 0.6 dB/cm afterwards.
Fast frequency modulation of a far-infrared laser with a Schottky barrier diode
Authors: Godone A. , De Marchi A. , Bava E.
Published: February 2003

Fast frequency modulation of a far-infrared laser by means of the varactor effect in a micron-size Schottky barrier diode is presented. A cavity tuning experiment carried out with the optically pumped HCOOH line at 403.7 GHz and a Pt–n-GaAs diode is described. Modulation depth of about 15 kHz with a bandwidth of approximately 2 MHz has been achieved.
Elimination of dispersion-induced distortion in infrared absorption spectra by use of photoacoustic spectroscopy
Authors: Laufer G. , Huneke J. T. , Royce B. S. H. , Teng Y. C.
Published: February 2003

Fourier transform infrared photoacoustic techniques have been employed to remove the spectral distortion present in the transmission and reflectance spectra of powdered solids suspended in mulls and pressed pellets. Results are presented for AgCN. The photoacoustic data is also compared to that obtained by Raman spectroscopy.
Low-temperature redistribution of Cr in boron-implanted GaAs in the absence of encapsulant stress
Authors: Magee T. J. , Lee K. S. , Ormond R. , Evans C. A. , Blattner R. J. , Hopkins C.
Published: February 2003

Motion and gettering of Cr into damage regions of B-implanted GaAs samples has been investigated using transmission electron microscopy and secondary-ion mass spectrometry profiling. In the absence of an encapsulant layer, redistribution and gettering of Cr has been detected within the implanted region after annealing at temperatures from 300 to 600° C. The observed gettering behavior can be correlated with the development of damage in the form of dislocation loops of 50 Å average image diameter. The motion of Cr into damage produces sharply defined zones of Cr depletion which appear stable at 600° C.
Measurement of concentrator solar cell series resistance by flash testing
Authors: Chaffin R. J. , Osbourn G. C.
Published: February 2003

A simple technique for the measurement of series resistance of concentrator solar (photovoltaic) cells is described. This technique makes use of the fact that the ’’short circuit’’ current of a solar cell as a function of light intensity will begin to saturate at an intensity determined by the series resistance of the cell and circuit. In this region the series resistance of the cell can easily be found from a measurement which is relatively independent of illumination intensity and spectrum. Experimental data are presented that verify this result.
Thermal oxidation of hafnium silicide films on silicon
Authors: Murarka S. P. , Chang C. C.
Published: February 2003

Hafnium silicide films on silicon substrates were oxidized in dry oxygen or in oxygen bubbled through boiling water in the temperature range 400–1000 °C. The progress of the oxidation was followed by measuring the conductivity of the specimen and by Auger analysis. Hafnium silicide films oxidized rapidly even at temperatures below 700 °C; for example, at 700 °C a∼1400-Å silicide film was completely oxidized in 20 min. This oxidation behavior is distinctly different from that of most other silicides on silicon which tend to grow SiO2 instead of the oxidized silicide. The oxidized silicide film inhibited further oxidation of the silicon substrate in dry oxygen but not in steam.
Silicon/metal silicide heterostructures grown by molecular beam epitaxy
Authors: Bean J. C. , Poate J. M.
Published: February 2003

Epitaxial NiSi2 and CoSi2 layers have been grown on crystalline silicon by molecular beam epitaxy (MBE). Stoichiometric, highly crystalline films can be grown by either silicon-metal codeposition or by pure metal deposition on substrates heated to 550–800 °C. Crystalline quality is relatively insensitive to deposition conditions. Film smoothness is maximized by codeposition at temperatures near 600 °C. Both silicides have been epitaxially overgrown with silicon producing a fully crystalline silicon/metal silicide/silicon heterostructure.
Hard axis anisotropy of Pr2Co17 detected by single-point detection technique
Authors: Bolzoni F. , Leccabue F. , Pareti L.
Published: February 2003

We performed a computer experiment verifying the singular point detection theory in the case of a hard axis polycrystalline isotropic ferromagnet. We applied this theory to the easy plane sample Pr2Co17 and succeeded in measuring its anisotropy field. The measurements were carried out in the 115–297 K temperature range by means of a pulsed field apparatus.
Laser annealing and selective magnetization of manganese-aluminum alloys
Authors: Herbst J. F. , Chraplyvy A. R. , Croat J. J.
Published: February 2003

