bluuebunny/crossref_metadata_2025 huggingface dataset:
An ion beam technique for the measurement of deuterium diffusion coefficients
Authors: Lewis M. B. , Farrell K.
Published: February 2003

This letter describes how a combination of the techniques of nuclear microanalysis and cathodic hydrogenation has been used to determine the diffusion coefficient of dueterium in austenitic stainless steel at room temperature. Samples charged in deuterated acid solutions to levels of about 20 at. % deuterium were quickly transferred to a scattering chamber where a depth profile of the near-surface deuterium was measured. For charging times much longer than the transfer plus anlyzing time, the deuterium profile could be described by an error function at the specimen surface. A diffusion coefficient was determined by a χ-squared test fitting procedure and shown to be consistent with values reported for other methods measured at higher temperatures.
Fatigue-life improvement by nitrogen-ion implantation on steel: Dose dependence
Authors: Lo Russo S. , Mazzoldi P. , Scotoni I. , Tosello C. , Tosto S.
Published: February 2003

The effect of 30-keV nitrogen-ion implantation on the fatigue lifetime of type 38 NCD4 steel has been investigated. The implants enhance the fatigue lifetime for nitrogen doses between 1017 and 2×1017 ions/cm2. The results suggest that the implantation current density can have an important role, in connection with the thermal diffusion of implanted ions.
Quantitative analysis of interfacial impurities using secondary-ion mass spectrometry
Authors: Williams Peter , Baker Judith E.
Published: February 2003

A new secondary-ion mass spectrometry technique is described which permits quantitative analysis of impurities at buried interfaces. The technique utilizes the cascade mixing which accompanies sputtering to mix, and dilute, interfacial impurities into the surrounding matrix to such an extent that ion yields through the interface region are constant and characteristic of the matrix. Comparison with ion-implanted standards then yields analyses accurate to better than 30% (limited by knowledge of the standards) with a statistical uncertainty of 2%.
Pressure dependence of the superconducting transition temperature of Cu40Zr60 and Pd30Zr70 amorphous alloys
Authors: Willer J. , Fritsch G. , Lüscher E.
Published: February 2003

The pressure dependence of the superconducting transition temperature of Cu40Zr60 and Pd30Zr70 metallic glasses is determined by resistance measurements up to 10.8 GPa (108 kbar). Tc is found to increase with pressure in both systems.
Soft x-ray emission from He2+-Li collisions
Authors: Barrett J. L. , Leventhal J. J.
Published: February 2003

Lyman α and Lyman β from excited He+ formed in 60–4000-eV (c.m.) He2+-Li collisions have been observed using a crossed-beam apparatus. The data show that He+(3l) is the predominant reaction product. The maximum measured cross section for production of He+(3l) is ∼11 Å2 at about 1300 eV relative energy.
Time-of-flight atom-probe study of a W-Zr field emitter
Authors: Sakurai Toshio , Kuk Y. , Robertson G. , Marlow G. , Murarka S. P.
Published: February 2003

Our high-performance time-of-flight atom probe was employed successfully in the composition analysis of zirconiated tungsten field emitters. Surface compositions were analyzed in situ under various emitter surface conditions with a mass resolution m/Δm≳2000. Our study showed that nitrogen, instead of oxygen, may play a dominant role in the surface reaction and causes the buildup of pure tungsten in the (100) plane.
Atom probe analysis of segregation in Fe–0.15 wt. % Ti
Authors: Pickering H. W. , Kuk Y. , Sakurai T.
Published: February 2003

A compositional analysis of a Fe-Ti alloy was carried out using a time-of-flight atom probe. It was found that titanium atoms are segregated to the surface and grain boundaries after heating to 1073 or 1273 K at 10−6 Pa (10−8 Torr). A decreasing titanium concentration profile extends over several atomic distances and even at 20 atomic distances from the surface the Ti concentration is above the nominal bulk value. In the outermost surface layers and in the grain boundaries titanium is present in the form of oxide, mainly TiO and TiO2, whereas in the subsurface atom-layer region it is present as randomly distributed titanium atoms and to a lesser degree as clusters of Ti around impurities, such as C, N, and O.
Ablative optical recording using organic dye-in-polymer films
Authors: Law K. Y. , Vincett P. S. , Loutfy R. O. , Alexandru L. , Hopper M. A. , Sharp J. H. , Johnson G. E.
Published: February 2003

Ablative optical recording using dissolved dyes in polymer films has been investigated. Polyester yellow dissolved in poly(vinyl acetate) was used as a model to study the potential for high-sensitivity, high-density optical storage applications. With 20% dye loading, a 59-nm film was more sensitive at 457 nm than a 15-nm Te monolayer, and marks down to 0.5 μm were recorded. The signal contrast (Rf−Ri)/(Rf+Ri) was approximately 0.68 for marks ablated with high-energy laser pulses. The morphology of the marks shows a clean removal of recording material. Suitable polymeric overcoatings, used to simulate second-surface recording situations, had little effect on the results.
Theoretical model of an optoacoustic detector
Authors: Gupta Jitendra P. , Sachdev Rajendra N.
Published: February 2003

It has been reported from experimental observations that a pressure pulse generated in a gas column by absorption of infrared radiation having a chopping frequency coincident with the natural resonant frequency of the gas column is independent of the chopping rate. A theoretical proof for this is given here by extending the theory of operational characteristics of a pneumatic detector derived earlier.
Analysis of the dark film in rf-excited mercury lamps
Authors: Heimann P. A. , Simpson J. H.
Published: February 2003

