bluuebunny/crossref_metadata_2025 huggingface dataset:
Absorption in the triatomic excimer, Xe2Cl
Authors: Stevens W. J. , Krauss M.
Published: February 2003

The equilibrium internuclear geometry has been calculated for the excimer state of Xe2Cl. At this geometry absorption and emission transition probabilities have been calculated for transitions that bear on the gain of the Xe2Cl excimer transition and of the XeCl C–A transition. The total lifetime of the Xe2Cl excimer state is found to be 330 ns for a fluorescence peak at 495 nm. Significant absorption is found to peak at 438 nm which would preclude tuning a laser over the entire fluorescence band. A very strong absorption from the Xe2Cl excimer state is also found at 339 nm which practically coincides with the broadband XeCl C–A transition.
High-power, single-mode operation of an InGaAsP/InP laser with a grooved transverse junction using gain stabilization
Authors: Chen T. R. , Koren U. , Yu K. L. , Lau K. Y. , Chiu L. C. , Hasson A. , Margalit S. , Yariv A.
Published: February 2003

The high-power performance of a groove InGaAsP/InP transverse junction laser fabricated on a semi-insulating InP substrate has been investigated. Peak power of over 250 mW/facet for pulsed operation and 11 mW/facet cw are achieved with stable fundamental mode operation and narrow beam width. It is suggested that the single-mode operation is caused by a gain stabilizing mechanism related to the transverse junction injection profiles.
Fiber-optical sensor for surface acoustic waves
Authors: Bowers J. E.
Published: February 2003

A new sensor is presented for detecting surface acoustic waves (SAW). The probe is constructed using single-mode fiber components (two directional couplers, a polarization controller, and a phase modulator) with a laser diode and detector. This sensor has the advantages of being small and rugged and does not require an optical bench for stability. The sensor can detect acoustic waves over a dynamic range of 110 dB and has better amplitude sensitivity (0.0003 Å) than has been reported for other SAW sensors.
Comparison of guided wave approaches to optical bistability
Authors: Stegeman George I.
Published: February 2003

The minimum power required for a nonlinear phase shift of π/2, and the maximum propagation distance are evaluated for the semiconductors GaAs and InSb in four guided wave geometries: surface plasmons at the interface between two semi-infinite media and guided by a thin metal film, and single and multilayer thin-film optical waveguides. Optimum configurations compatible with guided wave technology are identified.
Room-temperature excitonic optical bistability in a GaAs-GaAlAs superlattice étalon
Authors: Gibbs H. M. , Tarng S. S. , Jewell J. L. , Weinberger D. A. , Tai K. , Gossard A. C. , McCall S. L. , Passner A. , Wiegmann W.
Published: February 2003

The quantum wells provided by a superlattice increase the binding energy of the free excitons in GaAs, permitting 300 K bistable operation of a superlattice etalon. The superlattice consists of 61 periods of 336 Å GaAs and 401 Å Ga0.73Al0.27As. The intensities required are about 1 mW/ ( μm)2 and the switching times are 20–40 ns, similar to the low-temperature pure GaAs values. Room-temperature operation of semiconductor etalons enhances the likelihood of all-optical logic and switching.
CdxHg1−xTe n-type layers grown by molecular beam epitaxy
Authors: Faurie J. P. , Million A.
Published: February 2003

CdxHg1−xTe n-type layers have been grown by molecular beam epitaxy (MBE) on CdTe (111) orientation substrates at growth temperatures between 120 and 180 °C. It is shown, as predicted previously for films grown at 110 °C, that an improvement in structural quality by a substrate temperature raise and growth in a Hg flux is followed by an improvement of electrical properties. For substrate temperature Ts = 180 °C films have low carrier concentration and high electron Hall mobilities close to the best value reported for layers grown by other techniques. These results indicate that MBE is now a promising technique for CdxHg1−xTe device applications.
Manifestations of melt-carry-over in InP and InGaAsP layers grown by liquid phase epitaxy
Authors: Mahajan S. , Brasen D. , DiGiuseppe M. A. , Keramidas V. G. , Temkin H. , Zipfel C. L. , Bonner W. A. , Schwartz G. P.
Published: February 2003

Macroscopic evidence for the occurrence of melt-carry-over (MCO) in InP and InGaAsP layers, grown by liquid phase epitaxy, is presented. It is shown that MCO can manifest itself in the form of dissolution pits and holes in epilayers. Further, this carry-over can occur in any stage of epi growth and can propagate through subsequent epitaxial layers. Thus, holes transcending all four layers constituting a device wafer can form if wipe-off after an In-melt back is incomplete, and these holes have deleterious effects on device yield.
X-ray photoelectron spectroscopic studies of oxygen chemisorption on thick films of photoconducting cadmium sulfide
Authors: Amalnerkar D. P. , Badrinarayanan S. , Date S. K. , Sinha A. P. B.
Published: February 2003

X-ray photoelectron spectroscopic studies of highly photosensitive thick films of cadmium sulphide have been carried out which reveal the appearance of a complex triplet structure (S2p) spread over about 20 eV with peaks centered at binding energy values of 162.6, 172.8, and 179.7 eV. Using the available literature data, the S2p peak at 162.6 eV is interpreted to originate from S−− ions, the one at 172.8 eV from the SO−−4- like species and that at 179.7 eV from SO2-like species, the latter two being formed on the surface due to the preferential bonding of chemisorbed oxygen with sulphur. After thermal desorption, the films exhibit no photosensitivity and there is a substantial reduction in the intensities of 172.8- and 179.7-eV peaks. A close link between the existence of SO−−4 and SO2 (adsorbed) species and photoconductivity is clearly manifested.
Imaging of domains and grain boundaries in a ferroelectric semiconducting ceramic
Authors: Ralph J. E. , Gowers J. P. , Burgess M. R.
Published: February 2003

