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  • 1
    Electronic Resource
    Electronic Resource
    Excess carrier lifetime and ambipolar diffusion anisotropy in a nipi-doped In0.2Ga0.8As/GaAs multiple-quantum-well structure (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7014-7020 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of strain-induced structural defects in a nipi-doped In0.2Ga0.8As/GaAs multiple-quantum well sample were studied with time-resolved electron-beam-induced absorption modulation, in which carrier recombination lifetimes and ambipolar diffusion constants are measured with high spatial, spectral, and temporal resolution. Based on a phenomenological model, carrier lifetimes in the limit of weak excitation at room temperature were determined. The lifetime is found to be reduced by a factor of ∼1013 compared to a theoretically calculated value, owing to the presence of strain-induced defects and alternate recombination channels. By using a two-dimensional diffusion model, the ambipolar diffusion coefficients Da along high-symmetry [110], [11¯0], and [100] directions were determined and resulted in an anisotropic behavior such that D[110]a(approximately-greater-than)D[11¯0]a (approximately-greater-than)D[100]a. The anisotropy in diffusion is attributed to corresponding asymmetries in the misfit dislocation density. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361467
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of structural defects on carrier recombination and current gain in an InGaAs/AlGaAs/GaAs heterojunction phototransistor (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8015-8023 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the influence of structural defects on the spatial variation of radiative and nonradiative recombination in an InGaAs/AlGaAs/GaAs resonant cavity enhanced npn heterojunction phototransistor (HPT) structure using cathodoluminescence (CL) and electron beam-induced current (EBIC) imaging. Absorber layers of InGaAs/GaAs multiple quantum wells (MQWs) are used to provide the photosensitivity for light with wavelengths that are transparent to the GaAs substrate. The current gain of the HPT under an applied bias voltage depends on the hole accumulation efficiency in the base and therefore on the hole lifetime. Strain relaxation-induced misfit dislocations in the MQWs are found to create regions of enhanced nonradiative recombination thereby reducing locally the hole accumulation efficiency and current gain. The reduction in the local EBIC signal caused by the dark line defects is less than ∼20%, suggesting that misfit dislocations in this sample have a relatively small impact on overall device performance. EBIC and CL are found to be excellent complementary probes of the hole accumulation efficiency and relative recombination rates, owing to the high spatial resolution (∼1 μm) of excitation of the electron beam used in these techniques. The temperature dependence of the EBIC and spectrally integrated CL images is examined for 85≤T≤300 K, and reveals that nonradiative recombination in the vicinity of misfit dislocations is predominantly thermally activated with observed spatial variations in lifetime and activation energy. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362353
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of misfit dislocations on thermal quenching of luminescence in InxGa1−xAs/GaAs multiple quantum wells (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 6687-6690 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The temperature dependence of the cathodoluminescence (CL) originating from In0.21Ga0.79As/GaAs multiple quantum wells has been studied between 86 and 250 K. The CL intensity exhibits an Arrenhius-type dependence on temperature (T), characterized by two different activation energies. The influence of misfit dislocations and point defects associated with strain relaxation on the thermal quenching of luminescence has been investigated, and the spatial variation in the activation energies has been examined. The CL intensity dependence on temperature for T(approximately-less-than)150 K is controlled by thermally activated nonradiative recombination. For T(approximately-greater-than)150 K the decrease in CL intensity is largely influenced by thermal re-emission of carriers out of the quantum wells. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360491
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of defects on electron–hole plasma recombination and transport in a nipi-doped InxGa1−xAs/GaAs multiple-quantum well structure (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 6557-6568 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The nonlinear optical and transport properties of a nipi-doped InxGa1−xAs/GaAs multiple-quantum well sample (x=0.23) has been studied using a novel approach called electron-beam-induced absorption modulation (EBIA). The absorption in the sample is modulated as a result of screening of the built-in electric field in the nipi structure due to excess carrier generation. The change in field causes a Stark shift of the first quantized optical transitions in QWs which are situated in the intrinsic layers. In EBIA, a scanning electron probe is used to locally generate an electron–hole plasma that is used to study the spatial distribution of defects that impede excess carrier transport and reduce the lifetime of spatially separated carriers. The Stark shift in the MQW structure is imaged with micrometer-scale resolution and is compared with cathodoluminescence imaging results which show dark line defects resulting from strain-induced misfit dislocations. Theoretical calculations using Airy functions in the transfer-matrix method with a self-consistent field approximation were used to determine the energy states, wave functions, and carrier recombination lifetimes of the MQW as a function of the built-in field. A quantitative phenomenological analysis is employed to determine the built-in field, excess carrier lifetime, and ambipolar diffusion coefficient as a function of the excitation density. The defects are found to create potential barriers and recombination centers which impede transport and markedly reduce the excess carrier lifetime. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359065