The dark film which forms in some rf-excited mercury discharge lamps has been characterized using several analytic techniques. This film is about one micron thick, and contains only mercury, silicon, oxygen, and possibly hydrogen. Several models for the physical and chemical nature of this film are presented and are compared with the experimental results. A mechanism for film growth is proposed.
An integrated photoconductive detector and waveguide structure
Authors: Gammel J. C. , Ballantyne J. M.
Published: February 2003

A new photoconductive detector is described that uses the previously reported optical field effect transistor structure. The detector has good sensitivity (photoconductive gain of ∼5) and high speed (∼150 psec). Light was coupled to this detector via a 7059 glass over SiO2 waveguide. The overall coupling efficiency including losses in endfire coupling was about 40%.
Measurements of the rectifying barrier heights of various rhodium silicides with n-silicon
Authors: de Sousa Pires J. , d’Heurle F. , Norde H. , Petersson S. , Tove P. A.
Published: February 2003

The barrier height of Schottky diodes formed with 〈111〉 and 〈100〉 n-type silicon substrates and Rh, RhSi, Rh4S5, and Rh3Si4 have been determined by means of photoresponse, capacitance, and forward current-voltage measurements. The results are compared to the results previously obtained with iridium, and with other plantinum related elements.
Laser irradiation of furnace preannealed (111) ion implanted silicon
Authors: Campisano S. U. , Foti G. , Servidori M.
Published: February 2003

The regrowth of self-ion implanted amorphous layer on (111) silicon substrate induced by laser pulse is shown to require less energy density in furnace preannealed sample. After 450 °C 30-min thermal treatment, the energy threshold is reduced about 30%. The extended defects near the threshold exhibit different geometrical arrangement.
Size effects in MoSi2-gate MOSFET’s
Authors: Chow T. P. , Steckl A. J.
Published: February 2003

Refractory metal silicide gate n-channel MOSFET’s have been fabricated by rf sputtering from a hot-pressed MoSi2 alloy target. The annealed MoSi2 sheet resistance was 2 Ω/⧠. The MOSFET’s were fabricated using plasma etching, projection alignment, and a fully ion-implanted process. Typical values for a 1.7×1.7-μm2 linear MOSFET are a threshold voltage of 1–1.5 V and a transconductance of 50–100 μmho. Short-channel (length and width) and substrate effects on the threshold voltage are demonstrated.
Transition with grain size from electrode-limited to bulk-limited conduction in polycrystalline semiconductors
Authors: Hwang W. , Card H. C. , Yang E. S.
Published: February 2003

An experimental study of Au-polycrystalline GaAs Schottky barriers has been made. The current-voltage and capacitance-voltage characteristics of GaAs films of various grain sizes have been measured. Analysis of these data indicate that the transport may be electrode-limited, bulk-limited, or a combination of electrode-limited and bulk-limited conduction processes, depending upon the (average) grain size.
Nonoverlapping dual-gate bucket-brigade devices
Authors: Barsan Radu M. , Delibaltov Adriana
Published: February 2003

A novel bucket-brigade charge-transfer device concept is presented and experimentally verified. The dual-gate BBD exhibits operational performances comparable to surface-channel charge-coupled devices, while still enjoying fabrication simplicity and high yield. The concept is implemented using conventional p-channel aluminum-gate technology with only an additional shadowed-gap lift-off process which produces self-aligned bias-gate electrodes separated from the adjacent clock buses by submicron (typically 0.5 μm) spacings. Transfer inefficiencies below 10−4 at 100 kHz and around 5×10−4 at 1 MHz have been currently observed, despite the low carrier mobility (140 cm2/V s).
Phase separation in alloy-Si interaction
Authors: Ottaviani G. , Tu K. N. , Mayer J. W. , Tsaur B. Y.
Published: February 2003

Phase separation has been found to be a general phenomenon among many alloy-Si interactions at temperatures as high as 800 °C. We have studied these interactions with alloys consisting of a near-noble metal of Ni, Pd, and Pt, and a refractory metal of Cr, V, and W. The interaction produces a silicide of the near-noble metals next to the Si and an outer layer of silicide of the refractory metals. No evidence for ternary formation has been found.
Lead alloy Josephson junctions with Pb-Bi counterelectrodes
Authors: Lahiri S. K. , Basavaiah S. , Kircher C. J.
Published: February 2003

An experimental investigation has indicated that the ε-phase Pb-Bi alloy is an attractive alternative to Pb–1.7 wt.% Au for use as a counterelectrode for Josephson tunneling devices containing Pb–12 wt.% In–4 wt.% Au alloy films as base electrodes and control lines. Use of this Pb-Bi alloy as a counterelectrode results in a significant improvement in junction quality; the normalized subgap single-particle tunneling current is ∼2× lower at 2 mV. In addition, devices with the Pb-Bi counterelectrodes exhibit ∼3× fewer failures after repeated thermal cycling between 300 and 4.2 °K. Out ot a total of 72 such devices having large area (6.2×10−6 cm2) junctions, 94% survived 1000 thermal cycles with negligible change.
On the long-term stability of CdxHg1−xTe at 300 K
Authors: Micklethwaite W. F. H. , Redden R. F.
Published: February 2003

Recently reported changes in the characteristics of bulk CdxHg1−xTe material stored open for periods of years at 300 K can be explained by the cross diffusion of Hg in the presence of interstitial-vacancy concentration gradients and/or surface exchange with the ambient. These mechanisms are thought to be inoperative in working photoconductive devices fabricated from such materials.
Optical bistable device as electro-optical multivibrator
Authors: Sohler W.
Published: February 2003