This letter describes experiments using the scanning electron microscope in the electron beam induced current mode to image ferroelectric domains and grain boundaries in a positive temperature coefficient ceramic. The mechanism responsible for the observed contrast is discussed together with the relevance of the observations to a previously published hypothesis concerning the interaction between domains and grain boundary barriers.
Barrier height of Au on n-GaAs1−xSbx diodes
Authors: Subramanian S. , Murawala P. A. , Chandvankar S. S. , Arora B. M.
Published: February 2003

The barrier height of Au-n-GaAs1-xSbx Schottky diodes was measured in the range of Sb compositions 0⩽x<0.2. As x increases from 0 to 0.1, the barrier height decreases by about the same amount as the decrease in the band-gap energy. For x≳0.1, the decrease in barrier height is less in comparison with the decrease of band gap. This behavior can be related to the ’’defect model’’ of the barrier formation.
Offset channel insulated gate field-effect transistors
Authors: Chen C. Y. , Cho A. Y. , Gossard A. C. , Garbinski P. A.
Published: February 2003

We report a new insulated gate field-effect transistor, which has a conducting channel created by the band bending and band edge discontinuity at a selectively doped Al0.3Ga0.7As/GaAs interface rather than at the insulator-semiconductor interface. The device can be operated both in the depletion mode and in the enhancement mode with a dc transconductance of 18 mmho/mm in both cases (gate length = 5.2 μm). The gate electrode can sustain a positive voltage greater than 2 V. Preliminary results indicate that the idea of offset channel can be of great importance for realizing ultrahigh speed transistors.
Combined microcrystal and amorphous silicon cells
Authors: Fang P. H. , Schubert C. C. , Bei Peiguang , Kinnier J. H.
Published: February 2003

Solar cells have been constructed by depositing a microcrystalline p-silicon layer on an amorphous i-n structure. Here p and n denote the type of dopant and i the intrinsic. The silicon layers are formed by electron beam evaporation and doped through the coevaporation of boron for p type and antimony for n type. After hydrogenation by plasma annealing, solar cells are obtained with an open circuit voltage of 540 mV and short circuit current of 5 mA/cm2 under AMl simulated light. The fill factor is 46%.
Terraced-heterostructure large-optical-cavity AlGaAs diode laser: A new type of high-power cw single-mode device
Authors: Botez D. , Connolly J. C.
Published: February 2003

A new terraced lateral wave confining structure is obtained by liquid phase epitaxy over channeled substrates misoriented perpendicular to the channels’ direction. Single spatial and longitudinal mode cw operation is achieved to 50 mW from one facet, in large spot sizes (2×7.5 μm, 1/e2 points in intensity) and narrow beams (6°×23°, full width half-power). At 70 °C ambient temperature cw lasing is obtained to 15 mW from one facet. Weak mode confinement in an asymmetric lateral waveguide provides discrimination against high-order mode oscillation.
Schottky diode mixer for visible laser light and microwave harmonics up to 0.43 THz
Authors: Daniel H.-U. , Maurer B. , Steiner M. , Walther H.
Published: February 2003

An open-structure W-GaAs Schottky point-contact diode was tested as an efficient mixer device for visible laser light and microwave radiation. Beat signals between the lines of a krypton ion laser at 568 nm, and of a dye ring laser and the emission of a backward wave oscillator at 85.4 GHz, showed signal-to-noise ratios of 50 dB. Microwave harmonics generated in the same diode could be mixed with the two laser lines up to frequency differences of 430 GHz (i.e., 5th harmonic). A comparison with other mixers for the visible spectral range is given.
Stress-induced frequency tuning for stimulated four-photon mixing in a birefringent single-mode fiber
Authors: Kitayama Ken-ichi , Seikai Shigeyuki , Uchida Naoya
Published: February 2003

In stimulated four-photon mixing using a stress-induced birefringent fiber, the frequency shift of the stimulated emission has been tuned by changing the modal birefringence with an external force applied to the fiber. The frequency shift tuning with the range up to 140 cm−1 has been observed for an external stress of 0.3 kg/cm in the test stress-induced birefringent fiber.
Broadband triboluminescence in silica core fiber optic waveguides
Authors: Smiel A. J. , Fischer T. A.
Published: February 2003

This letter describes the first observation of broadband, shock-induced luminescence in silica core fiber optic waveguides on a single-event basis. Spectra recorded with an optical multichannel analyzer suggest that at least two different types of luminescence centers are responsible for this emission. The degree to which each type of luminescence center is created and/or excited is found to depend upon the detailed dynamics of the crushing.
Imaging antenna array at 119 μm
Authors: Neikirk Dean P. , Tong Peter P. , Rutledge David B. , Park Hyeon , Young Peter E.
Published: February 2003

A focal-plane imaging antenna array has been demonstrated at 119 μm. The array is a line of evaporated silver bow-tie antennas with bismuth microbolometer detectors on a silicon substrate. Radiation is coupled into the array by a lens placed on the back of the substrate. The bolometers are thermally isolated from the silicon substrate with a half-micron layer of polyimide. The array performance is demonstrated by coherent imaging of a series of holes at half the diffraction-limited cut-off frequency.
Investigation of fluorine-concentration profiles in pulsed-laser-irradiated BF+2 -implanted silicon single crystals
Authors: Nylandsted-Larsen A. , Jarjis R. A.
Published: February 2003