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  • 5
    Electronic Resource
    Electronic Resource
    Lateral coherence properties of broad-area semiconductor quantum well lasers (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 66-68 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The lateral coherence of broad-area lasers fabricated from a GaAs/GaAlAs graded index waveguide separate confinement and single quantum well heterostructure grown by molecular-beam epitaxy was investigated. These lasers exhibit a high degree of coherence along the junction plane, thus producing a stable and very narrow far field intensity distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337629
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  • 6
    Electronic Resource
    Electronic Resource
    Cathodoluminescence and transmission electron microscopy study of dark line defects in thick In0.2Ga0.8As/GaAs multiple quantum wells (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5834-5839 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The spatial distribution of the long-wavelength luminescence in thick In0.2Ga0.8As/GaAs multiple quantum wells (MQWs) has been investigated using cathodoluminescence (CL) imaging and spectroscopy. The CL spectra show defect-induced broad bands between 1000(approximately-less-than)λ(approximately-less-than)1600 nm. These bands exhibit spatial variations which correlate with the dark line defects (DLDs) observed in the λ=950 nm exciton luminescence imaging. Transmission electron microscopy showed that [110]-oriented misfit dislocations occur primarily at the substrate-to-MQW and GaAs capping layer-to-MQW interfaces. The large spatial variation of the luminescence intensities indicates that the DLDs observed in CL images are caused by the presence of nonradiative recombination centers occurring in the MQW region located between the interface misfit dislocations. This study provides new information describing the origin and nature of DLDs and differs from previous models which have regarded the electronic nature of dislocation cores as the primary mechanism for inducing DLD radiative contrast in luminescence imaging of strained InGaAs/GaAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351939
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  • 7
    Electronic Resource
    Electronic Resource
    Optically induced absorption modulation in a periodically δ-doped InGaAs/GaAs multiple quantum well structure (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1946-1948 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strong optically induced absorption modulation has been achieved in a periodically δ-doped InGaAs/GaAs multiple quantum well structure. The use of δ-doping has enabled efficient modulation in short-period structures using a low-power semiconductor laser. With an excitation intensity of 100 mW/cm2 we have measured an absolute quantum well absorption change of more than 9000 cm−1 corresponding to a differential absorption change as high as 58% at the excitonic resonance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105027
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  • 8
    Electronic Resource
    Electronic Resource
    Single-ended output GaAs/AlGaAs single quantum well laser with a dry-etched corner reflector (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1934-1936 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaAs/AlGaAs single quantum well lasers with integrated corner reflectors have been fabricated using chemically assisted ion beam etching. The air-GaAs interface is internally totally reflecting, and no coherent radiation is transmitted through the corner reflector. The corner reflector laser was compared with a conventional Fabry–Perot laser cleaved from the same wafer. An 11% reduction in threshold current and a reduction of the far-field angle from 4.4° to 0.7° was measured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103026
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  • 9
    Electronic Resource
    Electronic Resource
    Highly efficient pseudomorphic InGaAs/GaAs/AlGaAs single quantum well lasers for monolithic integration (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1731-1733 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Highly efficient ridge waveguide pseudomorphic single quantum well lasers, emitting at 980 nm, have been fabricated from an In0.2Ga0.8As/GaAs/AlGaAs graded-index separate confinement heterostructure grown by molecular beam epitaxy. The lateral index guiding provided by the ridge reduces the anomalously large lateral loss of optical power found in gain-guided structures, thereby reducing the internal loss by more than 50%. The low threshold current (7.6 mA) and high differential quantum efficiency (79%) obtained under continuous operation as well as the transparency of the GaAs substrate to the emitted radiation render these lasers attractive for GaAs-based optoelectronic integration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103106
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  • 10
    Electronic Resource
    Electronic Resource
    Photon-assisted resonant tunneling through variably spaced superlattice energy filters (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1297-1298 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the observation of photon-assisted resonant tunneling in a multiple quantum well structure composed of doped quantum wells separated by variably spaced superlattice energy filters. Electrons confined in the quantum wells are excited to the second quantized state by intersubband absorption of incident infrared radiation and are subsequently emitted through the filters under appropriate bias conditions. This is manifested by a distinct peak, with an associated negative differential photoconductance, in the photocurrent versus bias voltage characteristic at low temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104341
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