A truly bistable device using an integrated optical cutoff modulator in LiNbO3 is reported. With appropriate optical input power, the device may be used as an electrical Schmitt trigger (electrical bistability). By electrical feedback, electro-optical multivibrator operation is demonstrated.
High-output power InGaAsP (λ=1.3 μm) strip-buried heterostructure lasers
Authors: Nelson R. J. , Wright P. D. , Barnes P. A. , Brown R. L. , Cella T. , Sobers R. G.
Published: February 2003

An InGaAsP (λ=1.3 μm) strip-buried heterostructure laser with active layer strip widths of 5 μm is described. These devices show stable fundamental-transverse-mode operation with linear light-current characteristics to pulsed output powers over 100 mW. Output powers as high as 500 mW are observed without catastrophic damage, which corresponds to twice the power output at which catastrophic mirror damage occurs for similar GaAlAs SBH lasers. Far-field beam divergence is approximately 10° and 30° in the directions parallel and perpendicular to the junction, respectively. cw operation with a threshold current of 170 mA has been achieved at room temperature.
Minority carrier diffusion length measurements in CdTe by a photocurrent technique
Authors: Lastras-Martínez A. , Raccah P. M. , Triboulet R.
Published: February 2003

A simple technique for measuring the minority carrier diffusion length in semiconductors is demonstrated. The technique does not require the knowledge of any parameter of the investigated material. It consists, basically, in measuring the photocurrent of a semiconductor-electrolyte Schottky barrier, as a function of applied reverse bias. Weakly absorbed light is used, so that the light penetration depth is much larger than the Schottky barrier width. The diffusion length of n-type CdTe doped at a concentration of 8×1014/cm3 is found to be 1.75 μm.
Radiation-enhanced diffusion growth of Nb3Sn monofilaments: Grain-size effects on critical-current density
Authors: Snead C. L. , Suenaga M.
Published: February 2003

2-MeV electron irradiation of Nb cores in Cu-Sn bronze matrixes has produced A15 Nb3Sn layers for irradiation temperatures between 290 and 500 °C. Growth of layers at these temperatures (below those for which Nb3Sn is reacted thermally) results in critical-current densities that are higher than those of thermally produced specimens. Analysis of critical-current–vs–applied-field measurements shows that the increased critical-current density is consistent with smaller grain sizes in the lower-temperature enhanced diffusion grown Nb3Sn. Although this is due in part to reduced grain growth at lower temperatures, the possibility of radiation-enhanced grain nucleation is also considered. This is the first demonstration that enhanced diffusion can be used to grow a layer of material at the interface of two dissimilar metals, the new layer being an entirely different crystal structure from the constituents forming the interface.
Predicted conversion gain in superconductor-insulator-superconductor quasiparticle mixers
Authors: Tucker J. R.
Published: February 2003

A computer simulation is constructed to describe the performance of superconductor-insulator-superconductor (SIS) quasiparticle heterodyne receivers in terms of photon-assisted tunneling theory. The results predict that conversion efficiencies greater than unity can be realized at millimeter wave frequencies, with noise temperatures approaching the fundamental quantum limit. The nonlinearity responsible for the mixing is the extremely rapid onset of quasiparticle tunneling current in SIS junctions near the full gap voltage 2Δ/e, and is independent of the Josephson pair currents. Substantial gain is expected under a variety of conditions and for a wide range of source and load impedances.
Spectroscopic evidence of multiphoton absorption in nitrogen
Authors: Baravian G. , Godart J. , Sultan G.
Published: February 2003

Nitrogen pressure ∼2 Torr provides conditions which allow the spectroscopic study of the multiphoton absorption processes under the action of a neodymium glass laser radiation. From the laser flux dependence of the light intensity emitted by different excited states of nitrogen, we point out various absorption processes leading to the ionization and dissociation of the molecule and to the ionization of the atom.
Channeling of implanted phosphorus through polycrystalline silicon
Authors: Seidel T. E.
Published: February 2003

Implanted phosphorus was found to penetrate phosphorus-diffused polycrystalline silicon (polysilicon or poly) gate masks during complimentary metal oxide semiconductor processing. The result is unwanted depletion mode (turned-on) N-channel metal oxide semiconductor transistors. The effect is interpreted as channeling of phosphorus through large-grain polysilicon. The channeling effects were eliminated when (1) the upper polysilicon atomic layers were made amorphous prior to 31P+ implantation, (2) thermal oxides were grown to a thickness which prevents high-energy 31P+ from entering the grains of the polysilicon, or (3) when the ion-energy-to-poly thickness ratio is reduced below about 200 keV/μm.
Amorphous Si-F-H solar cells prepared by dc glow discharge
Authors: Konagai Makoto , Takahashi Kiyoshi
Published: February 2003

Amorphous Si-F-H films were prepared by dc glow discharge in an atmosphere of SiF4 + H2. Optical and electrical measurements have been performed to evaluate the film quality. The photoconductivity of amorphous Si-F-H solar cell showed the efficiency of 1.3% under simulated AM1, 100-mW/cm2 insulation.
Electron mobility in compensated GaAs and AlxGa1−xAs
Authors: Stringfellow G. B.
Published: February 2003

A term μCA in electron mobility proportional to T−1/2 is observed in highly compensated GaAs and AlxGa1−xAs. μCA has previously been thought to be due to space-charge scattering. Illumination with above-band-gap light is found to have no effect on μCA. Thus it could not be due to scattering from space-charge regions, which are collapsed by such illumination. μCA is found to be proportional to N−1A in nonintentionally doped specimens where C is the major shallow acceptor. For intentional compensation with Ge and Zn, no decrease in μCA is observed. μCA may be due to scattering from the local central-cell potential of the strongly electronegative C.
Power output enhancement of a laser-produced Cd plasma recombination laser by plasma confinement
Authors: Silfvast W. T. , Szeto L. H. , Wood O. R.
Published: February 2003