The technique of 19F(p,αγ) 16O resonant nuclear reaction is applied to pulsed-laser-irradiated BF+2 -implanted silicon single crystals for the determination of fluorine-concentration profiles by γ-ray counting. Out-diffusion of fluorine is observed for all applied laser-energy densities. For laser-energy densities typical for complete recrystallization of the damaged surface layer, about 50% of the implanted fluorine is still retained in this layer.
AlGaAs inverted strip buried heterostructure lasers
Authors: Blauvelt H. , Margalit S. , Yariv A.
Published: February 2003

Inverted strip buried heterostructure lasers have been fabricated. These lasers have threshold currents and quantum efficiencies that are comparable to those of conventional buried heterostructure lasers. The optical mode is confined by a weakly guiding strip loaded waveguide which makes possible operation in the fundamental transverse mode for larger stripe widths than is possible for conventional buried heterostructure lasers. Scattering of the laser light by irregularities in the sidewalls of the waveguide, which can be a serious problem in conventional buried heterostructure lasers, is also greatly reduced in these lasers.
New heterojunction InGaAsP/InP laser with high-temperature stability (T0 = 180 K)
Authors: Yano Mitsuhiro , Morimoto Masahiro , Nishitani Yorimitsu , Takusagawa Masahito
Published: February 2003

This letter proposes and demonstrates the operation of a new heterojunction InGaAsP/InP laser, a double-carrier-confinement heterojunction (DCC-heterojunction) laser. This laser is fabricated by incorporating a p-InGaAsP second well layer into a p-InP clad layer of the conventional InGaAsP/InP double-heterojunction laser. With this laser, excellent temperature stability of threshold current [T0 is 180 K in the temperature range of 20–100 °C when threshold current varies with exp(T/T0)] and high external differential quantum efficiency (more than 45% at 100 °C) were achieved. Beam divergence perpendicular to the junction plane was also much improved (less than 25°).
Infrared laser-induced desorption of H2O and hydrocarbons from optical surfaces
Authors: Allen Susan D. , Porteus J. O. , Faith W. N.
Published: February 2003

Laser-induced desorption has been demonstrated for strongly optically absorbing molecules on nominally transparent substrates. Both H2O and hydrocarbon contaminants were desorbed using a pulsed HF/DF laser source at 2.8 and 3.7 μm. Following laser desorption of H2O, the 2.8-μm damage threshold in CaF2 roughly doubled. Surface mapping of H2O desorption with a 120-μm-diam focal spot showed considerable variation with spatial position on polished CaF2, indicating localized concentrations of adsorbate.
Autoacceleration of high power electron beams
Authors: Friedman M.
Published: February 2003

The mutual interaction between a 70-kA intense relativistic electron beam and a passive structure increased the kinetic energy of electrons from 4.2 to 7.4 MeV. This process (known as autoacceleration) should be capable of generating electron beams with even higher particle energy and with currents ≳ 100 kA.
Effect of substrate surfaces on the formation of nematic phase at the isotropic→nematic transition
Authors: Yokoyama Hiroshi , Kobayashi Shunsuke , Kamei Hirotake
Published: February 2003

The effect of substrate surfaces on the formation of the nematic phase at the isotropic→nematic transition of a mixture of 4-cyano-4′-n-pentylbiphenyl and hexamethyl-benzene was studied by observing the textures with a polarizing microscope and measuring the birefringence induced by the substrate in the isotropic phase for two typical homogeneous aligning surface treatments: (1) polyvinylalcohol coating followed by rubbing and (2) SiO oblique evaporation. The two treatments resulted in completely different textures at the transition depending on the magnitude of the ordering, or equivalently the birefringence, induced by the substrate in the isotropic phase.
Properties of TiN obtained by N+2 implantation on Ti-coated Si wafers
Authors: Armigliato A. , Celotti G. , Garulli A. , Guerri S. , Lotti R. , Ostoja P. , Summonte C.
Published: February 2003

Titanium nitride films have been prepared by implanting 3.4×1017 cm−2 N+2 ions in 600-Å-thick titanium layers deposited on silicon single crystals. Unlike the films obtained by evaporation or sputtering, both low electrical resistivity and fairly good optical properties were found even in the as-implanted samples. Moreover, thermal treatments up to 700 °C performed both in vacuum and H2 atmosphere resulted in a further improvement of the overall films characteristics. This opens interesting perspectives of applications for TiN as a transparent (antireflective) conducting material in photovoltaic field, which are presently being investigated.
Generalized stream function representation for current flow in semiconducting media
Authors: Pattanayak Deva N. , Williams Ross A. , Poksheva John G.
Published: February 2003

Stream functions comprised of stream vectors and stream potentials are introduced to represent electron and hole current densities in a semiconductor. These stream functions satisfy electron and hole current continuity equations individually for general cases involving, for example, transient behavior and recombination-generation processes. The terminal currents are expressed in terms of the stream functions. The nonuniqueness property of the stream functions is discussed briefly.
Quasi-equilibrium beam-plasma dynamics
Authors: McCorkle R. A.
Published: February 2003

