Showing papers by "Alcatel-Lucent published in 1981"

Explosive crystallization of amorphous germanium

Abstract: We have obtained experimental confirmation of the prediction that explosive crystallization of amorphous germanium proceeds via an intermediate melting step.

Hydrogen plasma etching of GaAs oxide

Abstract: Hydrogen plasma has been used to etch native‐grown GaAs oxide on GaAs substrates. It is found that the rate of etching increases with gas pressure (in the range 10–300 μ) and the rf power (in the range 10–400 W) of the discharge. A typical etch rate of ≊20 A/sec can be easily achieved. The selectivity (determined by scanning electron microscopy) of the oxide etch over the substrate is ≊2. An etch mechanism is proposed, and the use of hydrogen plasma for surface preparation of GaAs and the etching of oxides on other semiconductor materials will be discussed.

A high gain In0.53Ga0.47As/InP avalanche photodiode with no tunneling leakage current

Abstract: We have fabricated high quantum efficiency, high‐gain (≊5500) avalanche photodiodes with long‐wavelength sensitivity up to λ = 1.7 μm. The primary dark current density at breakdown is JPR⩽8×10−5 A/cm2 with no evidence for tunneling leakage prior to avalanche. To fabricate avalanche photodiodes with no tunneling leakage and high photoresponse at breakdown, we find that the total number of fixed charges in the n‐InP layer must lie in the range of 2×1012 cm−2⩽σB⩽3×1012 cm−2.

Security method and device for communicating confidential data via an intermediate stage

Abstract: The invention relates to a method and devices allowing exchange of data between authorized bearers of crediting means (1) to be identified, approved and possibly coded and to remote centralized processing machines (3) via specific terminal units (2). The data produced by a bearer of a crediting means (1) after connection of said means (1) to a terminal unit (2) and sending of the identity of said means (1) are approved by a logic generation unit (15) of the means (1) from an individualization code and from transaction data. The invention applies to the exchange of data in an insecure environment and more particularly to bank credit card systems.

Boundary‐layer model of field effects in a bistable liquid‐crystal geometry

Abstract: Electric‐field‐induced switching between equilibrium configurations in certain bistable liquid‐crystal geometries is governed by the motion of disclinations, propelled by elastic distortions of the equilibrium states subjected to applied fields. In this paper and the next (paper II), we describe the distortions and energies of bistable planar horizontal and vertical states, and nonplanar twist states in a tilted geometry, using exact numerical solutions of the equilibrium equations as well as a ’’boundary‐layer’’ approximation in the high‐field limit. The calculations illustrate the manner in which the distortions become concentrated in boundary layers within a coherence length from the surface, and show the convergence of the planar and nonplanar vertical states at relatively low fields. Implications for the switching mechanism are discussed. In paper II, the boundary‐layer model is used to describe the forces governing the movement of disclinations in bistable switching, producing a quantitative descrip...

Reactive ion etching of LiNbO3

Abstract: We describe the reactive ion etching of LiNbO3 in gas mixtures containing CCl2F2, CF4, O2, and Ar The effects of gas composition and pressure, in the range 1–10‐μm total pressure are discussed Because it is possible to replicate fine features (∼2000 A) with control of etch profiles, we expect the process to be used for three‐dimensional patterning of LiNbO3 for electro‐optic and acoustic‐optic devices

Properties of aluminum epitaxial growth on GaAs

Abstract: The structural perfection and epitaxial growth process of Al films deposited by molecular beam epitaxy (MBE) on (100) GaAs substrates have been analyzed by transmission electron microscopy (TEM) and Rutherford backscattering analysis (RBS). Two epitaxial relationships between the Al film and (100) GaAs are observed. In general, deposition on As‐rich surfaces at room temperature and low deposition rates (200–750 A/h) lead to 〈110〉 oriented Al films. Higher deposition rates at room temperature yield a mixture of 〈110〉 and 〈100〉 oriented films or completely 〈100〉 oriented films at the higher deposition rates. On Ga‐rich surfaces, only 〈100〉 oriented Al films are observed. For both epitaxial orientations the misfit elastic strain at the interface is accommodated by misfit dislocations localized in the Al film for film thicknesses of ⩾ 600 A. Under these conditions the GaAs substrate at the interface is strain free and dislocation free. The presence of surface steps associated with surface reconstruction at the start of the epitaxial process is invoked to account for the existence of 〈110〉 oriented film growth on 〈100〉 substrates.