Enhancements of over a factor of 22 in power output and a factor of 130 in energy output of a laser-produced Cd plasma recombination laser have been achieved by using guides to confine and elongate the plasma and control its cooling. Such techniques may prove useful in increasing the efficiency of recombination lasers and also in enhancing the prospects of scaling these devices to shorter wavelengths.
Surface vacancies in InP and GaAlAs
Authors: Daw Murray S. , Smith D. L.
Published: February 2003

We present calculations of the bound-state energy levels of ideal vacancies near the (110) surface of InP and GaAlAs. We find that there is a strong correlation between the the calculated position of the highest filled anion vacancy level in the neutral vacancy and the measured Fermi level at the surface. This correlation suggests that the recently proposed defect model of Schottky barrier formation is capable of accounting for the observed trends in Schottky barrier formation and that the states responsible in III-V semiconductors are related to defects which introduce dangling cation bonds.
Classical absorption and heat conduction in low-irradiance, long-pulse CO2-laser-plasma interactions
Authors: Montes A. , Hubbard M. , Kler C. , Spalding I. J.
Published: February 2003

A self-regulating model of classical collisional absorption and heat conduction is shown to adequately explain cold-electron temperatures measured in low-irradiance, long-pulse CO2-laser-plasma experiments at Culham. The absorption predicted by the model is a large fraction of the very high experimentally measured absorption and the predicted density scale length agrees very well with the experimental value.
Deep-level changes in (Al,Ga)As double-heterostructure lasers degraded during accelerated aging at high temperatures
Authors: Uji T. , Suzuki T. , Kamejima T.
Published: February 2003

Deep levels in (Al,Ga)As double-heterostructure lasers have been studied by deep-level transient spectroscopy during accelerated aging at junction temperatures in the 120–320 °C range. A marked correlation has been found between the concentration increase of a hole trap and the threshold increase in degraded lasers. This hole trap is at 0.24 eV from the valence band in the n-AlGaAs passive layer. Capture cross section of this level at 145 K was 2×10−19 cm2 for electron capture and ≳5×10−15 cm2 for hole capture. The 0.24-eV-trap increasing rate was accelerated with an activation energy of 0.54±0.07 eV as the aging temperature was raised. The 0.24-eV trap seems to be closely related to the ’’slow long-term degradation’’ in (Al,Ga)As lasers and LED’s, which limits the lifetime of these devices to 105–106 h at room temperature.
Hysteresis and optical bistability in degenerate four-wave mixing
Authors: Winful Herbert G. , Marburger John H.
Published: February 2003

The intensity-dependent refractive index leads to hysteresis and optical bistability in degenerate four-wave mixing processes (DFWM). Bistability may be observed in the phase conjugate signal or in the ’’spontaneous’’ oscillation possible in DFWM. This bistability does not require external resonant cavities.
Control of XeF laser output by pulse injecton
Authors: Pacala Thomas J. , Christensen C. P.
Published: February 2003

Injection locking is investigated as a means for control of optical pulse duration and polarization in a XeF laser. Intense short-pulse generation in the ultraviolet is achieved by injection of a low-level 1-ns optical pulse into a XeF oscillator. Control of laser output polarization by injection locking is demonstrated and studied as a function of injected signal level. Enhancement of XeF electric-discharge laser efficiency by injection pulse ’’priming’’ is observed.
Method for measuring the rf modulation characteristics of Mach-Zehnder-type modulators
Authors: Auracher F. , Keil R.
Published: February 2003

We derive the frequency spectrum of the light output from Mach-Zehnder-type waveguide modulators and demonstrate the excellent agreement of the experimental results with theory. From the measurement of the frequency spectrum the rf modulation characteristics can be deduced. This method is advantageous as it permits the evaluation of the modulator performance up to frequencies above 1 GHz without requiring high optical power, thus eliminating the risk of optical damage in the waveguides. The tested modulator shows a 3-dB cutoff frequency of 1.1 GHz; the figure of merit is Q≈130 μW/MHz.
Compositional inhomogeneity of liquid phase epitaxial InGaPAs layers observed directly in photoluminescence
Authors: Rezek E. A. , Vojak B. A. , Chin R. , Holonyak N.
Published: February 2003

Data are presented on photopumped rectangular samples indicating that immediately (⩽18 ms) after the LPE growth of In1−xGaxP1−zAsz on InP begins a thin ∼100-Å quaternary layer is deposited of lower energy gap (ΔE∼15 meV) than that of the succeeding LPE thicker layer that grows later near diffusion-limited quasiequilibrium conditions. This conclusion is based on a comparison made between the photoluminescence spectra from a single quaternary layer deposited in ∼1 s of uninterrupted growth and that from a composite InGaPAs layer consisting of nine successive depositions of the initial thin layer.
Anomalous sputter yields due to cascade mixing
Authors: Williams Peter
Published: February 2003

Sputter-removal rates of overlayer and interfacial species on silicon are analyzed to determine sputtering yields for the species involved. Sputtering yields up to two orders of magnitude lower than those measured for silicon are found, and the results are interpreted in terms of a cascade mixing process which continually reburies much of the overlayer material beyond the escape depth of the sputtered atoms.
Distributed-feedback dye laser integrated with a channel waveguide formed on silicon
Authors: Sriram S. , Jackson Howard E. , Boyd J. T.
Published: February 2003

