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  • 1
    Electronic Resource
    Electronic Resource
    High-field electron transport for ellipsoidal multivalley band structure of silicon (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4700-4704 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-field electron-transport properties of bulk silicon are studied taking into account the multivalley band structure with ellipsoidal energy surface. A distribution function that takes into account the anisotropy introduced in electron motion by the high electric field is described. This puts some order in the otherwise completely random motion. The transition from linear to nonlinear behavior is obtained when the energy gained by an electron in traversing a mean free path is comparable to the thermal energy. The drift velocity is shown to be limited to the random thermal velocity for nondegenerate electrons and to the Fermi velocity for degenerate electrons. This indicates independence of the saturation velocity on momentum-randomizing scattering events which control the mobility. The emission of an optical phonon is significant when inelastic scattering length is comparable to the momentum randomizing mean free path. This further lowers the saturation velocity. When an electric field is applied along the 〈100(approximately-greater-than) direction in silicon, an intervalley transfer from valleys with lower mean free path to the ones with higher mean free path is obtained. When compared with the experimental data on silicon, an excellent agreement is obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352075
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  • 2
    Electronic Resource
    Electronic Resource
    Bubble formation and growth in organic light-emitting diodes composed of a polymeric emitter and a calcium cathode (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5712-5715 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The formation and growth of bubbles within dark spots in organic light-emitting diodes comprised of an electroluminescent polymer and a Ca–Ag cathode have been observed and studied. Our studies indicate that electric stress and pinholes are two important parameters affecting the formation of bubbles. More detailed analysis reveals the dependence of bubble area on the pinhole diameter. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1467395
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  • 3
    Electronic Resource
    Electronic Resource
    Buried heterostructure InGaAsP/InP strain-compensated multiple quantum well laser with a native-oxidized InAlAs current blocking layer (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 3803-3805 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An InAlAs native oxide is used to replace the p-n reverse-biased junction in a conventional buried heterostructure InP-based laser. This technique reduces the number of regrowth steps and eliminates leakage current under high-temperature operation. The InAlAs native oxide buried heterostructure (NOBH) laser with strain-compensated InGaAsP/InP multiple quantum well active layers has a threshold current of 5.6 mA, a slope efficiency of 0.23 mW/mA, and a linear power up to 22.5 mW with a HR-coated facet. It exhibits single transverse mode with lasing wavelength at 1.532 μm. A characteristic temperature (T0) of 50 K is obtained from the NOBH laser with a nonoptimized oxide layer width. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122899
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  • 4
    Electronic Resource
    Electronic Resource
    Photoreflectance study of Si-doped GaN grown by metal–organic chemical vapor deposition (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1890-1892 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Si-doped n-GaN films grown by metal–organic chemical vapor deposition were studied by photoreflectance (PR) spectroscopy. Based on the intense optical transitions observed in the room-temperature PR spectra, the energy positions of the near-band-edge transition for n-GaN samples with different Si-doping levels were determined through theoretical curve fitting under the weak-field approximation. Furthermore, based on the observed dependence of the redshift in the near-band-edge transition energy with the carrier concentration and the approach using the many-body theory, the band-gap renormalization coefficient for GaN was derived to be (2.4±0.5)×10−8 eV cm. This value was found to be nearly 35% larger than that for GaAs.© 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121217
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of electrical stress voltage on cathode degradation of organic light-emitting devices (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 976-979 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Our in situ experimental observations of the influence of electrical stress voltage on organic light-emitting device growth in dark spot areas are presented. We demonstrate the use of microsized silica particles to create uniformly sized defects on the protective layer. This is an efficient way to control the location and the number of dark spots. The growth in dark spot area was studied at different driving voltages from 0 up to 11 V. Dark field microscopy was used to monitor the dark spot size below the turn-on voltage. The bright field was used at or above the turn-on voltage. Our observations indicate that dark spot growth was strongly affected by the electrical stress voltage. A linear growth rate with respect to the voltage was observed with a fitting parameter better than 99.7% when the device is driven above the turn-on voltage. We interpret the dark spot growth in terms of the diffusion of moisture and oxygen accompanied by cathode layer chemical and physical changes. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1376669
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  • 6