MnxAl1−x alloys (0.5⩽x⩽0.6) and related materials feature a phase transition from an essentially nonmagnetic state to a state having large magnetization. The transition is generally induced by appropriate conventional annealing. We demonstrate that a modest-power laser is also capable of bulk annealing. More importantly, focused laser radiation can be used to anneal preselected portions of a sample, thus introducing small, hard magnetic regions into an otherwise nonmagnetic host. Tailoring of magnetic devices and information storage are potential areas of application.
Fast ion transport in silver halide solid solutions and multiphase systems
Authors: Shahi K. , Wagner J. B.
Published: February 2003

The incorporation of homovalent ions, e.g., I− in AgBr, leads to a substantial increase in ionic conductivity σ. The charge compensation concept does not explain the enhancement. AgBr+30 mol. % AgI exhibits σ∼7 Ω−1 cm−1 at 380 °C, which is ∼170% larger than that of α-AgI, the best known supersonic conductor, at its melting point. The purely elastic displacement caused by the foreign ion is suggested to be the origin of such a unique behavior. Furthermore, AgI-AgBr two-phase systems display σ∼103 times higher than predicted by the classical theories.
Performance of i
n s
i
t
u superconductors in solenoids
Authors: Ostenson J. E. , Finnemore D. K. , Verhoeven J. D. , Gibson E. D.
Published: February 2003

A series of small solenoids have been wound from in situ prepared Nb3-Sn-Cu superconducting wire in order to determine the suitability of these materials for magnets which require bending strains greater than 2% at the surface of the wire. In the range from 4 to 14 T, Jc of the solenoid is equivalent to or exceeds performance for unstrained material. For best performance in ac fields, it is essential to twist the wire and to support the windings with a potting material. Calorimetric measurements of the ac losses in the 8–12 T range give 1 mW/cm3 for magnetic fields ramped at 1 T/s.
Further improvements in the efficiency of low-energy positron moderators
Authors: Mills Allen P.
Published: February 2003

Low-energy positrons are emitted by negative-positron-affinity moderator surfaces irradiated by the β+ spectrum of a radioactive source. The slow-positron conversion efficiency ε (flux of slow positrons/total β+ activity) of a Cu(111) single-crystal moderator increases 30% when the positron affinity is made more negative by exposure of the Cu to H2S in situ. Upon cooling the moderator crystal to 100 K, ε increases an additional 50% to ε=(1.5±0.3)×10−3 using a low-self-absorption β+ source in a backscattering geometry.
Epitaxial alignment of polycrystalline Si films on (100) Si
Authors: Tsaur B. Y. , Hung L. S.
Published: February 2003

We demonstrate that fine-grained polycrystalline Si films obtained by chemical vapor deposition can be aligned expitaxially with respect to the underlying (100) Si substrate upon furnace annealing at temperatures of 1000–1150 °C. The alignment proceeds basically by the formation of epitaxial columns which subsequently grow laterally to consume the remaining polycrystalline Si. The rates of alignment are measured to be 20–200 Å/min in the temperature interval of annealing with an activation energy of 4.7 eV. The epitaxial layers so obtained are of reasonably good crystal quality and contains only a small amount of planar crystallographic defects.
Observation of asymmetric electric field around laser-imploded target
Authors: Shiraga H. , Mochizuki T. , Yamanaka C.
Published: February 2003

Strong anisotropy on angular distribution of alpha particles in D-T reaction was observed in locally irradiated exploding pusher mode compression. This indicates asymmetric generation of an electric field localized around the laser irradiated spots whose scale length and shape were estimated to be about 300 μm and radially extended from the irradiated spots.
Electron diffraction studies of Ag photodoping in GexSe1−x glass films
Authors: Chen C. H. , Tai K. L.
Published: February 2003

