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  • 1
    Electronic Resource
    Electronic Resource
    Intense visible light emission from fullerene-doped silica aerogel (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 2801-2803 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report that fullerenes (C60/C70) can be uniformly encased in silica aerogel by sol-gel process together with supercritical drying technique. Intense visible light emission (2.26 eV) is observable with the naked eye from the composite under an Ar+ laser (488 nm) excitation at room temperature. The luminescent intensity is found to increase strongly with low doping of fullerenes (0.05 mol %) and then to decrease while the peak is red shifted, and finally quenched upon heavy doping (up to 2.5 mol %). This effect is consistent with the behavior of the fullerenes entrapped in the micropores linked by the silica networks resulting in the quantum confinement effect which then produce emission far above the interband gap of C60/C70. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358685
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanisms of valley currents in InAs/AlSb/GaSb resonant interband tunneling diodes (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 6220-6223 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Several possible contributions to the valley currents in InAs/AlSb/GaSb resonant interband tunneling diodes are analyzed. A theoretical model proposes that the field-assisted thermionic hole emission is the main valley leakage mechanism at high temperature and the Fowler–Nordheim hole tunneling is the dominant leakage path at low temperature and high bias. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360568
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  • 3
    Electronic Resource
    Electronic Resource
    Three-dimensional model for cw laser-induced mode-mismatched dual-beam thermal lens spectrometry and time-resolved measurements of thin-film samples (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 3738-3748 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Conventional thermal lens spectrometry theory assumes that the sample is an infinite medium, and only the radial temperature rise and heat flow in the sample are considered. This approach is not suitable for thin-film samples. Considering the axial boundary conditions of the sample, a three-dimensional model for cw laser-induced mode-mismatched thermal lens spectrometry is presented. However, its mathematical expression is not so convenient as that of the conventional theory to deal with the experimental data. The model shows that, besides axial boundary conditions of the sample, the ratio of excitation laser spot size to the sample thickness ωe/l is a crucial parameter to minimize the axial heat flow. By choosing small ωe/l, it is possible for the conventional theory to describe the development of the thermal lens of a thin sample for a short duration. Experimental proofs for the theoretical prediction are made, and good agreements are achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356046
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  • 4
    Electronic Resource
    Electronic Resource
    Tamm states and donors at InAs/AlSb interfaces (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1576-1581 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Localized interface states, viz., generalized Tamm states, can be induced by an interfacial InSb bond in the InAs/AlSb heterojunction system, as confirmed by electronic structure calculations. The calculated energies of the interfacial Tamm states, however, are too low to account for the observed carrier concentrations in InAs quantum wells. Native defects capable of accounting for the observed carrier concentrations are identified, and their electronic structures calculated: AlSb in an AlSb layer is responsible for the semi-insulating character of thin InAs quantum wells and the n-type character of wide wells, and AsAl at an AlAs-like interface is responsible for the high values of electron concentration in the wells. The decrease of electron concentrations with temperature can be attributed to partial freezing of electrons into the shallow levels associated with ionized donors. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358910
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  • 5
    Electronic Resource
    Electronic Resource
    A model for cw laser induced mode-mismatched dual-beam thermal lens spectrometry based on probe beam profile image detection (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 700-708 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A model for cw laser induced mode-mismatched dual-beam thermal lens spectrometry using probe beam profile detection has been developed. This model exhibits the following behavior: after passing through the thermal lens the TEM00 Gaussian probe beam becomes the superposition of several Gaussian beams of different parameters. This model has a compact mathematical expression, for which experimental proofs are given. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360329
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  • 6
    Electronic Resource
    Electronic Resource
    Thermal-wave resonator cavity (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 4999-5005 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A thermal-wave resonant cavity was constructed using a thin aluminum foil wall as the intensity-modulated-laser-beam induced oscillator source opposite a pyroelectric polyvilidene fluoride wall acting as a signal transducer and cavity standing-wave-equivalent generator. It was shown that scanning the frequency of oscillation produces the fundamental and higher overtone resonant extrema albeit with increasingly attenuated amplitude—a characteristic of thermal-wave behavior. Experimentally, scanning the cavity length produced a sharp lock-in in-phase resonance with simple linewidth dependencies on oscillation (chopping) frequency and intracavity gas thermal diffusivity. The thermal diffusivity of air at 294 K was measured with three significant figure accuracy: 0.211±0.004 cm2/s. The novel resonator can be used as a high-resolution thermophysical property sensor of gaseous ambients. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146123
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  • 7
    Electronic Resource
    Electronic Resource
    Carrier transport in organic alloy light emitting diodes (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3891-3895 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present theoretical models and numerical results on the carrier transport mechanisms in single-layer organic alloy light emitting diodes. A typical organic alloy consists of a mixture of electron and hole transporting materials and is modeled by assigning individual conduction channels to each type of material. The sensitivity of the diode efficiency on several key parameters (alloy composition, energy level difference, contact barrier height, and traps, etc.) is studied. The results can be used to design structures to achieve balanced carrier injection and transport by properly adjusting these parameters. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372430
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  • 8
    Electronic Resource
    Electronic Resource
    Criteria for Si quantum-well luminescence (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 8458-8462 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Criteria are developed for selecting a barrier material XY such that Si/XY superlattices should emit light from their Si quantum wells. GaAs is such a material for [001] superlattices. In many such superlattices, substitutional N on a Si site will be a shallow donor, not a deep trap.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353419
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  • 9
    Electronic Resource
    Electronic Resource
    Remote n-type modulation doping of InAs quantum wells by "deep acceptors'' in AlSb (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 8313-8318 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Due to the fact that impurities normally change their doping characters when they undergo shallow to deep transitions or deep-to-false-valence transitions, a single defect, such as a cation on an Sb site, can explain all of the following facts for nonintentionally doped AlxGa1−xSb alloys and InAs/AlxGa1−xSb superlattices and quantum-well structures: (i) Bulk GaSb is p type; (ii) bulk AlSb is semi-insulating; (iii) InAs/AlSb superlattices with InAs quantum wells thicker than a critical thickness dc(x=1.0) are n type, where the InAs shallow–deep critical thickness function dc(x) is around (approximately-equal-to)100–(approximately-equal-to)150 A(ring) for 0.5〈x≤1.0 for InAs/AlxGa1−xSb superlattices; (iv) InAs/AlSb superlattices with InAs quantum wells thinner than dc(x=1.0) are semi-insulating. In addition, the theory predicts that Al0.5Ga0.5Sb and AlSb will be semi-insulating when nonintentionally doped, but can be converted to p type by the application of hydrostatic pressure P: P(approximately-greater-than)90 kbar and P(approximately-greater-than)150 kbar, respectively. These changes of doping character, which lie outside the conventional effective-mass theory, occur often in type-II band-alignment systems, such as InAs/AlxGa1−xSb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353450
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  • 10
    Electronic Resource
    Electronic Resource
    A radial finite model of thermal lens spectrometry and the influence of sample radius upon the validity of the radial infinite model (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5286-5288 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Conventional thermal lens models unrealistically assume that the sample has an infinite radius. Taking realistic radial sample boundary conditions into account, a cw laser-induced mode-mismatched dual-beam thermal lens model is presented. Comparison of these two kinds of models has been made, which gives the quantitatively necessary and sufficient condition for the validity of the radial-infinite treatment on the sample: The sample radius should be larger than 2.5 times both excitation beam and probe beam radii in the sample.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353761
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