Intense charged particle beams in plasmas are subject to current limitation for single beam propagation. The limiting mechanism is excessive self-focusing due to net current and space-charge overneutralization effects. A nearly constant minimum plasma impedance of ∼30 Ω is presented to beams with Lorentz factors γ≳1.1.
Morphological fluctuation and electrical properties of sputtered hydrogenated silicon
Authors: Shirafuji J. , Matsui H. , Narukawa A. , Inuishi Y.
Published: February 2003

Electrical properties and x-ray small angle scattering have been measured on rf-sputtered Si:H alloys deposited at various hydrogen partial pressures of argon and hydrogen mixture gas with a constant total pressure. When the hydrogen partial pressure exceeds 40%, microcrystalline zone of about 200 Å in diameter is formed and photoexcited carriers show nondispersive transport, instead of dispersive transport which is typical of rf-sputtered a-Si:H.
Damage induced through megavolt arsenic implantation into silicon
Authors: Byrne P. F. , Cheung N. W. , Sadana D. K.
Published: February 2003

An arsenic beam of 11 MeV was used to achieve a layer of heavily doped silicon centered at 4.4 μ below the surface. Both liquid nitrogen and water-cooled (100) silicon substrates were exposed to an arsenic dose of 1.9×1015 ions/cm2. Before furnace annealing, cross-sectional transmission electron microscopy (XTEM) shows buried amorphous regions for both samples with a wider amorphous region for the LN-cooled sample. The depth distribution of secondary defects on subsequent annealing qualitatively resembles those obtained by lower energy implantation, and the details depend strongly on the substrate temperature during implantation. Secondary ion mass spectrometry (SIMS) was used to verify LSS calculations for the arsenic distribution.
Effect of bias on radiation-induced paramagnetic defects at the silicon-silicon dioxide interface
Authors: Lenahan P. M. , Dressendorfer P. V.
Published: February 2003

Electron spin resonance measurements have been made on gamma-irradiated (111) Si/SiO2 structures as a function of bias across the oxide. We observe a large change in the density of radiation-induced paramagnetic Pb centers with bais. We conclude that Pb defects (trivalent silicons at the Si/SiO2 interface) account for a very large portion of the radiation-induced interface states.
Variation in waveguides fabricated by immersion of LiNbO3 in AgNO3 and TlNO3: The role of hydrogen
Authors: Jackel J. L. , Rice C. E.
Published: February 2003

Optical waveguides fabricated in LiNbO3 by what has previously been described as silver-lithium or thallium-lithium ion exchange in the molten nitrates AgNO3 or TlNO3 have not generally been reproducible. We show that the large increases of the extraordinary index (Δne = 0.12), which are observed intermittently, result not from introduction of the heavy ions, Ag+ or Tl+, but from hydrogen-lithium exchange, which occurs when hydrogen is present as an impurity in the melts.
New analysis of field-effect conductance in hydrogenated amorphous silicon thin-film transistors
Authors: Lee Sanboh , Chen Inan
Published: February 2003

The field-effect conductance of hydrogenated amorphous silicon thin-film transistors has been calculated as a function of the gate voltage. This analysis differs from the existing ones in taking into account (1) the space charge due to excess free carriers, in addition to that caused by modulation of bulk localized state occupancy, and (2) the charge in the surface states in the determination of the boundary condition. Numerical results are presented to demonstrate the significance of these effects.
Technique for the inversion of backscattered elastic wave data to extract the geometrical parameters of defects with varying shape
Authors: Cohen-Tenoudji F. , Tittmann B. R. , Quentin G.
Published: February 2003

A technique is described for the inversion of elastic scattering data in order to extract the geometrical properties of a scatterer embedded in a solid. The technique is in part based on the Kirchhoff approximation. Results are presented for the inversion of theoretical and experimental scattering data for a variety of shapes including spherical, ellipsoidal, and disc-shaped voids as well as a compound void consisting of two overlapping spherical voids of different radii.
Dependence of the electron cross section for the acceptor gold level in silicon on the gold to donor ratio
Authors: Morante J. R. , Carceller J. E. , Herms A. , Cartujo P. , Barbolla J.
Published: February 2003

Current transient spectroscopy was adapted to quasi-compensated samples for measurement of the electron cross section for the acceptor gold level in Czochralski-grown silicon in samples with various ratios of the deep level concentration NT to the shallow level concentration ND up to NT/ND = 0.83. The value obtained, (7.05±1)×10−17 cm2, appears to be independent of the NT/ND ratio, in good agreement with previous results for lower NT/ND ratios.
Behavior of the 0.82 eV and other dominant electron traps in organometallic vapor phase epitaxial AlxGa1−xAs
Authors: Matsumoto Takashi , Bhattacharya Pallab K. , Ludowise M. J.
Published: February 2003

Thermal emission and capture properties of three dominant electron traps in organometallic vapor phase epitaxial AlxGa1−xAs have been studied by transient capacitance measurements. The traps have activation energies ΔET = 0.82±0.01, 0.62±0.02, and 0.38±0.02 eV, which remain invariant with x. The thermal capture cross section of the traps, however, decreases with increasing x. These results, together with the annealing behavior of the traps, add more evidence to the fact that the 0.82-eV trap, commonly known as the EL2 center, is related to a Ga vacancy. The 0.82- and 0.38-eV traps exhibit barriers to electron capture ∼0.06–0.08 eV and the concentration of the 0.62- and 0.38-eV traps increases with increasing x.
Picosecond time-resolved plasma and temperature-induced changes of reflectivity and transmission in silicon
Authors: Liu J. M. , Kurz H. , Bloembergen N.
Published: February 2003

