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  • Electronic Resource  (25)
  • 1995-1999  (15)
  • 1985-1989  (10)
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  • Electronic Resource  (25)
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  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report measurements of the pressure dependence of the mobility of a two-dimensional electron gas in GaInAs/InP single and multiple quantum well systems and at a single heterojunction. The mobility dependence on both carrier density and effective mass is derived and shown to be the same in each system. Current theories of polar optic phonon scattering do not explain the mobility variation with carrier density but can describe the effective mass dependence.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 2342-2359 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The pressure dependence of the electron Hall mobility has been measured in a wide variety of InP and GaAs samples. The results, analyzed by a number of techniques, indicate that, in general, very good agreement can be obtained between theory and experiment for pure material at temperatures where ionized impurity scattering is unimportant. When heavily doped samples of liquid-phase epitaxy (LPE) GaAs and vapor-phase epitaxy (VPE) InP were measured it was not possible to predict the experimental pressure dependence of the mobility using the Brooks–Herring theory of scattering from ionized impurities. The possibility of inaccuracies in analysis have been reduced by using an iterative solution of the Boltzmann equation, phase shift calculations, and also Moore's analysis [Phys. Rev. 160, 618 (1967)] for dressing and multi-ion corrections. However, these proved to be inadequate and we obtain the best agreement with experiment using the theory of Yanchev et al. [J. Phys. C 12, L765 (1979)] for scattering from a correlated distribution of impurities. The important effects of impurity correlation have been substantiated by studying samples of GaAs grown by molecular-beam epitaxy (MBE) and bulk GaAs subjected to neutron transmutation doping. The inability of impurities to correlate in such material is demonstrated by the close agreement between Brooks–Herring theory and experiment for these samples. When correlation scattering is taken into account, it becomes possible to explain the observed mobilities in heavily doped materials without having to always postulate autocompensation, as has been done by other authors.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 3448-3450 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the linear losses in a GaAs/AlGaAs double-heterostructure laser as a function of applied hydrostatic pressure. The nonradiative lifetime increases by a factor 2.5 from zero to 7.6 kbar, and if this is due to recombination via a deep state, then the rate-limiting capture cross section decreases with pressure, suggesting capture by multiphonon emission. We find that it is necessary to postulate the existence of other nonlinear losses at threshold to account for the increase in threshold current with pressure measured on the same structure. Carrier transfer to higher conduction-band minima in the active or cladding regions are suggested as possible mechanisms.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 2031-2034 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Laser chemical vapor deposition of patterned iron deposits on silica glass has been carried out using an Ar ion laser-driven dissociation of iron pentacarbonyl vapor. The structure of the deposited films has been studied using optical, electron, and scanning Auger microscopic techniques. Extensive iron silicate formation is observed at the iron-glass interface and 50-μm periodic ripples are formed in the delineated deposits. The origin of the periodic structure is discussed with reference to the available analytical data and observations from related laser processing studies.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 2640-2645 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Room-temperature Hall mobility as a function of pressure (0–8 kbar) has been measured for high-purity liquid-phase-epitaxy-grown Ga1−xAlxAs layers. GaAs-like band structure of low-composition alloys has also been converted to Si-like band structure at high pressures and the Hall mobility measured as a function of temperature (77(approximately-less-than)T(approximately-less-than)300 °K) with crystals locked under constant pressures. The data have been analyzed to identify and distinguish the presence of space charge and alloy scatterings both characterized by mobilities limited by T−1/2. The space charge scattering has been found to be absent in all the crystals studied except x=0.047. The alloy scattering potential for electrons in the Γ minimum has been shown to depend on the alloy composition with a maximum value of 1.56 eV at x=0.19. For electrons in the X minima, this potential has been found to be independent of composition with a value of only 0.4 eV.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2876-2878 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The avalanche breakdown voltage (Vb) has been measured in a range of bulk AlxGa1−xAs alloys and Al0.3Ga0.7As/GaAs multilayer structures. The bulk alloys show a linear dependence of Vb on x up to at least x=0.6. Multilayers with thin (≤100 A(ring)) dimensions follow this trend, with Vb being determined by the average Al fraction of the multilayer "pseudoalloy''. For thicker (≥500 A(ring)) layers Vb tends to a mean of the bulk values of the layers. The transition from pseudoalloy to bulklike behavior is interpreted in terms of the momentum and energy relaxation lengths, estimated for bulk GaAs using a Monte Carlo solution of the semiclassical transport equation. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 2904-2906 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show theoretically how the quantum-confined Stark effect (QCSE) shifts of the E1–HH1 and E1–LH1 energy transitions can be engineered to be closely matched over the entire range of applied fields up to ±100 kV/cm using structures containing more than one strained-layer composition within each well. In contrast, conventional quantum wells that contain a single uniform composition within each well can at best have the energy levels for the HH1 and LH1 states matched at only one field value. Furthermore, we show how the TE and TM absorption spectra are modified using multistrain-stepped structures leading to improved polarization-insensitive QCSE modulators. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3546-3548 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By measuring the spontaneous emission from strained and unstrained 1.5 μm InGaAs quantum well lasers as a function of temperature we deduce the temperature dependence of the radiative current density at threshold corresponds to a characteristic temperature T0≈300 K, close to that expected from theory, whereas T0 of the threshold current is around 60 K. We conclude from our analysis that the large temperature dependence of long wavelength lasers is due to Auger recombination. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3304-3306 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the avalanche breakdown voltage (Vb) in GaAs p-i-n diodes as a function of hydrostatic pressure up to 14 kbar. The pressure coefficient of Vb was small and opposite in sign compared to that of the band gap. A lucky-drift calculation of Vb including the effects of pressure on both the phonon scattering and ionization rates showed that the ionization threshold energy does not scale with the band gap. Instead, the effective threshold scales with an average of the energies of the Γ, X, and L conduction-band minima. This is direct evidence that pair production yields final electron states distributed between conduction-band valleys. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 44 (1989), S. 0 
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The time to safe return of neuromuscular function after atracurium 0.3 mg/kg intravenously was assessed in 24 patients in whom anaesthesia was maintained with halothane 0.5%. Safe reversal (recovery to a T4 ratio 〉 05), after this dose of atracurium, could only be reliably and rapidly (〈 2 minutes) achieved with edrophonium if a period greater than 30 minutes elapsed since administration of the relaxant. This coincides with the appearance of four recognisable twitches if a train-of-four pattern of nerve stimulation is used. Thus, if no monitoring equipment is available, at least half-an-hour should elapse after administration of atracurium in a moderate dose (e.g. 0.3 mg/kg) before rapid and reliable reversal can be anticipated. Four twitches in a train-of-four should be recognisable, if a nerve stimulator is available.
    Type of Medium: Electronic Resource
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