Showing papers by "Alcatel-Lucent published in 1978"

Quantum-defect theory of heats of formation and structural transition energies of liquid and solid simple metal alloys and compounds

Abstract: The tables of $l$-dependent ion-core radii ($l=0,1,2$) derived from free-ion quantum defects and previously presented by Simons and Bloch are extended to include halogens and the group-$\mathrm{I}\ensuremath{-}B$ metals (Cu, Ag, and Au). From these radii hybridized bond-orbital coordinates with $\ensuremath{\sigma}$ and $\ensuremath{\pi}$ character are formed. The dual bond-orbital coordinates are used to discuss the structures, uniaxial distortions, and melting points of more than 100 simple binary compounds belonging either to the octet family ${A}^{N}{B}^{P\ensuremath{-}N}$ with $P=8$ or to the suboctet family $2\ensuremath{\le}P\ensuremath{\le}6$. Two conclusions emerge: the quantum bond-orbital $\ensuremath{\sigma}$ and $\ensuremath{\pi}$ dual coordinates describe the physical properties of these materials much more accurately than traditional classical coordinates such as size and electronegativity, and the dual quantum coordinates are equally accurate for octet and suboctet compounds. The success of the quantum coordinates implies that bond charges with $\ensuremath{\sigma}$ and $\ensuremath{\pi}$ components make important contributions to the structural energies of these materials. The dual coordinate cellular scheme developed by Miedema and co-workers to describe the sign of the heat of formation of liquid and solid metal alloys is examined within the context of orbital, $l$-dependent ion-core radii. We show that Miedema's original coordinate set is unphysical, but that his inductively revised coordinates which are derived from more than 500 binary phase diagrams are remarkably accurate. Apparent irregularities in the revised coordinates are shown by comparison with the orbital shell model to be correct and the consequence of core shell structure.

Periodic regrowth phenomena produced by laser annealing of ion‐implanted silicon

Abstract: We have discovered that interference effects extant during pulsed laser irradiation annealing of ion‐implanted silicon produce periodic property variations in the annealed material that mimic the interference pattern. These are manifest at near‐annealing threshold power densities as surface ripple and at higher power densities may be revealed by etching. The surface ripple observed at low power densities is correlated with the occurrence of polycrystalline silicon regions in the annealed material. Our observations suggest that surface melting and epitaxial regrowth are responsible for the annealing effect.

The band structure dependence of impact ionization by hot carriers in semiconductors: GaAs

Abstract: We present the first systematic study of the dependence of impact ionization by electrons and holes upon the details of the electronic band structure. Our measurements, made in GaAs, establish the crucial role of the ionization threshold energy, and its location in the Brillouin zone, in determining the ionization rates. This relationship is apparent in the dependence of impact ionization rates on the temperature of the lattice, compositional changes for the alloy GaAs 1- x Sb x , and the orientation and strength of the electric field. The strong dependence of impact ionization upon specific features of the electronic band structure is a new principle which can be used to study the nature of electronic states in a wide variety of semiconductors through hot-carrier behavior.

Enhanced photoelectrochemical solar‐energy conversion by gallium arsenide surface modification

Abstract: In the n‐GaAs/Se=–Se=x–OH−/C liquid junction solar cell, modification of the semiconductor surface by incorporation of ruthenium increases both the fill factor and the open‐circuit voltage and improves the reproducibility of performance. The power conversion efficiency of the modified cell is 12% under ∼100 mW/cm2 sunlight. Surface metal atoms or ions are shown to alter GaAs cell behavior widely; Ru represents a case for which the effect on cell performance is both positive and persisting.

High-resolution 13C nuclear magnetic resonance studies of glucose metabolism in Escherichia coli.