A pump-and-probe technique is used to perform picosecond time-resolved measurements of reflectivity and transmission changes in silicon. The results provide direct evidence that lattice heating, melting, or boiling can occur on a picosecond time scale. Detailed analysis of the data provides information about the dynamics of the electron-hole plasma prior to melting and the kinetics of ultrafast phase transitions and crystal regrowth.
Picosecond optical electronic sampling: Characterization of high-speed photodetectors
Authors: Auston D. H. , Smith P. R.
Published: February 2003

A photoconducting sampling gate which is triggered by a picosecond optical pulse and has an aperture of approximately 12 ps has been used to measure accurately the response of a high-speed, solid-state photodiode. The sample gate, which is made from a radiation-damaged semiconductor, is demonstrated to have better speed, lower noise level, negligible jitter, and fewer reflections than conventional sampling oscilloscopes. In addition, it can be used over a wide temperature range by direct mounting in a variable temperature cryostat.
High-power nitrogen laser
Authors: Armandillo E. , Kearsley A. J.
Published: February 2003

The design and performance of a discharge excited N2 laser which can produce pulses of 337-nm radiation with peak powers in excess of 5 MW and durations of 4 ns [full width at half-maximum (FWHM)] are described. The output beam is reproducible, uniform, and of large (25×35 mm) cross section. The peak value of the radiance is greater than 3×1011 Wsr−1.
Magnetoresistive waves in plasmas
Authors: Felber F. S. , Hunter R. O. , Pereira N. R. , Tajima T.
Published: February 2003

The self-generated magnetic field of a current diffusing into a plasma between conductors can magnetically insulate the plasma. Propagation of magnetoresistive waves in plasmas is analyzed. Applications to plasma opening switches are discussed.
Resonance phenomena on bias current dependence of AlGaAs double heterostructure laser amplifier
Authors: Watanabe Nobutaka , Sakuda Kyohei
Published: February 2003

We report the first observation of the resonance phenomena on the bias current dependence of the amplified light output for AlGaAs double heterostructure laser. We also show that this resonance phenomenon is mainly caused by the change in the refractive index of the active layer due to the bias current change in terms of the simple theoretical calculations taking into account the effect of the refractive index change in the active layer.
‘‘Temporal tuning’’ of XeCl laser pulse width from 5 ns to less than 500 ps using saturable absorber dyes
Authors: Varghese Thomas
Published: February 2003

The width of XeCl laser pulse from a discharge laser has been ’’temporally tuned’’ from 5 ns to less than 500 ps using saturable absorber dyes. A maximum pulse shortening of ≊20 has been achieved in a single pass, single stage saturable absorber pulse compression scheme. Pulse shortening characteristics were found to be reproducible for single shot and repetition rate operation.
Work function of oxygen exposed lead and lead/indium alloy films
Authors: Gundlach K. H. , Hellemann H. P. , Hölzl J.
Published: February 2003

The effect of indium in superconducting tunnel junctions with lead/indium alloy base electrodes is investigated by measuring the vacuum work function of lead, indium, and lead/indium alloy films. It is found that the anomalous decrease of the work function of lead upon exposure to oxygen, explained by the penetration of oxygen into the inner surface of the lead film, is reversed into a slight increase in work function when some indium is added to the lead. This result indicates that the addition of indium provides a protection by suppressing the penetration of oxygen (and probably other gases) into the interior of the thin film.
Negative dynamic conductance from photon-assisted tunneling in superconducting junctions
Authors: Roukes Michael L. , Wilkins John W.
Published: February 2003

We show that a superconductor-insulator-superconductor (SIS) junction may exhibit regions of negative dynamic conductance if it is irradiated by a time-varying signal source which deviates from the conventionally treated constant ac voltage limit. This phenomenon reflects the strong dependence of the junction absorption cross section upon dc bias voltage. Analytic estimates for the magnitude of the negative conductance and its impact upon the frequency down conversion process are obtained in the constant ac current limit.
Excess solubility of oxygen in silicon during steam oxidation
Authors: Mikkelsen J. C.
Published: February 2003

1 8O was introduced into float-zone Si wafers during oxidation in H2 18O at temperatures from 600–1240 °C, and the 18O concentration profiles were measured by secondary ion mass spectrometry. The oxygen solubility, as determined from the surface 18O concentrations, was found to be significantly higher in as-oxidized wafers than in post-oxidation annealed wafers. The temperature dependence of the as-oxidized solubility, Sox, can be described by Sox(T)=1.2×1020 cm−3 exp(−0.67 eV/kT), with a higher activation energy of 1.02 eV for the equilibrium solubility. These results are compared with other published oxygen solubility determinations.
Plasma channel formation with ultraviolet lasers
Authors: Frost C. A. , Woodworth J. R. , Olsen J. N. , Green T. A.
Published: February 2003

The beam from a low-divergence KrF laser (λ=248 nm) has been used to generate long plasma channels in low pressure gases. Current-carrying channels 60 cm in length were produced with 5 mJ of laser energy. Channels exceeding 1 m in length were also initiated. The ionization source producing the plasma is laser-induced resonant two-step photoionization of organic molecules which are seeded in a buffer gas.
Raising damage thresholds of gradient-index antireflecting surfaces by pulsed laser irradiation
Authors: Swain J. E. , Lowdermilk W. H. , Milam D.
Published: February 2003