GexSe1−x glass films (with x=0.1 and 0.33) when immersed in an Ag-containing solution such as KAg(CN)2 show additonal sharp polycrystalline diffraction rings which can be identified as due to the formation of crystalline domains of Ag2Se and its oxide. These polycrystalline rings are found to disappear gradually with increasing UV exposure. Typical UV exposure time required to make the polycrystalline pattern disappear is ∼20 sec for x=0.33 and 2 sec for x=0.1 with power incident at the sample ∼70 mW/cm2.
Enhancement of second-harmonic generation in LiNbO3 crystals with periodic laminar ferroelectric domains
Authors: Feng Duan , Ming Nai-Ben , Hong Jing-Fen , Yang Yong-Shun , Zhu Jin-Song , Yang Zhen , Wang Ye-Ning
Published: February 2003

Using the Czochralski method we have grown LiNbO3 crystals with periodic laminar ferroelectric domains whose half-period nearly corresponds to the coherence length. Quasi-phase-matching for the nonlinear optical coefficient d33 has been approximately realized and enhancement of second-harmonic generation relative to conventionally phase-matched crystals of the same length has been observed.
Conductivity changes in dehydrogenated and rehydrogenated discharge-produced a-Si:H
Authors: Staebler D. L. , Pankove J. I.
Published: February 2003

The dark and photoconductivity of a-Si:H was measured after in- and out-diffusion of hydrogen. The results agreed with the expected variations in the density of uncompensated dangling bonds. Secondary-ion mass spectrometry profiles confirmed the changes in hydrogen concentration. Samples doped with phosphorus behaved differently from undoped samples. Annealing above 400 °C quenched the optically induced conductivity changes found in a-Si:H.
Pulse annealing deficiencies in GaAs
Authors: Davies D. Eirug , Lorenzo J. P. , Ryan T. G.
Published: February 2003

Heavily doped epitaxial GaAs has been subjected to pulse electron beam annealing. Differential Hall measurements indicate that the annealing causes a reduction in the majority carrier density and severely curtails the carrier mobility. The thickness of such affected material is increased with any subsequent heat treatment. These results suggest that compensating defects are produced by the pulse annealing and that these migrate inwards from the surface during thermal annealing. It is considered that such defects account for the general failure to activate low-dose implants, the loss of high-dose activation with moderate heat treatment, and the invariably poor mobilities within pulse-annealed implanted layers.
Effect on electrical properties of segregation of implanted P+ at defect sites in Si
Authors: Sadana D. K. , Strathman M. , Washburn J. , Magee C. W. , Mäenpää M. , Booker G. R.
Published: February 2003

The aim of this work was to study the furnace annealing behavior of buried amorphous layers formed due to P+ implantation into Si and to investigate the effects of annealing on the electrical properties of the implanted layer. For this purpose, P+ was implanted into (111) Si in a non-channeling direction at 120 KeV to a dose of 3 × 1014/cm2 at RT. The implanted samples were subsequently annealed at 750° C. 90° cross-sectional transmission electron microscopy (TEM), MeV He+ channeling, secondary-ion mass spectrometry (SIMS), and electrical results were obtained from the same specimen. The TEM results showed that the annealing at 750° C resulted in the formation of two discrete damage layers at depths of 600 and 1100Å. However, the MeV channeling measurement indicated the presence of three damage regions; the third region being beyond the second damage layer observed by TEM. The SIMS measurements showed pronounced ’’pileups’’ of phosphorus atoms at three damage regions. The carrier-concentration profile followed the atomic distribution curve. However, the mobility profile showed decreases only at the two deeper-lying regions.
Gain and saturation intensity measurements of a mode-locked KrF oscillator-amplifier
Authors: Banic J. , Efthimiopoulos T. , Stoicheff B. P.
Published: February 2003

The gain and saturation intensity of a fast-discharge KrF oscillator-amplifier have been investigated. The small-signal-gain coefficient was found to be 0.145 cm−1 for a 2-ns pulse and 0.160 cm−1 for a 10-ns pulse, with the respective saturation intensities ∼1.6 and ∼2.0 MW/cm2. An energy of 250 mJ was extracted with a 10-ns input pulse. It was possible to isolate by amplification a single 2-ns pulse from a mode-locked train (of 2 or 3 pulses) and to extract 35 mJ in the amplified beam.
Zinc-oxide–on–silicon surface acoustic wave resonators
Authors: Martin S. J. , Gunshor R. L. , Pierret R. F.
Published: February 2003