Successful operation of an integrated optical distributed-feedback (DFB) dye laser in which generated light is confined in a V-groove optical channel waveguide is reported. Both the channel waveguide and second-order diffraction grating for DFB operation are formed by anisotropic-etching the silicon substrate. Polyurethane doped with rhodamine 110 dye is used for the laser waveguide region, while undoped polyurethane is used for channel waveguides. Use of an argon laser for pumping yields continuous output at λ=6430 Å characterized by a very low threshold and a spectral width less than 2 Å. The output wavelength is consistent with the grating period of 4150 Å.
New bistable cholesteric liquid-crystal display
Authors: Berreman D. W. , Heffner W. R.
Published: February 2003

We have made a new type of cholesteric liquid-crystal display device that is bistable in the absence of an applied field. One of the two stable states has 360° of twist between the two surfaces. The other is an untwisted state, like an unstrained nematic with all directors parallel. One method of switching is to apply a pulse of about 3 V or more between the cell surfaces, to obtain the twisted state or a pulse of about 1.5–2 V to obtain the untwisted state. Lesser pulses have no lasting effect. These switching characteristics have promise for displays with large numbers of characters.
Degenerate four-wave mixing of 10.6-μm radiation in Hg1−xCdxTe
Authors: Jain R. K. , Steel D. G.
Published: February 2003

We report observation of a large nonlinear optical susceptibility in HgCeTe for degenerate four-wave mixing of 10.6-μm radiation. Using pump pulses of 180 ns duration and 160 kW/cm2 peak intensity, nonlinear reflection coefficients of oiver 10% have been observed. The experimentally measured value of χ(3) is approximately 5.4×10−6 esu, in reasonable agreement with calculations based on a Drude model for the optically generated plasma. We have also observed nonlinear Fabry Perot effects in our samples.
Pulse acousto-optic modulator using a nematic liquid crystal in its isotropic phase
Authors: Martinoty P. , Bader M.
Published: February 2003

A simple and sensitive pulse acousto-optic modulator using a nematic liquid crystal in its isotropic phase is presented. The effects of acoustic intensity and of temperature are considered. It is shown that modulation can be obtained at very low values of the applied voltage.
Real-time image processing via four-wave mixing in a photorefractive medium
Authors: White Jeffrey O. , Yariv Amnon
Published: February 2003

We report the application of four-wave mixing to real-time image processing. We constructed a nonlinear optical processor using a photorefractive medium Bi12SiO20 and demonstrated that it is capable of convolving and correlating objects with spatial information.
Prevention of InP surface decomposition in liquid phase epitaxial growth
Authors: Antypas G. A.
Published: February 2003

Decomposition of InP prior to and following liquid phase epitaxial growth can be completely eliminated by locally providing an increase in P partial pressure compared to that at the InP liquidus. The increase of P partial pressure is a result of increased P solubility in In-Sn-P solutions.
Transition to faceting in multilayer liquid phase epitaxy of GaAs
Authors: Scheel Hans J.
Published: February 2003

During deposition of p- and n-GaAs multilayers by a novel liquid phase epitaxy (LPE) technique on slightly misoriented substrates, a gradual transition from macroscopically steped surfaces to faceting has been observed. The change from various different growth mechanisms on corrugated LPE-grown surfaces to a single one with propagating steps of heights of the order of 10 Å leads to extremely flat surfaces and to improved homogeneous dopant incorporation. These factors are likely to increase the performance of optoelectronic and microwave devices.
Hysteresis and memory properties of platinum-diffused metal-oxide-silicon structures
Authors: Nassibian A. G. , Faraone L.
Published: February 2003

Experimental results of hysteresis effects observed on platinum-diffused 〈111〉 metal-oxide-silicon structures are presented. The experimental observations point to this phenomenon being associated with some bias-dependent charge storage at the oxide-silicon interface or mobile platinum ions in the oxide. This platinum-induced hysteresis exhibits memory properties owing to its nonvolatile nature.
High-energy implantation of silicon in GaAs
Authors: Liu S. G. , Douglas E. C. , Magee C. W. , Kolondra F. , Jain S.
Published: February 2003

The impurity profiles and electrical properties of 28Si+-implanted GaAs at energies up to 1.2 MeV have been studied. Mobility of up to ∼4000 cm2/V s and activation efficiency of ∼75% have been measured in 1-MeV-implanted capless-annealed GaAs samples. Multiple implants have been used in producing a ∼1-μm-deep uniformly doped n layer.
Real-time x-ray topography studies of the viscoelastic behavior of SiO2 in the system Si/SiO2
Authors: Hartmann W. , Franz G.
Published: February 2003

The viscoelastic behavior of SiO2 in the system Si/SiO2 during isothermal heat treatment is studied by directly imaging the x-ray topography contrast due to lattice strains at oxide edges of test structures. We measure the relaxation time of those strains, e.g., the time to reach zero x-ray contrast, at different temperatures above 900 °C, the minimum temperature for plastic deformation of SiO2. An Arrhenius plot of the relaxation time yields activation energies for viscous flow of 4.3 for normal- and 2.3 eV for high-pressure thermal SiO2. For small rectangular oxide windows we find the relaxation time proportional to the square root of the window area.
Comparison of solar cell performance to calculations using different energy band-gap narrowing models
Authors: Weaver H. T.
Published: February 2003

Three different energy band-gap narrowing models were used for exact numerical calculations of silicon solar cell performance. The results are compared to data from high-efficiency cells. Two of the gap narrowing models are derived empirically from other types of devices, and the third is theoretical. The applicability of the models to these cells is demonstrated.
Surface acoustic wave planar prism waveguide coupler
Authors: Davis K. L. , Weller J. F.
Published: February 2003