Abstract: High-resolution 13C nuclear magnetic resonance spectra of suspensions of Escherichia coli cells have been obtained at 90.5 MHz by using the Fourier transform mode. Anaerobic cells incubated with [I-13C]glucose show a time course of glycolysis in which the alpha and beta glucose anomers disappear at different rates, lactate, succinate, acetate, alanine, and valine accumulate as end products of glycolysis, and fructose bisphosphate appears as an intermediate. It is shown that fructose bisphosphate is labeled at C-1 and C-6 during [I-13C]-glucose catabolism. Upon oxygenation, glutamate appears with the 13C ENRICHMENT AT THE C-4, C-3, and C-2 positions, with the C-4 most intense. From the position of the 13C label we conclude that valine is formed by condensation of pyruvate and that carbon enters the tricarboxylic acid cycle mainly through acetyl CoA.

31P nuclear magnetic resonance studies of bioenergetics and glycolysis in anaerobic Escherichia coli cells

Abstract: 31P nuclear magnetic resonance spectra of glycolyzing, anaerobic Escherichia coli cells and their perchloric acid extracts were obtained at 145.7 MHz. Time-dependent intracellular concentrations of nucleoside di- and triphosphates, Pi, and sugar phosphates were measured during glycolysis with 2-min resolution, while intracellular and extra-cellular pH values were monitored simultaneously. Upon glucose addition, anaerobic E. coli cells rapidly produce acids and develop a transmembrane pH gradient (delta pH). Glycolysis rates were calculated from the changes in the external pH. It was found that glycolysis rates are strongly dependent on internal pH, sharply decreasing when the pH drops below approximately 7.2. The ATPase inhibitor, dicyclohexylcarbodiimide (DCCD), prevented NTP hydrolysis and inhibited delta pH formation. The uncoupler, carbonyl cyanide p-triflouromethoxyphenyl hydrazone (FCCP), drastically reduced both the delta pH and the NTP level. When the cells were previously treated with DCCD, FCCP collapsed the delta pH while the NTP levels remained high. It is concluded that ATP produced by glycolysis is hydrolyzed by the membrane ATPase to generate a delta pH and that FCCP stimulates ATP hydrolysis by ATPase and collapses the proton gradient.

Head-group conformation in phospholipids: a phosphorus-31 nuclear magnetic resonance study of oriented monodomain dipalmitoylphosphatidylcholine bilayers.

Abstract: Angular-dependent 31P NMR spectra of oriented biaxial monodomain DPPC.H2O multilayers are employed to study head-group conformation in this phospholipid. The results indicate that the O-P-O plane of the phosphate, where the O's are the nonesterified oxygens of the phosphodiester, is tilted at 47 +/- 5 degrees with respect to the bilayer normal. This PO4 orientation could result in the choline moiety being extended parallel to the bilayer plane, and it will explain the breadth of the axially symmetric 31P powder spectrum observed for DPPC in excess water. This work is the first direct observation of this conformation for lecithins and it illustrates the utility of high-resolution solid-state NMR in structural studies of disordered systems.

Solid-phase epitaxy of implanted silicon by cw Ar ion laser irradiation

Abstract: Arsenic‐ and antimony‐implanted silicon wafers have been annealed by a cw Ar ion laser. Glancing‐angle Rutherford backscattering and transmission electron and optical microscopy measurements indicate that the mechanism for recrystallization is one of thermal solid‐phase regrowth from the underlying crystalline‐amorphous interface. No implant redistribution is observed.

Vertical integration: The monopsony case

Abstract: Backward integration is defined in order to improve the analysis of monopsony, and it is found that complete backward integration eliminates the efficiency losses from monopsonistic behavior Expanded input employment by the integrated monopsonist results in a greater final output at lower prices for consumers The author concludes that vertical integration by imperfectly competitive firms can be successfully modeled and analyzed if the concept of vertical integration, full and partial, is well defined and meaningful The welfare implications of integration on all participants in the industry can be considered and the incentives to integrate can be specified and examined 10 references

Thermally assisted flash annealing of silicon and germanium

Abstract: The radiant energy from high‐intensity xenon flash lamps can be used to anneal damage in semiconductors if the sample is moderately heated before and during the flash. The annealing takes place in air via the solid‐phase epitaxy process in <50 μsec and does not alter doping profiles or result in loss of volatile species.