The first surface acoustic wave resonators fabricated using a ZnO-on-Si layered structure are described and characterized. The optimum location of the transducers in the resonant cavity and the general performance are first cited for devices containing isoloated aluminum, isolated Cr/Au, and shorted Cr/Au reflector strips. The transmission characteristics and reflecting properties of the shorted Cr/Au configuration are then examined in more detail. An unloaded Q of 3100 has been obtained with the shorted Cr/Au configuration at a resonant frequency of 105.4 MHz.
Multicolor fluorescent liquid-crystal display concepts
Authors: Sato S. , Labes M. M.
Published: February 2003

A cholesteric liquid-crystal electro-optic cell is described which functions as both a UV shutter and as a tunable fluorescent emitter (’’shutter cell’’). By interfacing such a cell with an external passive fluorescent element, a two-color display can be achieved. Contrast ratios of about 5 in the two-color pairs blue-green, blue-red, and green-red are achievable by electrically switching the shutter cell. Multicolor displays can be made by stacking shutter cells and passive elements.
GaInAsP/InP stripe-geometry laser with a reactive-ion-etched facet
Authors: Coldren L. A. , Iga K. , Miller B. I. , Rentschler J. A.
Published: February 2003

We report the first use of reactive-ion etching (RIE) to form mirror facets on GaInAsP/Inp double-heterostructure (DH) lasers (λ∼1.3 μm). The RIE, performed with a Cl2:O2 gas mixture, provides vertical etched walls with no undercutting. Initial laser results demonstrate that quasi-single-mode operation and reasonable threshold currents are possible.
〈 ρR〉 measurements in ion fusion targets with a fast-proton beam probe
Authors: Fisher T. R. , Perez J. D.
Published: February 2003

A technique for measurement of 〈 ρR〉 in ion fusion targets is proposed which determines the contribution of both pusher and fuel independently by measuring both the energy loss and angular spread of a fast-proton beam after passage through the target. Some model calculations are presented which illustrate the potential accuracy of this technique.
Glow discharge preparation of amorphous hydrogenated silicon from higher silanes
Authors: Scott B. A. , Brodsky M. H. , Green D. C. , Kirby P. B. , Plecenik R. M. , Simonyi E. E.
Published: February 2003

Amorphous hydrogenated silicon has been deposited by plasma decomposition of Si2H6 and Si3H8. A major feature of the process is a deposition rate enhancement of over a factor of 20 compared to monosilane. The resulting films are compositionally similar to monosilane-produced intrinsic a-Si(H), but films deposited at 300 °C substrate temperature show greater photoconductivity. On the basis of our deposition experiments and the known thermolysis chemistry of the silanes, a conjectural model for the deposition process is presented.
Deep-level traps in low-dose boron-implanted and low-temperature annealed silicon
Authors: Mitić A. , Sato T. , Nishi H. , Hashimoto H.
Published: February 2003

The electronic defect levels in low-dose (1–8×1012 cm−2) B-implanted Si after annealing at 550 °C are measured by the deep level transient spectroscopy method. The defects, which distribute in accordance with the B profile, are assigned to interstitial- and vacancy-boron complexes; Ev +0.27 and Ev +0.43 eV, and Ev +0.47 eV, respectively. In contrast with these defects, a uniform distribution in the implanted layer is observed for Ev +0.56 eV, which is assigned to a divacancy and/or vacancy cluster. Other defects of which the energy levels are very close to those of interstitial- and vacancy-oxygen complexes are also observed.
A new apparatus for multilayer growth by chemical vapor deposition: The sliding-boat close-spaced technique
Authors: Yoshikawa Akihiko , Yoshihara Seiji , Kasai Haruo , Nishimaki Masao
Published: February 2003

A new apparatus for multilayer growth by chemical vapor deposition, the sliding-boat close-spaced tecnique (SBCST), is presented. The structure of the SBCST growth apparatus is quite similar to that of the conventional liquid phase epitaxy sliding-boat. The possibility of obtaining thin multilayer films by SBCST is shown. Preliminary experimental results for its application to the growth of n-CdS/p-InP heterojunction solar cells are also shown.
Growth of high-quality epitaxial GaAs films by sputter deposition
Authors: Barnett S. A. , Bajor G. , Greene J. E.
Published: February 2003