The design and experimental measurements of a planar prism waveguide coupler on YZ lithium niobate are presented. The coupler was used to compress a 60-wavelength-aperture surface acoustic wave into a 3-wavelength-wide Δv/v waveguide. The coupling efficiency was measured to be within 1 dB of the theoretical maximum 80% at the center frequency of 300 MHz. A 1.5-dB coupling bandwidth of 45 MHz was observed.
Surface and thickness effects in the luminescence of amorphous Si:H
Authors: Rehm W. , Fischer R. , Beichler J.
Published: February 2003

The luminescence decay of a-Si:H films is found to be strongly dependent on the sample thickness and on the penetration depth of the exciting light: the decay becomes faster for excitation close to the surface, and when the sample thickness is reduced. We suggest that these effects are due to surface electric fields.
Annealing of damage and redistribution of Cr in boron-implanted Si3N4-capped GaAs
Authors: Magee T. J. , Lee K. S. , Ormond R. , Blattner R. J. , Evans C. A.
Published: February 2003

Transmission electron microscopy and secondary-ion mass spectrometry have been used to determine the relative roles of encapsulant stress and implantation damage in the thermal redistribution of chromium. At low temperatures (500 °C), there is a plantation damage, while the encapsulant stress becomes predominant at higher temperatures.
Multifrequency x-ray backlighting of laser-imploded targets
Authors: Azechi Hiroshi , Oda Shigetoh , Hamano Michiko , Sasaki Takatomo , Yamanaka Tatsuhiko , Yamanaka Chiyoe
Published: February 2003

The compression of a 3.5-atm-neon-filled glass microballoon was recorded by time-resolved multifrequency x-ray backlighting with a gallium x-ray source which covers a suitable frequency region. A product of compressed density and radius ρR of (1.5–3.5)×10−4 g cm−2 and core temperature of greater than 200 eV were estimated from the spectral absorption characteristics.
Heteroepitaxy of Ge1−xSix on Si by transient heating of Ge-coated Si substrates
Authors: Fan John C. C. , Gale Ronald P. , Davis Frances M. , Foley George H.
Published: February 2003

Heteroepitaxial films of Ge1−xSix alloys have been obtained by transient heating of Ge-coated Si single-crystal substrates with a graphite strip heater. Structural characterization shows the films to be of good epitaxial quality. As the maximum temperature during heating is increased, the Ge content and the microtwin density of the films decrease.
High mobilities in AlxGa1−xAs-GaAs heterojuntions
Authors: Witkowski L. C. , Drummond T. J. , Stanchak C. M. , Morkoç H.
Published: February 2003

Electron mobilities as high as 6485 cm2/V sec at 300 and 57 260 cm2/V sec at 78 K were obtained in Al0.33Ga0.67As-GaAs modulation-doped single-period heterojunctions with an average electron concentration of ∼1017 cm−3. The achievement of such high mobility is the result of leaving part of the AlGaAs near the interface undoped. By varying the thickness of this undoped region, electron mobilities much greater than for uniformly doped AlGaAs in modulation-doped structures have been achieved. The electron mobility enhancement has been observed to increase with the increase of the undoped region, reach a maximum, and then decrease. Mobility enhancement was still observed up to the point of leaving a 200-Å undoped region in the AlGaAs. The peak mobilities for an AlAs mole fraction of 33% has been found to occur for an undoped region of 50 Å while for 25% the mobility peaks for 100 Å. The Al0.25Ga0.75As-GaAs modulation-doped structure had a slightly lower peak mobility, namely 50 234 cm2/V sec at 78 K. These results indicate a mobility improvement of about a factor of 2 over previously reported modulation-doped AlGaAs-GaAs structures at 78 K.
Effect of flow velocity on the photon statistics of a cw dye laser
Authors: Short R. , Roy Rajarshi , Mandel L.
Published: February 2003

The effect of changing the velocity of dye flow on the behavior of a cw dye laser is investigated by photon counting measurements. The results strongly suggest that changing the velocity over the range 10–13 m/sec merely changes the pump parameter, but leaves the other laser characteristics essentially unaltered. The average light intensity is found to be a linear function of flow velocity.
Structure of a laminar flame-wall interface by laser Raman spectroscopy
Authors: Bechtel J. H. , Blint R. J.
Published: February 2003

Temperature and species concentration measurements obtained by laser Raman spectroscopy are reported for a steady-state, laminar, methane-air flame impinging on a cooled metal wall. The concentration profiles for CH4, CO, and CO2 measured parallel to the wall at distances of 1500 (free flame) and 150 μm (near wall) are unexpectedly similar. This result is surprising in view of the much lower maximum temperature (870±50 K) measured at the near-wall location compared with the free flame (2000±50 K). Rapid fuel oxidation would not be expected at such low temperatures.
Two-photon pumped cw laser
Authors: Willenberg G. D. , Weiss C. O. , Jones H.
Published: February 2003

Infrared-microwave pumping of two-photon transitions in NH3 has led to cw laser emission of a number of NH3 transitions in the far infrared.
An electrochemical transistor using a solid electrolyte
Authors: Hetrick Robert E. , Vassell W. C.
Published: February 2003

Transistor action has been observed at elevated temperatures (800 °C) with a structure composed of two ceramic ZrO2 electrochemical cells separated by an enclosed volume. One cell emits O2 from an ambient atmosphere into the volume (base region) where it is collected and returned to the ambient by the opposing cell. Electrical operation can be understood in terms of the current limitation presented by the Pt cathode of the collector cell. Small signal voltage, current, and power amplification are observed with a frequency response limited by the double-layer capacity of the collector. This approach to transistor action should be applicable to other solid-electrolyte systems.
Oxygen striation and thermally induced microdefects in Czochralski-grown silicon crystals
Authors: Ohsawa A. , Honda K. , Ohkawa S. , Shinohara K.
Published: February 2003