50−nm silicon structures fabricated with trilevel electron beam resist and reactive‐ion etching

Abstract: A trilevel electron beam resist has been used to make 25‐nm metal features on thick silicon substrates. Using this metal as a mask for reactive ion etching, silicon structures 0.33 μm deep have been fabricated. The resist consists of a thin upper layer of polymethylmethacrylate (PMMA), a middle layer of Ge, and a lower layer of co‐polymer of methylmethacrylate and methacrylic acid, P(MMA/MAA). High‐resolution patterns are written in the upper resist layer and are transferred to the lower layers by reactive‐ion etching. Completed resist stencils have 300‐nm high walls with near‐vertical profiles and are suitable for liftoff processing.

Electron impact ionization cross section of metastable N2(A Σ+u)

Abstract: The nondissociative electron impact ionization cross section of the metastable N2(A 3Σ+u) state is measured from threshold to 240 eV. Rising from an appearance potential of 10.1±0.6 eV, the cross section peaks at about 40 eV with a value of (1.14±0.36)×10−16 cm2. These values are extracted from the apparent ionization cross section of an N2 beam composed of ∼50% N2(A 3Σ+u) and ∼50% N2(X 1Σ+g). This mixed state beam is formed by charge transfer neutralization of a 1 keV N+2 beam with NO. The N2(A 3Σ+u) cross section is normalized by measuring it relative to the ionization of a ground state N2 beam formed by charge transfer neutralization of N+2 with N2.

Protein influences on porphyrin structure in cytochrome c: evidence from Raman difference spectroscopy

Abstract: To probe the details of protein heme interactions, a Raman difference spectroscopic technique has been developed which allows reliable detection of very small, approx. =0.01 cm/sup -1/, frequency differences. When this technique is applied to heme proteins, structural differences in the protein which perturb the porphyrin macrocycle may be examined by obtaining Raman difference data on the porphyrin vibrational modes which are strongly enhanced in the Raman spectrum produced with visible laser excitation. Reported are Raman difference spectroscopic data on cytochromes c from 24 species. The differences in the Raman spectrum of the porphyrin between the cytochromes c of any two species are small, confirming that all of the cytochromes we have examined have the same ''cytochrome fold''. However, many small (0.02-2cm/sup -1/) but systematic differences were detected which indicate structural differences among these proteins. These differences could be classified into three different groups and interpreted in terms of different types of structural variations resulting from specific differences in the amino acid sequences.(JMT)

Demonstration of nitrogen coordination in metal--bleomycin complexes by electron spin--echo envelope spectroscopy.

Abstract: We have studied the Cu(II), Co(II), and Fe(III) complexes of the antineoplastic drug bleomycin by using electron spin--echo envelope spectroscopy. For all three complexes, nitrogen coordination of the metal ions is demonstrated. For the Cu(II)-- and Co(II)--drug complexes, we have been able to identify imidazole as a metal ligand.