FIR system modeling and identification in the presence of noise and with band-limited inputs

Abstract: System identification, that is, the modeling and identification of a system from knowledge of its input and output signals, is a subject that is of considerable importance in many areas of signal and data processing. Because of the diversity of applications, a number of different methods for system identification with different advantages and disadvantages have been described and used in the literature. In this paper we investigate the performance of three well-known system identification methods based on an FIR (finite impulse response) model of the system. The methods will be referred to in this paper as the least squares analysis (LSA) method, the least mean squares adaptation algorithm (LMS), and the short-time spectral analysis (SSA) procedure. Our particular interest in this paper concerns the performance of these algorithms in the presence of high noise levels and in situations where the input signal may be band-limited. Both white and nonwhite random noise signals as well as speech signals are used as test signals to measure the performance of each of the system identification techniques as a function of the signal-to-noise ratio of the systems output. Quantitative results in terms of an accuracy measure of system identification are presented and a simple analytical model is used to explain the measured results.

Ohmic contacts produced by laser‐annealing Te‐implanted GaAs

Abstract: We report the formation of Ohmic contacts to high‐dose (∼1016 cm−2) Te‐implanted n‐type GaAs annealed with a Q‐switched Nd : YAG laser. The annealing results in a Te concentration greater than 10 times the equilibrium solubility and the formation of free Ga at the surface. Ohmic contacts of specific contact resistance rc≃2×10−5 Ω cm2 were obtained by first removing the surface Ga by an HCl etch and then backsputtering to remove 50 A of GaAs, thereby exposing a surface of high Te concentration.

A NEW RESONANT ELLIPSOMETRIC TECHNIQUE FOR CHARACTERIZING THE INTERFACE BETWEEN GaAs AND ITS PLASMA-GROWN OXIDE.

Abstract: At certain wavelengths, depending on the thickness of a thin transparent dielectric layer on an absorbing substrate, a standing‐wave condition can be produced that efficiently couples the S wave to the substrate, simulating a cavity resonance in the dielectric and maximizing the complex reflectance ratio. Under these conditions high sensitivity is obtained to the nature of the interface between the dielectric and the substrate. We illustrate the method by applying it to plasma‐oxidized GaAs samples using scanning ellipsometry from 1.5 to 5.6 eV. As‐grown samples exhibit a composite transition layer at the interface consisting of a mixture of oxide, unoxidized GaAs, and elemental As. A crystalline As layer is formed at the interface by annealing in N2 at 550 °C.

Photocurrent spectroscopy of semiconductor electrodes in liquid junction solar cells

Abstract: Photocurrent spectra obtained by a two-beam (one pump--one probe) spectroscopic method on the semiconductor electrode of liquid junction solar cells can vary with the pump irradiance. In cells with n-type CdS, CdSe, CdTe, and GaAs photoanodes and chalogenide anion solutions this irradiance dependence results from and sensitively detects the presence of carrier recombination centers. With semiconductors showing no detectable recombination centers by this technique, cells with external solar to electrical conversion efficiencies of 8 to 9 percent have been made. Classical single beam photocurrent spectroscopy reveals that poor short-wavelength response in semiconductor liquid junction solar cells is due to surface or near surface recombination centers and resembles p-n junction solar cells in this respect. Lowered long-wavelength response is associated with shrinkage of the depletion region of imperfect and overdoped semiconductors.

Dose dependence in the laser annealing of arsenic-implanted silicon

Abstract: In the laser annealing of silicon by Nd : YAG laser irradiation a dose dependence of the annealing threshold and final impurity depth distribution has been observed. Impurity depth distributions and damage profiles observed by Rutherford backscattering are consistent with the notion of the formation of a thin liquid layer and subsequent regrowth of the crystal upon cooling. We conclude that the annealing behavior is very sensitive to the time of formation of the liquid layer during the laser pulse.