Gradient-index antireflecting surfaces produced by neutral solution processing have a median surface damage threshold of 12 J/cm2 for 1-ns, 1064-nm pulses. We have found that the threshold can be increased to 25 J/cm2 by irradiating the surface with 1064-nm wavelength pulses with fluence below the initial 12-J/cm2 threshold. Damage thresholds, both before and after this treatment, increased as the square root of the pulse duration in the 1–20-ns range.
B → X transitions in HgCl and HgI
Authors: Tellinghuisen Joel , Tellinghuisen Patricia C. , Davies Sue A. , Berwanger Patrick , Viswanathan K. S.
Published: February 2003

The B → X spectra of HgCl and HgI are studied at high resolution for the single isotopic species, 200Hg35Cl, 200Hg127I, and 200Hg129I. For HgI the analysis indicates that the v″ numbering should be decreased by one unit from the previous assignment. For both molecules the analyses deviate progressively from the previous assignments at high v″, extrapolating to lower estimates of the ground-state dissociation energies. Franck–Condon calculations yield ΔRe (=Re′ −Re″) =0.60Å for HgCl and 0.49 Å for HgI. The strongest laser features previously reported for HgCl occur near the heads of the overlapped 0–22, 1–23, 2–24, and 3–25 bands. The HgI laser operates in the region of the 0–14, 0–15, 1–15, 1–16, 2–17, and 2–18 bands.
Low threshold InGaAsP/InP lasers with microcleaved mirrors suitable for monolithic integration
Authors: Koren U. , Hasson A. , Yu K. L. , Chen T. R. , Margalit S. , Yariv A.
Published: February 2003

Low threshold InGaAsP/InP injection lasers on semi-insulating InP substrates have been developed with mirrors fabricated by the microcleavage technique. Miniature suspended bridges containing the laser channels have been formed and then microcleavage has been accomplished by the use of ultrasonic vibrations. Lasers with current thresholds as low as 18 mA with 140-μm cavity length and with 35–45% differential quantum efficiency have been obtained.
200-MHz electrodeless discharge excitation of an XeF laser
Authors: Christensen C. P. , Waynant R. W.
Published: February 2003

Two hundred megahertz electrodeless rf discharge excitation of an XeF laser is reported. Laser output of total duration exceeding 300 ns is observed. Onset of discharge inhomogeneity is found to limit duration of the laser pulse and to influence recovery of the active medium.
Metalorganic chemical vapor deposition of very thin (≂2 μm), oriented GaAs layers on tungsten substrates
Authors: Shastry S. K.
Published: February 2003

This letter describes a novel technique for the deposition of very thin (≂2 μm), pinhole-free gallium arsenide layers, with large grains (≂ 7 μ) and (110) preferred orientation, on tungsten substrates, by the metalorganic chemical vapor deposition process (MOCVD). The deposition was performed at ∼930 °C with a controlled undercooling of 2°/min, and under a high trimethylgallium flux, corresponding to a gallium arsenide growth rate of 0.4 μm/min. The deposition process is explained by the vapor-liquid-solid growth mechanism in which gallium arsenide, in the chemical vapor deposition environment, is formed as in solution growth. The need for undercooling during the deposition process is outlined in terms of gallium arsenide nucleation. It is proposed that such nucleation in CVD occurs by a priori nucleation of gallium, and by subsequent supersaturation of these gallium nuclei by arsenic.
Suppression effect upon oxygen precipitation in silicon by carbon for a two-step thermal anneal
Authors: Ogino Masanobu
Published: February 2003

The suppression effect on oxygen precipitation by carbon was observed under a certain heat treatment condition. The amount of precipitate oxygen in a high carbon silicon crystal is less than that in a low carbon silicon crystal, when silicon crystals are heat treated by the two-step thermal anneal (700 °C anneal+1000 °C anneal), whose first step annealing time is long. This is caused by the generation of too many precipitate nuclei during the first step thermal anneal. Growth rate for small precipitates is retarded. Carbon has the enhancement effect on oxygen precipitation during the first step anneal at 700 °C, but no enhancement effects during the second step anneal at 1000 °C.
Trap creation in channel oxides due to ion penetration of polycrystalline silicon
Authors: Smeltzer R. K.
Published: February 2003

Deep penetration of polycrystalline silicon by high-energy phosphorus ions was shown to produce large concentrations of hole traps in metal-oxide-semiconductor devices. An excess concentration of hole traps was found to exist even in devices whose characteristics were initially unaffected by the deep tail on the phosphorus implantations. To detect the presence of the traps, devices were subjected to ionizing radiation which produces free carriers in the channel oxide. A strong dependence of hole trap generation on the implantation dose was found up to very high doses. A secondary ion mass spectrometry profile of implanted phosphorus in polysilicon also clearly shows a large phosphorus concentration in the deep tail of the implantations.
Hot-electron luminescence in aged electrodeposited CdSe liquid-junction solar cell
Authors: Silberstein R. P. , Tomkiewicz Micha
Published: February 2003

We have utilized Raman spectroscopy and scanning Auger electron spectroscopy (AES) to probe the surface of polycrystalline, electrodeposited CdSe photoelectrodes which have been aged in a polysulfide electrolyte under illumination and in darkness. We have observed characteristic ‘‘hot-electron’’ luminescence at multiples of ωLO (CdS)=305 cm−1 in the light-aged electrode, indicating that a surface layer of CdS has been formed. AES profiling shows that extensive substitution of S for Se has occurred, in the light-aged electrode alone, to a depth of ∼600 Å. Measurements at 300 K suggest that Raman scattering can be a useful, in situ, contactless, nondestructive probe of CdS formation.
Improved photoluminescence of organometallic vapor phase epitaxial AlGaAs using a new gettering technique on the arsine source
Authors: Shealy J. R. , Kreismanis V. G. , Wagner D. K. , Woodall J. M.
Published: February 2003

