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  • 1
    Electronic Resource
    Electronic Resource
    Carrier-density dependence of the photoluminescence lifetimes in ZnCdSe/ZnSSe quantum wells at room temperature (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 3359-3361 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence lifetimes have been measured at room temperature as a function of carrier density in ZnCdSe/ZnSSe quantum wells. We show that, at low carrier density (5×109–5×1010 cm−2), nonradiative recombination dominates, while radiative recombination becomes more dominant as the carrier density is increased from 5×1010 to 5×1011 cm−2. Above ∼5×1011 cm−2, band filling effects are shown to produce a saturation of the lifetimes. A simple rate equation model approach can be used to describe the carrier density dependence of the photoluminescence decay data obtained on a wide range of samples. A representative band-to-band recombination coefficient of 8×10−4 cm2 s−1 and a Shockley–Read–Hall rate of 7.3×107 s−1 were determined for one of the better samples studied. We believe that the excellent quality of our samples has allowed for the radiative recombination coefficient to be characterized accurately at room temperature. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123344
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  • 2
    Electronic Resource
    Electronic Resource
    Calculation of gain-current characteristics in ZnCdSe-ZnSe quantum well structures including many body effects (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3780-3782 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The gain-spontaneous recombination characteristics have been calculated for a 40 A(ring) Zn0.8Cd0.2Se-ZnSe quantum well including many body effects. We examine the effect of the inclusion of the Coulomb enhancement on the gain spectra and the gain-current relationship. We show that, in the absence of the Coulomb enhancement, the threshold current density of a 340 μm 40 A(ring) Zn0.8Cd0.2Se-ZnSe quantum well laser is underestimated by approximately 40% and the lasing wavelength overestimated by 4 nm. Our calculation of the scattering lifetime for the first electron-heavy hole transition gives a lifetime varying between 29 and 37 fs, and shows that the carrier-phonon scattering mechanism in II-VI quantum wells is more dominant than in III-V materials. We also comment on the effect the neglect of Coulomb enhancement has on the calculation of leakage currents in a laser at threshold. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115381
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  • 3
    Electronic Resource
    Electronic Resource
    Defect annealing in a II–VI laser diode structure under intense optical excitation (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 194-196 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Defect annealing under intense pulsed optical excitation has been observed in a II–VI laser diode structure at room temperature. More than one order of magnitude increase in photoluminescence intensity has been obtained when the annealed area is probed at low excitation intensity. High-resolution confocal photoluminescence images of the annealed region do not show any sign of degradation. Together, these results suggest that an initial density of intrinsic point defects present within the active region can be removed by the optical annealing. Recombination-enhanced defect reactions in the vicinity of the point defects are responsible for this nonthermal annealing effect. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120682
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  • 4
    Electronic Resource
    Electronic Resource
    Optical measurement of the ambipolar diffusion length in a ZnCdSe–ZnSe single quantum well (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 536-538 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a straightforward technique for the measurement of carrier diffusion in semiconductors. Using an optical microscope we can spatially image luminescence with a resolution of ∼500 nm. We measured the ambipolar diffusion length in a Zn0.75Cd0.25Se–ZnSe single quantum well by fitting the spatially resolved luminescence profile with the solution of the two-dimensional diffusion equation. The ambipolar diffusion length was found to be 498 nm at a carrier density of ∼1×1018 cm−3 and we deduce an ambipolar diffusion constant of 1.7 cm2 s−1. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364094
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  • 5
    Electronic Resource
    Electronic Resource
    Photoperiod and Androgens Act Independently to Induce Spinal Nucleus of the Bulbocavernosus Neuromuscular Plasticity in the Siberian Hamster, Phodopus sungorus (2002)
    Oxford, UK : Blackwell Science, Ltd
    Journal of neuroendocrinology 14 (2002), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In the Siberian hamster, Phodopus sungorus, short-day photoperiods induce the winter phenotype, which in males includes a decrease in the production of androgens and changes in physiology to inhibit reproduction. Motoneurones of the spinal nucleus of the bulbocavernosus (SNB) and their target muscles, the bulbocavernosus and the levator ani, a neuromuscular system involved in male copulation, also display seasonal plasticity in P. sungorus. It is not known whether the plasticity seen in the SNB system of gonadally intact hamsters is due to the effects of photoperiod per se, or to the photoperiod-induced changes in androgen production. To answer this question, we castrated adult male hamsters from long days and then implanted them with capsules containing either testosterone or blanks. Half of the hamsters from each hormone condition were moved into short photoperiod (8 : 16 h light/dark cycle) while the rest were maintained under long-day conditions (15 : 9 h light/dark cycle). After 15 weeks, many measures of the SNB system, such as somata size and weight of target muscles, responded only to androgen, not to photoperiod. However, there were effects of photoperiod on the neuromuscular junctions (NMJs) that were independent of androgen status. For example, the number of synaptic zones per NMJ and the area of the NMJs were significantly increased by short days and/or testosterone treatment. The two factors exerted an additive, rather than an interactive, effect on these measures. Another striated muscle, the extensor digitorum longus, which is present in both sexes and plays no specialized role in reproduction, displayed neither an effect of androgen nor of photoperiod on fibre size or NMJ structure. These results suggest that, in addition to androgenic effects on SNB plasticity, there is also an androgen-independent effect of photoperiod on the SNB neuromuscular system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0007-1331.2002.00791.x
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  • 6
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    Quantitative measurement of electron number in nanosecond and picosecond laser-induced air breakdown (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-05-06
    Description: Here we present quantitative measurements of total electron numbers in laser-induced air breakdown at pressures ranging from atmospheric to 40 bar g by 10 ns and 100 ps laser pulses. A quantifiable definition for the laser-induced breakdown threshold is identified by a sharp increase in the measurable total electron numbers via dielectric-calibrated coherent microwave scattering. For the 10 ns laser pulse, the threshold of laser-induced breakdown in atmospheric air is defined as the total electron number of ∼10 6 . This breakdown threshold decreases with an increase of pressure and laser photon energy (shorter wavelength), which is consistent with the theory of initial multiphoton ionization and subsequent avalanche processes. For the 100 ps laser pulse cases, a clear threshold is not present and only marginal pressure effects can be observed, which is due to the short pulse duration leading to stronger multiphoton ionization and minimal collisional avalanche ionization.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics (AIP)
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