Quasiparticle and phonon propagation in bulk, superconducting lead

Abstract: We present a detailed account of our work on the propagation of quasiparticles and phonons in bulk, superconducting lead. Time-of-flight techniques combined with tunnel junction detection (for quasiparticle) and bolometer detection (for phonons) are used. A transition from quasiparticle diffusion (and ballistic phonon propagation) to diffusion in the combined gas of qasiparticles and phonons is observed as the temperature is increased. We give a theoretical description of the pulse propagation characteristics in the diffusive regimes. The theoretical line-shape fits to the data yield a measure of the quasiparticle recombination time and their number decay time as a function of temperature.

Facsimile transmission installation in particular for copying forms

Abstract: The present invention relates to a facsimile transmission installation adapted to allow rapid transmission of the contents of forms. In accordance with the invention, various types of blank forms are memorized and the transmission equipment includes a comparator connected to a memory and to an analysis circuit and allows the transmission of a facsimile signal which represents only the data added on the analyzed filled-in form and the reception equipment includes a text regenerator which operates from a transmitted facsimile signal and from a signal which comes from its memory.

Method of making an inductive circuit incorporated in a planar circuit support member

Abstract: A planar support member for an electric circuit, eg a printed circuit board, wherein at least a region of the support member includes magnetic material through at least a part of its thickness A magnetic circuit is made in this material by forming at least one opening through it The support member is then coated with insulative material and conductor paths are made on both faces of the support member by conventional techniques for such members These paths include a winding disposed around a core part of the magnetic circuit with alternate half turns being formed on opposite faces and interconnected by through plating The inductive circuit thus formed may constitute an inductor, a transformer or a relay

The effect of interface arsenic domains on the electrical properties of GaAs MOS structures

Abstract: Postgrowth annealing of plasma grown GaAs oxides in N2 and H2 result in very different electrical behaviors. By examining cross‐sectioned specimens of these oxides with transmission electron microscopy, and correlating the observed structure with electrical measurements, it is demonstrated that metallic As at the oxide‐semiconductor interface plays a significant role in determining the MOS characteristics.

A new method of fabricating gallium arsenide MOS devices

Abstract: A new method of fabricating gallium arsenide MOS devices with improved electrical properties is discussed. The device consists of a gallium arsenide substrate overlaid with a gallium arsenic oxide, a thin aluminum oxide, and a metallic contact. The oxide layers are fabricated using a plasma oxidizing process. These MOS devices show very high breakdown voltages (typically ≈±4×106 V/cm) and have low surface‐state densities (≈5×1010 cm−2).

Forward inclusive production spectrum of K/sub S/,. lambda. /sup 0/, Lambda-bar/sup 0/, and n in the collision of 200-GeV/c. pi. /sup -/, K/sup -/, p-bar, and rho on Be

Abstract: We have measured the forward production spectra of various neutral particles produced by ..pi../sup -/, K/sup -/, p-bar, and p at 200 GeV/c, and by ..pi../sup -/ at 290 GeV/c incident on a Be target. The salient features of these measurements are (1) copious production of K/sup 0//sub S/ at large Feynman x/sub L/ for incident ..pi../sup -/ and K/sup -/, (2) production of roughly equal fluxes of ..lambda../sup 0/ and ..lambda..-bar/sup 0/ for incident ..pi../sup -/, and (3) close similarity of the following spectra: ..pi../sup -/ ..-->.. n and K/sup -/ ..-->.. ..lambda../sup 0/; ..pi../sup -/ ..-->.. ..lambda../sup 0/, ..pi../sup -/ ..-->.. ..lambda..-bar/sup 0/; and p ..-->.. K/sup 0//sub S/; ..pi../sup 0/- ..-->.. K/sub s//sup 0/ and p ..-->.. ..lambda../sup 0/. The overall features of the various distributions seem to agree with the ideas of dimensional counting presented in the constituent-interchange model of quark collisions. Results are presented in terms of the invariant cross section Ed/sup 3/sigma (x/sub L/, P/sub perpendicular/ = 0)/dp/sup 3/ per Be nucleus for each inclusive reaction.