    Electronic Resource
    Electronic Resource
    Improved Mg-doped GaN films grown over a multilayered buffer (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1772-1774 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Mg-doped p-GaN films have been grown on sapphire substrate with a multilayered buffer (MLB) by metalorganic chemical vapor deposition and characterized by photoluminescence spectroscopy. The MLB consists of GaN/AlxGa1−xN (0〈x≤1) superlattice-like layer structures although the material combination as well as the periodicity and uniformity in layer thickness and composition are not essential issues for constituting a MLB. It was found that the p-GaN films grown on MLBs gave much stronger optical emission than those grown on conventional GaN or AlxGa1−xN (0〈x≤1) single-layer buffer or GaN/AlxGa1−xN double-layer buffer under identical reactor configuration. This fact indicates that, by using the newly-developed MLB, the crystalline quality of group-III nitride-based-semiconductor epitaxial layers can be significantly improved. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122277
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  • 7
    Electronic Resource
    Electronic Resource
    Enhanced optical emission from GaN films grown on a silicon substrate (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 1984-1986 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaN films have been grown on a silicon-(001) substrate with specially designed composite intermediate layers consisting of an ultrathin amorphous silicon layer and a GaN/AlxGa1−xN (x=0.2) multilayered buffer by metal-organic chemical vapor deposition and characterized by photoluminescence and x-ray diffraction spectroscopy. It was found that the GaN films grown on the composite intermediate layers gave comparable or slightly stronger optical emission than those grown on a sapphire substrate under an identical reactor configuration. Moreover, the full-width at half-maximum for the GaN band-edge-related emission is 40 meV at room temperature. This fact indicates that by using the proposed composite intermediate layers, the crystalline quality of GaN-based nitride grown on a silicon substrate can be significantly improved. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123721
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  • 8
    Electronic Resource
    Electronic Resource
    Optical property of a novel (111)-oriented quantum structure (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1840-1842 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A novel hetero tensile-unstrained-tensile-unstrained-tensile (t-u-t-u-t) quantum structure, which consists of multiple quantum wells in the unstrained (u) regions, lattice matched to a (111)-oriented substrate, and sandwiched between tensile-strained epitaxial layers (t), is proposed. The energy band configuration modified by the strain-induced piezoelectric field and the distribution of the built-in internal electric field within this hetero t-u-t-u-t quantum structure were theoretically deduced and found to be consistent with the experimental results. It was demonstrated that some nonlinear optical properties such as the energy blue shift observed in the excitation-power-dependent photoluminescence spectra are strongly dependent on the distribution of the strain-induced built-in electric field within this quantum structure and quite comparable to the analogous values for the existing quantum structures. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119416
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  • 9
    Electronic Resource
    Electronic Resource
    Stabilization of electrode migration in polymer electroluminescent devices (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 1119-1121 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A thin 3-nm-thick parylene layer is deposited by chemical vapor deposition at room temperature on the indium tin oxide (ITO) coated glass substrate to form a bilayer anode of an organic light emitting diode. The parylene layer forms a conformal film to cover the spikes present in the ITO film. This parylene film presents a smoother surface to the subsequent organic layers. The parylene film not only reduces the occurrence of dark spots, acting as a barrier for oxygen diffusion from either the ITO or from the atmosphere and stabilizing the migration of the electrodes during electrical stress, but also improves the injection of holes from the anode. By inserting another parylene layer in between the organic and cathode layers, the probability of formation of nonemissive areas is further reduced. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1498150
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  • 10
    Electronic Resource
    Electronic Resource
    Bubble formation due to electrical stress in organic light emitting devices (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 171-173 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The degradation in electroluminescence of poly(p-phenylene vinylene)-based organic light-emitting devices is studied using optical microscopy, scanning electron microscopy, and secondary ion mass spectroscopy. "Bubbles" are formed at the polymer and indium tin oxide interface or in the polymer layer within the nonemissive area. This formation, which occurs during device electrical stress, is accompanied by a fluctuation of the device current. The bubbles are formed by the degraded polymer and/or the gas released from disintegration of the polymer. High local current density flowing near the dark spot center and the resultant heating, decomposes the polymer layer. The resultant carbonized area causes either local short circuit and/or open circuit leading to the final light-emitting device failure. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1435064
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