Oxygen striations in Czochralski-grown silicon crystals have been directly observed by applying the scanning IR absorption technique to longitudinal sections. The oxygen striations were found to correlate clearly with thermally-induced-microdefect distributions. The results show that oxygen plays a very important role in microdefect formation. A critical oxygen concentration for microdefect introduction was estimated to be (7–8)×1017 cm−3 for 96-h, 600 °C heat treatment.
Reproducible diffusion of beryllium into GaAs during liquid phase epitaxial growth
Authors: Masu Kazuya , Konagai Makoto , Takahashi Kiyoshi
Published: February 2003

The diffusion of beryllium into GaAs during liquid phase epitaxial growth of beryllium-doped p-Ga0.2Al0.8As is investigated. The diffusion coefficient D takes the form D=D0 exp(−E0/kT), where D0=11.2 cm2 sec−1 and E0=2.43 eV.
Photoluminescence study of perturbed growth of InP on quaternary layers in InGaAsP-InP double heterostructures
Authors: Rao E. V. K. , Quillec M. , Benchimol J.-L. , Thibierge H.
Published: February 2003

Photoluminescence (PL) spectra of InGaAsP-InP laser double heterostructures show evidence for perturbed growth in the top InP confinement layers. The PL spectra of these layers are found to be a bnormally wide and exhibit two emission features hitherto unobserved in single InP epilayers. This perturbed growth of InP layers is attributed to a partial dissolution of the quaternary material by the In-P liquid where the dissolution process is favored by the compositional fluctuation in the growth plane of the InGaAsP active layers.
Direct observation of epitaxial islands of Pd2Si on (001) Si
Authors: Vaidya S. , Murarka S. P.
Published: February 2003

The formation of epitaxial islands of Pd2Si is reported on (001) Si. These islands are several microns in dimension and distributed heterogeneously in a fine-grained layer of the same phase. Crystallographic analysis suggests that they nucleate on {111} Si and then grow parallel to the substrate surface.
Beam nonuniformity effects on laser ablatively accelerated targets
Authors: Obenschain S. P. , Lehmberg R. H. , Ripin B. H.
Published: February 2003

We present results of a laser Doppler-shift technique which gives the velocity profiles of ablatively accelerated targets. Measurements of the effects of laser beam nonuniformity on the target acceleration are presented and interpreted in the context of laser pellet fusion.
An improved anodic oxide insulator for InP metal-insulated-semiconductor field-effect transistors
Authors: Laughlin D. H. , Wilmsen C. W.
Published: February 2003

Highly insulation oxide layers have been anodically grown on InP. The oxide was grown in an electrolyte of pH<2.5 which causes In203 to dissolve out of the growing oxide layer, resulting in a P2O5/In2O3 ratio larger than one. The increase in oxide resistivity is attributed to the high concentration of P2O5 in the layers, since the P2O5 has a large band gap.
Luminescence in slipped and dislocation-free laser-annealed silicon
Authors: Uebbing R. H. , Wagner P. , Baumgart H. , Queisser H. J.
Published: February 2003

Photoluminescence of cw laser-annealed silicon shows a dramatic difference in electronic behavior of the reconstructed material depending upon either creation or suppression of dislocations. Beyond a critical exposure time slip appears, and the luminescence of these samples is dominated by dislocation-related defect levels.
Iron doping in gallium arsenide by molecular beam epitaxy
Authors: Covington D. W. , Comas J. , Yu P. W.
Published: February 2003

Iron-doped GaAs layers have been grown by molecular beam epitaxy (MBE) over a substrate temperature range of 460–540 °C with incident 56Fe levels of 2×108–2×1011 atoms cm−2 sec−1. Photoluminescence studies indicate that iron can be incorporated on Ga sites in MBE GaAs. A pronounced accumulation of Fe at the outer epi-layer surface is observed in secondary-ion mass spectroscopy profiles of heavily doped samples. This accumulation leads to appreciable donor compensation in n-type GaAs subsequently grown.
Molecular beam epitaxial GaAs heteroface solar cell grown on Ge
Authors: Miller D. L. , Harris J. S.
Published: February 2003

GaAs/AlGaAs heteroface solar cells having AM1 efficiencies up to 17% have been grown by molecular beam epitaxy (MBE) directly on Ge (100) substrates. These cells on Ge have efficiencies identical to cells grown simultaneously on GaAs. The cells reported here are the highest efficiency MBE solar cells reported to date, and are the first high-efficiency GaAs solar cells grown directly on Ge by MBE.
Variable range hopping conductivity in reduced lead glass
Authors: Sandoe J. N. , Blood P. , Nicholls D. H.
Published: February 2003

We have measured the conductivity of a sample of reduced channel-plate lead glass over the temperature range 25–300 K. The behavior is consistent with conduction by two-dimensional variable range hopping. From measurements of the thickness of the conducting layer we estimate the wave-function overlap parameter α−1⩾50 Å and hence from the temperature dependence of the conduction we deduce that the density of states at the Fermi level is less than 4×1017 eV−1 cm−3.
Near-field and beam-waist position of the semiconductor laser with a channeled-substrate planar structure
Authors: Chen Chung-Yih , Wang Shyh
Published: February 2003