Using an aluminum-gallium-indium ternary melt for the removal of oxygen and moisture from the arsine source, substantial improvement in the quality of organometallic vapor phase epitaxial AlGaAs can be achieved. The arsine is bubbled through the ternary melt at room temperature prior to its introduction into a low-pressure reactor. Low-temperature photoluminescence spectra indicate an improvement in the sharpness of the bound exciton transition after the use of this gettering technique.
New graded band-gap picosecond phototransistor
Authors: Capasso F. , Tsang W. T. , Bethea C. G. , Hutchinson A. L. , Levine B. F.
Published: February 2003

We demonstrate the first phototransistor with a graded band-gap base. The AlGaAs/GaAs wide gap emitter molecular beam epitaxial structure, when operated at zero bias, behaves as an ultrahigh speed photodetector. The pulse response is symmetric with an intrinsic rise time ≤20 ps and a full width at half-maximum ≤40 ps. When operated at reverse bias the detector behaves as a phototransistor. The response time of this device demonstrates that the base transit time is greatly reduced by the quasi-electric field in the base. This feature combined with the abrupt wide gap emitter may be used to implement new high-speed transistors.
Dispersion of the saturated current in GaAs from dc to 1200 GHz
Authors: Allen S. J. , Allyn C. L. , Cox H. M. , DeRosa F. , Mahoney G. E.
Published: February 2003

The frequency dependence of the small-signal conductance of GaAs epilayers biased into current saturation is measured from dc to 1200 GHz. The experiments directly expose the effective energy and momentum relaxation rates in the high field anode domain. Velocity overshoot appears as a recovery of the small-signal device conductance at high frequencies.
Seeded recrystallization of thick polysilicon films on oxidized 3-in. wafers
Authors: Celler G. K. , Robinson McD. , Lischner D. J.
Published: February 2003

The first successful seeded recrystallization of thick, >10 μm Si films deposited on SiO2 is reported. A method of lateral epitaxial growth over oxide (LEGO) has been developed, in which the thick polycrystalline Si films are completely melted by intense photon flux. The epitaxial recrystallization which follows starts at the seeding regions, spaced as far as 1 mm apart, and results in single crystalline Si-on-insulator with a low density of defects. The process is carried out in a special furnace with samples placed between a bank of tungsten halogen lamps and a water-cooled base, allowing uniform and bow-free crystallization of complete 3-in. wafers in ∼60 s.
Discharge pumped ZnI (599–606 nm) and CdI (653–662 nm) amplifiers
Authors: Greene D. P. , Eden J. G.
Published: February 2003

Peak small-signal gain coefficients (γ0) of 2.0% cm−1 and 0.7% cm−1 have been obtained on the B→X bands of CdI (cadmium monoiodide) and ZnI, respectively, in a UV-preionized, high-temperature (650≲T≲710 K) transverse discharge. For CdI, γ0 is greater than 1% cm−1 over a 90-Å (653≤λ≤662 nm) spectral region.
Direct gain modulation of a semiconductor laser by a GaAs picosecond optoelectronic switch
Authors: Göbel E. O. , Veith G. , Kuhl J. , Habermeier H.-U. , Lübke K. , Perger A.
Published: February 2003

We report a novel application of high-speed optoelectronic switches for direct gain modulation of semiconductor lasers. A GaAs/GaAlAs buried heterostructure laser is driven by a Cr-doped GaAs photoconducting switch activated by a synchronously mode-locked cw dye laser. Infrared light pulses of 55-ps width are emitted from the semiconductor laser.
Imaging through a distorting medium with and without phase conjugation
Authors: Feinberg Jack
Published: February 2003

The problem of sending an optical image through a phase-distorting medium is discussed. It is shown that a simple lens is sufficient for transmitting the intensity of an image through a thin distorter. A phase conjugator and a lens can transmit the amplitude of an image through a thin distorter. Neither can transmit an undistorted image through a thick distorter. These results are experimentally verified using a self-pumped phase conjugator.
Ion bombardment control of morphology during the growth of hydrogenated amorphous silicon thin films by reactive ion beam deposition
Authors: Kasdan A. , Goshorn D. P.
Published: February 2003

Low-energy ion bombardment of hydrogenated amorphous silicon thin films during growth is shown to have a pronounced effect on growth morphology. The films studied have been prepared by reactive ion beam sputtering. For substrate temperatures ≳200 °C and hydrogen content in the films ≳20 at. %, a growth instability develops, which results in a rough film morphology. Ion bombardment during growth stabilizes the film growth, and results in smooth morphologies.
Rate and efficiency of I2 dissociation in the presence of O2(1Δ)
Authors: Hays G. N. , Fisk G. A.
Published: February 2003

We adopt a simplified kinetic scheme to account for the functional dependence of the observed, rapid dissociation of I2 in the presence of O2(1Δ). Phenomenologically, the functional form for I2 disappearance was found to be d[I2]/dt=−[(6±4)×10−29 cm6 s−1][I2][O2(1Δ)]2 for O2(1Δ) concentrations greater than 25 mTorr. Moreover, analysis of our data indicates that three O2(1Δ) molecules are expended in producing two iodine atoms.
Metal-oxide-semiconductor field-effect transistors and a ring oscillator fabricated in laser-recrystallized polycrystalline silicon islands
Authors: Nishimura T. , Akasaka Y. , Nakata H. , Ishizu A.
Published: February 2003