Epitaxial GaAs films have been grown on (100) Cr-doped GaAs substrates by sputter deposition from an undoped GaAs target. Unintentionally doped samples were high resistivity (105–106 Ω cm) n type with room temperature mobilities as high as 5000 cm2/V sec. Residual oxygen and carbon contamination was minimized through the use of a liquid-nitrogen-cooled shroud surrounding the discharge during deposition. Excess arsenic was provided to the growing film from an effusion cell. Film doping was accomplished using either an evaporated source (Mn) or the addition of a gas-phase impurity (H2S) during sputter deposition. Mn-doped p-type films were grown with room-temperature carrier concentrations between 1.3×1017 and 2.5×1018 cm−3 and corresponding hole mobilities of 240–95 cm2/V sec. The S-doped films were n-type with S concentrations, as determined by secondary-ion mass spectrometer (SIMS), up to the solid solubility limit and sharp doping profiles with widths of ∼200 Å. In all cases the dopant incorporation probability was controllable by varying the negative bias on the growing film.
Interfacial layer formation in the sputter-deposited SiO2/GaAs system
Authors: Torikai Toshitaka , Endo Kenji
Published: February 2003

The sputter-deposited SiO2/GaAs interface has been studied by Auger sputter profiling. An interfacial layer is formed even at about 300 °C whenever SiO2 is deposited on the air-cleaved GaAs surface. On the other hand, when GaAs is cleaved in the sputtering chamber just prior to SiO2 deposition, an interfacial layer is not formed even after annealing at 600 °C, and furthermore the interface is abrupt. Interfacial layer formation is attributed to the existance of thin natural oxide on the GaAs surface.
High-quality submicron niobium tunnel junctions with reactive-ion-beam oxidation
Authors: Kleinsasser A. W. , Buhrman R. A.
Published: February 2003

A new reactive-ion-beam oxidation technique has been applied to the fabrication of rugged, high-quality niobium-lead alloy Josephson tunnel junctions. Control of critical current density over a wide range is possible, and critical current densities exceeding 106 A/cm2 have been obtained. In addition, a process-compatible edge geometry has been developed which allows a junction to be formed on the faceted edge of a niobium base electrode, yielding devices with areas of 10−9 cm2 using 1-μm photolithography.
Laser-induced transient excitation of conducting targets
Authors: Peake William H. , Meadors John G. , Poirier Michael A.
Published: February 2003

A fast-rise time laser pulse of low energy is focused on the surface of a conducting object. The thermionic emission from the irradiated spot constitutes a transient current monopole normal to the conductor surface. This current source excites surface currents in the conducting object, which then radiates a pulse of electromagnetic energy.
Avalanche multiplication and noise characteristics of low-dark-current GaInAsP/InP avalanche photodetectors
Authors: Diadiuk V. , Groves S. H. , Hurwitz C. E.
Published: February 2003

High-performance avalanche photodiodes responding out to 1.25 μm have been fabricated in inverted-mesa n+-InP/n-GaInAsP/n-InP/p+-InP structures. Uniform avalanche gains of 700, dark current densities of 3×10−6 A/cm2 at M=10, and an excess-noise factor of ∼3, also at M=10, have been measured. The low dark current results from the placement of the p-n junction in the InP and from the use of a new passivation technique. Pulse-response rise times, measured with an avalanche gain of 40 and limited by the rise time of the mode-locked Nd:YAG laser pulse, were less than 160 psec.
Surface flaw detection in structural ceramics by scanning photoacoustic spectroscopy
Authors: Khandelwal P. K. , Heitman P. W. , Silversmith A. J. , Wakefield T. D.
Published: February 2003

Laser-scanned photoacoustic spectroscopy has been used to detect tightly closed surface flaws in three types of silicon-base structural ceramic materials. The amplitude of the photoacoustic signal was found to be greater for silicon nitride materials. The repeatability of detecting and locating flaws was excellent both in terms of the amplitude of the photoacoustic signal and signal-to-noise ratio.