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  • 1
    Electronic Resource
    Electronic Resource
    Measurement of the energy decay rate for the first vibrational-excited-state in solid parahydrogen (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 930-932 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Energy decay rate of the first vibrational excited state for solid parahydrogen is measured from 4.8 K to 12 K. Measurements are carried out using the transient optothermal lensing spectroscopy with the vibrational excitations via the stimulated Raman scattering. The decay rate is measured to be 2.3×104 s−1 at 4.8 K, and it increases to 6.1×104 s−1 by raising the temperature to 12 K. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1379753
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  • 2
    Electronic Resource
    Electronic Resource
    Substituted cobalt phthalocyanine complexes as carriers for nitrite-sensitive electrodes
    Amsterdam : Elsevier
    Analytica Chimica Acta 297 (1994), S. 437-442 
    Details
    ISSN: 0003-2670
    Keywords: Carriers ; Ion selective electrodes ; Nitrite ; Phthalocyanines ; Poly(vinyl chloride) ; UV-Visible spectrophotometry
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0003-2670(94)00239-8
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  • 3
    Electronic Resource
    Electronic Resource
    Transient characteristics of AlxGa1−xN/GaN heterojunction field-effect transistors (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 4046-4048 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transient characteristics of drain-source current in response to picosecond pulsed gate-source voltages in AlxGa1−xN/GaN heterojunction field-effect transistors (HFETs) have been measured. It was found that the switching time constants were of the order of tens of picoseconds and depended strongly on the gate-source bias VGS as well as drain-source bias VDS. Slow transients caused by charge trapping effects such as those observed in AlGaAs/GaAs HFETs were absent in AlGaN/GaN HFETs. Our results suggested that the dependence of the effective electron mobility on the sheet density dictates the overall drain current transient characteristics as well as the device switching speed of AlGaN/GaN HFETs. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1332412
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  • 4
    Electronic Resource
    Electronic Resource
    GaN microdisk light emitting diodes (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 631-633 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Microdisk light-emitting diodes (μ-LEDs) with diameter of about 12 μm have been fabricated from InGaN/GaN quantum wells. Photolithographic patterning and inductively coupled plasma dry etching have been employed to fabricate these μ-LED devices. Device characteristics, such as the current–voltage characteristics, light output power, and electroluminescence (EL) spectra have been measured and compared with those of conventional broad-area LEDs. Our results showed that, for an identical area, the quantum efficiencies of μ-LED are enhanced over the conventional broad-area LEDs due to an enhanced current density and possibly microsize effects. The implications of our results on the design of future UV/blue microoptoelectronic devices are discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125841
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  • 5
    Electronic Resource
    Electronic Resource
    Persistent photoconductivity in Ga1−xInxNyAs1−y (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 1899-1901 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electrical properties of unintentionally doped p-type Ga0.95In0.05N0.013As0.987 quaternary alloys grown by metal–organic vapor-phase epitaxy have been investigated by Hall-effect and photoconductivity measurements. Persistent photoconductivity (PPC) has been observed in this material at temperatures T〈320 K. The PPC buildup and decay kinetics have been systematically measured at different temperatures and photoexcitation energies and formulated in the context of lattice-relaxed deep levels (or AX-like centers). The parameters which characterize the AX centers in GaInNAs, namely, the thermal and optical ionization energies, hole capture barrier, and the Stokes shift, have been determined. Our results indicate that AX-like deep levels strongly influence the electronic properties of the GaInNAs quaternary system. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124865
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  • 6
    Electronic Resource
    Electronic Resource
    Persistent photoconductivity in a two-dimensional electron gas system formed by an AlGaN/GaN heterostructure (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 1227-1230 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Persistent photoconductivity (PPC) effect associated with a two-dimensional electron gas (2DEG) in an AlGaN/GaN heterojunction device has been observed. As a consequence, the device was observed to be sensitive to light and the sensitivity was associated with a permanent photoinduced increase in the 2DEG carrier mobility and density. By formulating the PPC buildup and decay kinetics, we attributed the observed increase in the 2DEG carrier density and mobility to the photoionization of deep level impurities (DX like centers) in the AlGaN barrier material. In the PPC state, we were able to continuously vary the 2DEG carrier density in a single sample through photoexcitation and it has been found that the 2DEG carrier mobility increases almost linearly with the carrier density in the 2DEG channel. At 10 K, an electron mobility of 5800 cm2/V⋅s has been obtained in a PPC state. Implications of these observations on the device applications based on AlGaN/GaN heterojunctions have also been discussed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365893
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of persistent photoconductivity on the characteristic performance of an AlGaN/GaN heterostructure ultraviolet detector (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2868-2870 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photocurrent (PC) transient characteristics of an AlGaN/GaN heterostructure UV detector have been studied. We observed that the PC transients of the AlGaN/GaN heterostructure depended strongly on its initial conditions. Under a pulsed laser excitation, the PC responsivity, dark current level, and decay time constant all increased progressively with the number of successive excitation pulses and eventually saturated at constant values after about 30 pulsed laser exposures. Our results indicate that the observed PC transient characteristics are directly correlated with the effect of persistent photoconductivity in the two-dimensional electron gas region caused by deep level impurities and can have a significant influence on the performance of the UV photodetectors based on AlGaN/GaN heterostructures. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121485
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  • 8
    Electronic Resource
    Electronic Resource
    Nature of Mg impurities in GaN (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 1474-1476 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Mg doped GaN epilayers grown by reactive molecular beam epitaxy (MBE) exhibit clear persistent photoconductivity (PPC) whose manifestation has been used to probe the nature of Mg impurities in GaN. PPC buildup and decay transients and the dependence of the PPC decay time constant on the PPC buildup time have been systematically measured and formulated in the context of lattice relaxed Mg impurities (or AX centers). Our results have demonstrated that there is an energy barrier of about 129 meV which prevents free hole capture by ionized Mg impurities and that there is a lattice relaxation associated with Mg impurities in GaN. We also present a detailed comparison for Mg impurities in p-type GaN epilayers grown by MBE (hydrogen-free) and metalorganic chemical deposition (hydrogen rich). © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116912
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  • 9
    Electronic Resource
    Electronic Resource
    Excitonic recombination in GaN grown by molecular beam epitaxy (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3387-3389 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Time-resolved photoluminescence has been employed to probe the free-excitonic transitions and their dynamic processes in GaN grown by molecular beam epitaxy (MBE). The exciton photoluminescence spectral line shape, quantum yield, and recombination lifetimes have been measured at different excitation intensities and temperatures, from which the binding energy of an exciton, the energy band gap, and the free-exciton radiative recombination lifetimes of GaN grown by MBE have been obtained. Our results have demonstrated the superior crystalline quality as well as ultrahigh purity of the investigated sample, implying a new major breakthrough in MBE growth technologies for GaN. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114902
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  • 10
    Electronic Resource
    Electronic Resource
    Growth characteristics of γ-(Fe,Cr)"3C eutectic during unidirectional solidification
    Amsterdam : Elsevier
    Journal of Crystal Growth 133 (1993), S. 175-180 
    Details
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0022-0248(93)90118-G
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