We demonstrated astigmatism in the output beam from the double-current-confinement channeled-substrate planar laser. A gradual transition from gain guiding toward index guiding is observed as the thickness of the cladding layer t is reduced. The near field is stable, and both the beam width and the beam-waist position are independent of the pumping levels over the range of current tested (up to 3 Ith).
New high-resolution charge transfer x-ray and electron beam negative resist
Authors: Hofer Donald C. , Kaufman Frank B. , Kramer Steven R. , Aviram Ari
Published: February 2003

A new class of polymeric negative x-ray and electron beam resists is described. Polystyrene-tetrathiafulvalene films doped with a halocarbon acceptor show good sensitivity to x-rays (D1/2=44 mJ/cm2) and electron beams (D1/2=6 μC/cm2), with high contrast values γ≳2.5, and with no evidence for the classical swelling phenomena. In electron beam exposures at 10 μC/cm2, parallel wall patterns are produced with pattern resolution of 1000 Å or better. Reasons for the improvement in lithographic parameters relative to previous negative resists are briefly discussed.
Cryogenic inertial confinement fusion target fabrication system directly operable inside a room-temperature target chamber
Authors: Kim K. , Rieger H.
Published: February 2003

An inertial confinement fusion (ICF) target freezing system, which is capable of fabricating a uniform layer of DT condensate inside a glass microshell, has been developed using cold helium gas jets. The system marks a significant improvement on the existing target freezing systems for the following reasons: first, it does not require cryogenic shields; second, it is directly operable inside a room-temperature target chamber; third, it maintains the integrity of a cryogenic target for as long as desired; fourth, since a bare target can be directly positioned inside the target chamber with no enclosure, implosion of the target using energetic beams (e.g., laser) can easily be achieved at any instant. Description of the system and some results illustrating its performance are presented along with their future applications.
Laser action in chromium vapor
Authors: Jain Kanti
Published: February 2003

A chromium-vapor laser is demonstrated using excitation in a hollow-cathode discharge. Oscillation is achieved at eight wavelengths in the near-infrared, with a multiline quasi-cw output power of 20 mw. Two of the transitions are attributed to Cr I and one to Cr II, the remaining five being unidentified. This, it is believed, is the first report of stimulated emission in neutral as well as singly-ionized chromium.
Investigation of rf sputter-etched Si surface by spectroscopic ellipsometry
Authors: Ohira F. , Itakura M.
Published: February 2003

Spectroscopic ellipsometry is applied to estimate the crystal damage to a rf sputter-etched Si surface. The single-crystal surface examined by this method has a sharp peak which corresponds to the intrinsic peak in Si. The spectrum change in the refractive index for a Si surface processed by rf sputter etching is measured and discussed. It is found experimentally that the increase in the k value, the imaginary part of the refractive index, at 5461 Å is the result of broadening of the k spectrum due to crystal damage, and that the characterization of the Si surface by ellipsometry at wavelengths of 4200–4500 Å is effective and reasonable.
Capacitance-voltage characteristics of Al/Al2O3/p-GaAs metal-oxide-semiconductor diodes
Authors: Hayashi H. , Kikuchi K. , Yamaguchi T.
Published: February 2003

Metal-oxide-semiconductor (MOS) diodes were constructed on p-type GaAs by means of anodic oxidation of aluminum film evaporated on GaAs. By terminating the oxidation precisely at the Al-GaAs interface, MOS diodes in which the capacitance at low frequency increases in the positive-bias region were obtained. The interface state density determined by using the Terman method based on 1-MHz measurement of the C-V characteristics is on the order of 1010 cm−2 eV−1.
The effects of cold rolling on fluxoid pinning in a superconducting metallic glass
Authors: Koch C. C. , Scarbrough J. O. , Kroeger D. M. , DasGupta A.
Published: February 2003

Results exhibiting the influence of cold rolling fluxoid pinning in a metalic glass superconductor (Mo0.6Ru0.4)82B18 are reported. Inhomogeneous deformation up to 20% reduction in thickness does not change either the superconducting transition temperature Tc or upper critical field Hc2 but does degrade the critical current density by as much as 34% from the value in the the as-cast condition. Possible mechanisms for this degradation of Jc are suggested. Pinning by inhomogeneities in composition or density rather than by the simple surface or unresolved second-phase precipitates appears to be likely.
Silicon graphoepitaxy using a strip-heater oven
Authors: Geis M. W. , Antoniadis D. A. , Silversmith D. J. , Mountain R. W. , Smith Henry I.
Published: February 2003

Silicon graphoepitaxy has been achieved using a strip-heater oven and a sample configuration consisting of a relief grating in a SiO2 substrate, a deposited amorphous silicon film, and a deposited SiO2 overlayer or ’’cap.’’ The resulting films are free of cracks and superior in crystallographic orientation and surface smoothness to graphoepitaxial films produced by laser crystallization. Enhancement-mode, n-channel, insulated polysilicon gate field-effect transistors were fabricated and gave surface mobilities of 400 cm2/V sec at a p doping of 1016 cm−3. A SiO2 cap, either intentionally deposited or produced by laser crystallization in the presence of oxygen, was found to be necessary for Si graphoepitaxy. We attribute this effect to shear stresses produced by the SiO2 cap during crystallization.
Accessibility of the KrF*(B) state to laser photons
Authors: Jacob J. H. , Trainor Daniel W. , Rokni M. , Hsia J. C.
Published: February 2003

Using electron beam excitation of Ar/Kr/F2 mixtures in a 1-m laser, we monitored KrF*(B) sidelight fluorescence of the 249-nm B→X transition. Comparing signals observed in the presence and absence of cavity flux, we evaluated the ability of the photon field to depopulate the upper laser level by stimulated emission. From these experiments, we concluded that some of the KrF* population was in higher vibrational levels and could not be effectively extracted by stimulated emission at the normal laser operating wavelength.