Effect of Tetramethylammonium Ion on the Helix-to-Coil Transition of Poly(deoxyadenylylthymidine): A Nuclear Magnetic Resonance and Calorimetric Investigation

Abstract: Differential scanning calorimetry, temperature-dependent NMR, and UV spectroscopy are used to investigate the helix-to-coil transition of poly(deoxyadenylylthymidine) [poly(dA-dT)] in 1 M NaCl and 1 M Me4NCl (tetramethylammonium chloride) All three methods reveal that the polymer has a melting temperature, tm, that is approximately 6 degree C higher in 1 M Me4NCl than in 1 M NaCl The NMR data show that this increased stability does not result from fundamental changes in base stacking or base pairing in going from 1 M NaCl to 1 M Me4NCl Consistent with this observation, the calorimetric measurements yield essentially equal enthalpies for the helix-to-coil transition under the two salt conditions (68 kcal per base pair in 1 M NaCl and 70 kcal per base pair in M Me4NCl) Analysis of the shapes of the calorimetric curves shows that the transition is more cooperative in Me4NCl than in NaCl Comparison of the calorimetric and van't Hoff enthalpies allows specification of the size of the cooperative unit: 27 base pairs in 1 M NaCl and 32 base pairs in 1 M Me4NCl The NMR data reveal that the major Me4NCl-induced structural alterations (relative to NaCl) are a change in one glycosidic torison angle and a partial resolution of the two phosphates The calorimetric experiments indicate that in the absence of fortuitous compensation these conformational changes are not accompanied by a significant enthalpy effect On the basis of these data, we suggest that in 1 M NaCl poly(dA-dT) assumes predominantly a B-DNA-like conformation where the symmetry repeat occurs every base pair By contrast, in 1 M Me4NCl the predominant conformation exhibits a dinucleotide repeat consistent with a right-handed alternating B-DNA structure

Postal meter using microcomputer scanning of encoding switches for simultaneous setting of electronic accounting & mechanical printing systems

Abstract: An entire electronic accounting and controlling system for a franking machine is mounted on two connected printed circuit boards, one along the top of the machine and the other along one side of the machine within the machine casing. The top board carries four rotary encoding switches and press button switches which are scanned by signals from a microcomputer on the side board passing to a binary counter controlling a binary to decimal decoder to send multiplexed signals to the switches enabling the rotary switches to send four pairs of five-bit words along ten scanning lines to the microcomputer which delivers equivalent eight-bit error immune signals to duplicate non-volatile memories. The press button switches send signals along the scanning lines to enable a display module on the top board to display decimal digits according to the information stored in the memories. A printing drum is set mechanically simultaneously with the rotary switches. When a sealed door in the casing is opened a switch is automatically actuated to change over from customer mode to Post Office mode.

Apparatus for chemically activated deposition in a plasma

Abstract: An apparatus for chemically activated depositing in a plasma. Said apparatus includes a chamber (1) in which a vacuum is maintained, said chamber being closed by means of a top plate (2) and a bottom plate (3) which are removable. Said apparatus further includes a substrate support (5) disposed about said axis, a reactive gas distributor manifold and means (4) for setting up a plasma inside said chamber (1). Said manifold (8) has two circular end portions (9,10) interconnected by pipes (11) in which gas outlet orifices are provided; said pipes being rotatable at a uniform speed about the axis of the chamber inside said substrate support; said support being of polygonal cross-section and constituted by rectangular longitudinally extending facets on which the substrates (7) are deposited. The invention is used to deposit chromium, silicon, aluminium and the like.

The Propagation of disclinations in bistable switching

Abstract: The boundary‐layer model is used to calculate the energy density of the forces that govern the movement‐of‐strength 1/2 disclinations in a bistable tilted liquid‐crystal geometry during switching. The distortions of the bistable states and the disclinations separating them are studied. The mobility is calculated for vertical and transverse applied fields and compared with experimental data, showing good agreement especially at high fields. Implications about a switching mechanism are discussed.

Efficiency losses from carrier‐type inhomogeneity in tungsten diselenide photoelectrodes

Abstract: The coexistence of macroscopic p‐ and n‐type domains in nominally smooth, single‐crystal tungsten diselenide photoelectrodes leads to substantial efficiency losses in these crystals. The presence of such regions is demonstrated by rotating‐disk electrode experiments, Seebeck coefficient measurements, and in situ topographic photogenerated carrier‐collection analysis with a scanning laser spot. These results indicate the importance of controlling growth parameters to yield homogeneously doped crystals to achieve maximum solar conversion efficiencies.