Directions of grain boundaries in laser-recrystallized polycrystalline silicon (polysilicon) islands are found to be arranged along with the laser scan direction, and are connected to the electrical characteristics of metal-oxide-semiconductor field-effect transistors (MOSFET’s) fabricated in polysilicon islands. When the laser scan is parallel to the channel direction, grain boundaries work as fast-diffusion paths of arsenic from source and drain into the channel and a decrease of effective channel length of the MOSFET results. But when the laser scan is perpendicular to the channel direction, few grain boundaries are contributed to diffusion paths of arsenic. A maximum electron mobility of 590 cm2/V s approaching that of a single crystalline silicon can be obtained in devices with a channel length of 3 μm, though grain boundaries work as additional potential barriers for carriers. A nine-stage ring oscillator is fabricated by applying these results. A minimum propagation delay of 38 ns is obtained.
Magnetic field gradient dependence of the electrical conductivity in a low resistive garnet film
Authors: De Gasperis Paolo , D’Amico Arnaldo
Published: February 2003

A dramatic dependence of the resistivity on an external magnetic field gradient has been observed for the first time in a p-type semiconducting calcium-doped yttrium iron garnet film. In a homogeneous gradient a steady increase of the conductivity (up to 26%) is detected, while by applying a nonuniform gradient only transient variations are found. These results are interpreted as due to an intrinsic physical process independent on the nature of the sputtered contacts. A hole trapping/detrapping mechanism is suggested to qualitatively explain the results in a uiform field gradient and, in particular, the long relaxation times measured.
Schlieren method as applied to magnetic recording heads in the scanning electron microscope
Authors: Wells Oliver C. , Brunner Matthias
Published: February 2003

The fringing field above the surface of a magnetic recording head or magnetic tape can be studied in transmission in the scanning electron microscope (SEM) by either the ‘‘image distortion’’ or the ‘‘Schlieren’’ method. In the image distortion method, the magnetic field is calculated from the distortion caused by the fringing field to the image of either the specimen itself, or of a reference mesh. The Schlieren image shows a contour of equal field-times-distance integral (either for the total field or for a specified component of the field) directly. Methods used previously to show the contours of constant values of this integral in the SEM can be improved by the use of the rocking scanning mode about the plane of the aperture stop. The Schlieren method can also give a two-part image in which one-half of the micrograph shows the surface of the head viewed at a glancing angle, while the other half of the image shows the fringing field. This method has the potential for stroboscopic operation.
Remote thermal imaging with 0.7-μm spatial resolution using temperature-dependent fluorescent thin flims
Authors: Kolodner Paul , Tyson J. Anthony
Published: February 2003

We have applied the recently developed technique of fluorescent thermal imaging to measure the surface temperature profile of a test sample with unprecedented temperature and spatial resolution. A particularly simple temperature profile was produced by passing an electrical current through a long, unresolvably thin metal stripe on a glass substrate. The sample was coated with a fluorescent thin film whose fluorescence efficiency decreases with increasing temperature. Digital processing of the fluorescence image produces a quantitative surface temperature map with simultaneous temperature and spatial resolutions of 0.08 °C and 0.7 μm, respectively. This spatial resolution approaches for the first time the dimensions of state-of-the-art integrated circuits. Extension of this technique into the nanosecond time domain will allow new advances in the fields of photothermal microscopy, integrated circuit diagnostics, and thermal transport measurements.
Changes in the local chemical composition during the Hg1−xCdxTe-Al interface formation
Authors: Daniels R. R. , Margaritondo G. , Davis G. D. , Byer N. E.
Published: February 2003

Photoemission spectroscopy experiments with a synchrotron radiation source demonstrate that Hg depletion occurs near the surface during Al deposition on Hg0.72Cd0.28Te. The measured interface position of the Fermi level suggests that this depletion influences the effective Schottky barrier height.
Gate-width dependence of radiation-induced interface traps in metal/SiO2/Si devices
Authors: Chin M. R. , Ma T. P.
Published: February 2003

The density of radiation-induced interface traps in a post-metal-annealed (PMA) Al-gate metal-oxide-semiconductor (metal/SiO2/Si) depends strongly on the linewidth of the metal gate over a wide range (1–750 μm) of linewidths studied, although there is no discernible dependence prior to the irradiation. The dependence is such that the narrower the linewidth, the fewer the radiation-induced interface traps. Such dependence has been generally observed for both p- and n-type Si samples, for oxides grown in dry O2 or steam at temperatures over a wide range (900–1000 °C), and for PMA treatment either in dry N2 or in forming gas (10% H2+90% N2). The results can be qualitatively explained by a model based on the gate linewidth dependence of the SiO2/Si interfacial stress prior to irradiation, which affects the radiation sensitivity in accordance with the strained bond model.
Relation between current-voltage characteristics and interface states at metal-semiconductor interfaces
Authors: Barret C. , Muret P.
Published: February 2003

In the case of metal-covalent semiconductor interfaces, the ‘‘pinning’’ of the metal Fermi level was attributed to large densities of interface states by Bardeen, 35 years ago. These interface states are usually thought to be in equilibrium with the metal. But capacitance measurements show unambiguously the existence of states in equilibrium with the semiconductor, even for cleaved contacts. Freeouf argued recently that this kind of states would influence I-V characteristics. Here, some examples of such a correlation between interface states spectra and I-V nonidealities are presented for Au-InP and Au-Si contacts.