Individualized portable object such as a credit card

Abstract: The object requires a would-be user to supply an authorization code within a predetermined number of attempts, otherwise the object is invalidated. The object has at least one memory (1) in which the results of attempts at use are stored in permanent binary form. The object also includes memory write means (3) and discriminator means (9). These are arranged to distinguish between an un-interrupted sequence of said predetermined number of failed attempts (in which case the object is invalidated) and a sequence of failed attempts which is interrupted by at least one successful attempt.

Hadron-production mechanisms in antineutrino-proton charged-current interactions

Abstract: In this paper we present results on hadronic production in antineutrino-proton interactions. The data sample, which consists of 2033 charged-current events with antineutrino energy above 5 GeV, comes from exposures of the 15-foot hydrogen bubble chamber to the Fermilab broad-band antineutrino beam. The results are discussed in terms of both their exclusive-channel components and the deep-inelastic part of the data, for which the total hadronic mass W and the lepton four-momentum transfer Q/sup 2/ are large. The current-quark fragmentation shows properties in good agreement with the simple quark-parton model. In particular, the data show no evidence for scaling violations or breakdown of the factorization hypothesis when the selections appropriate to obtaining the current-quark fragments are used. The jetlike features of the events and the energy and charge correlations in the quark fragmentation region are in reasonable agreement with the standard jet model of Field and Feynman. However, these features and the transverse-momentum properties of the current-quark fragments also follow phase-space predictions. The characteristics of the spectator-diquark (target fragmentation) system are presented. These features are compared to those of the current-quark system and to some predictions of quark-fusion models for proton fragmentation.

Gas bleed cock

Abstract: A cock for low-pressure bleeding of a gas from a gaseous mixture, said cock having a body (1) with an inlet (12) and a pumping outlet (13) for the mixture and a bleed outlet orifice (15), and a valve (2) which co-operates with the valve body and is situated between said orifice and the inlet, wherein the valve includes a semi-permeable membrane with a first surface (6A) which communicates with said inlet and a second surface (6) which communicates with said bleed orifice, the valve assuming a first position in which it allows the mixture to pass directly from the inlet towards the bleed orifice when the pressure of the mixture is lower than a given pressure, and a second position in which it closes the bleed orifice when the pressure of the mixture is higher than said given pressure, the gas to be bled off then passing through said permeable membrane.

Range profiles of low-energy (100 to 1500 eV) implanted 3He and 4He atoms in tungsten II. Analysis and discussion

Abstract: The identifiable sources of possible systematic errors in the measurement of the mean range (x) and the straggling (Δx) of the 3He and 4He range profiles, reported on in the previous paper (Amano, Wagner and Seidman 1981, Part I) are modelled mathematically and the resulting expressions numerically evaluated. The evaluations show that these possible sources of systematic errors are not of significant magnitude to affect the range parameters x and Δx. The role of the transfer of energy, either indirectly or directly, from the incoming beam of helium ions to those helium atoms that had already been implanted is also considered as a possible source of systematic error. It is shown that there is a possibility of radiation-induced diffusion or the simple displacement of helium atoms—as a result of helium-helium collisions—at an implantation energy of 100 eV and a fluence of 4 × 1015 cm−2; however, the magnitude of this effect is probably not large enough to have a major effect on the detailed shape of...

Resonant photoemission in CeS and CeP

Abstract: Direct and resonant photoemission experiments on CeS and CeP show that the 4f level lies in a band gap in CeS but overlaps the valence band in CeP. At the 4d→4f resonance threshold the 4f level and the valence-band emission features are found to be weakly coupled in CeS and strongly coupled in CeP.