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  • 1990-1994  (24)
  • 1945-1949  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Correlation of time-resolved electroluminescence and cathodoluminescence measurements on quantum well light emitters with varying barrier widths (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 5561-5569 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present results of a comparative study of the time-dependent luminescence properties of multiple quantum well structures with varying barrier widths which are embedded in the active area of a light-emitting device. The carrier kinetics is investigated by different experimental approaches: Cathodoluminescence and electroluminescence experiments where excitation is on/off-modulated for the purpose of time-resolved measurements and time-resolved electroluminescence experiments in the small signal regime which allow for observation of the carrier kinetics under flatband conditions. Due to the exact determination of the excess carrier density the latter technique provides a sensitive tool for a precise estimation of the mono- and bimolecular recombination coefficients. Comparison with light output data yields radiative and nonradiative parts. We find that coupling of quantum wells dramatically favors nonradiative interface recombination as expected from a theoretical model accounting for the superlattice wavefunctions. On the other hand, the bimolecular recombination rate remains unaltered even when the barrier width is lowered from 18 to 0.9 nm. In contrast, on/off modulated experiments reveal that luminescence decay is strongly influenced by carrier drift out of the active area. A barrier width dependent carrier mobility in growth direction accounts for these results if phonon assisted hopping rather than Bloch transport is presumed. Thus, an estimation of device quality of quantum well light emitters by conventional time-resolved cathodo- (or photo-) luminescence experiments is found to be possible if internal field induced carrier drift processes are taken into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350193
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    High-power single-mode AlGaAs lasers with bent-waveguide nonabsorbing etched mirrors (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2131-2135 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A nonabsorbing etched mirror structure for AlGaAs single-quantum-well graded-refractive-index separate-confinement heterostructure ridge lasers is analyzed with respect to mirror coupling coefficient, threshold current penalty, and far-field pattern. Measurements of the mirror temperature showed a reduction from 50 to 20 K at 30 mW optical power depending on the degree of overlap of the optical intensity with the absorbing bent-waveguide profile. Pulsed catastrophic optical damage power levels up to 400 mW and a thermally saturated cw power of 165 mW with single-mode operation up to 80 mW have been achieved. Lifetime measurements at 40 mW constant optical power indicated degradation rates ≤10−5/h comparable to AlGaAs lasers with cleaved and coated mirrors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351601
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Time-resolved investigations of sidewall recombination in dry-etched GaAs wires (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 2016-2018 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the sidewall recombination in dry-etched GaAs/GaAlAs wires with widths between 12 μm and 300 nm using picosecond spectroscopy. The wires were fabricated with electron beam lithography and different reactive ion etching processes. The excitonic lifetimes decrease strongly with decreasing wire widths due to sidewall recombination. Using a model calculation to fit the experimentally observed width dependence of the lifetimes the surface recombination velocity is determined to be S=2×106 cm/s at 50 K. S increases with temperature and is independent of the etching process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103003
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    High-power single-mode strained single quantum well InGaAs/AlGaAs lasers grown by molecular beam epitaxy on nonplanar substrates (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1939-1941 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strained single quantum well InGaAs/AlGaAs graded-index separate confinement heterostructure lasers have been grown by molecular beam epitaxy over nonplanar substrates. In addition to the low threshold currents provided in situ by lateral current blocking pn junctions obtained by plane-dependent doping of the amphoteric Si dopant, we observe variations in lasing wavelength, efficiency, and internal absorption as a function of the central (100) facet length. These variations are associated with increased indium composition in the strained quantum well which arises from incorporation of adatoms migrating from the low-growth (311)A side facets to the preferential growth (100) active area facets. Uncoated devices (750 μm×4 μm) have been found to have threshold currents as low as 6 mA (Jth=320 A/cm2) and exhibit single-mode behavior to greater than 100 mW at a wavelength of ∼1.0 μm when reflectivity modified (90%/10%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103028
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Nanometer resolution in luminescence microscopy of III-V heterostructures (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1564-1566 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In a scanning tunneling microscope experiment, the luminescence induced by the recombination of holes with electrons tunneling into cleaved (110) GaAs/AlGaAs heterostructures is used to image the interface region with nanometer resolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103154
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Tunneling microscopy and spectroscopy of molecular beam epitaxy grown GaAs-AlGaAs interfaces (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 31-33 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the first observation of GaAs/AlGaAs compound multilayers and interfaces at atomic scale resolution. Using a scanning tunneling microscope, the atomic registry in the epitaxial layers and their interfaces was observed. The semiconductor band gaps and valence-band offsets relative to the Fermi level are obtained via local spectroscopy in the GaAs and AlGaAs multilayers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103563
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Atomic-scale view of AlGaAs/GaAs heterostructures with cross-sectional scanning tunneling microscopy (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 1273-1275 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Atomically resolved cross-sectional scanning tunneling microscope topographic images of heterostructures that include a sequence of 1, 2, 5, and 10 nm AlGaAs and GaAs layers are presented. These layers clearly show alloy fluctuations and interface roughness on an atomic scale. In the thick AlGaAs layers a mottled structure with regions of higher Al content about 2 nm wide and elongated in [1¯12] or [11¯2] directions are observed. Similarly, the interfaces are rough on a 2 nm length scale. These results suggest that, for the conditions used for the epitaxial growth of the ternary layers, Al-rich regions nucleate and grow anisotropically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109755
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Dopant and carrier profiling in modulation-doped GaAs multilayers with cross-sectional scanning tunneling microscopy (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 3636-3638 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the direct measurement of dopant and carrier density profiles in GaAs (001) modulation-doped structures using cross-sectional scanning tunneling microscopy. On ultrahigh-vacuum-cleaved cross-sectional (110) GaAs surfaces, individual electrically active dopants are observed as hillocks in the top several surface layers, and the tip-sample separation is found to be sensitive to the carrier concentration. In structures where the conventionally measured p-type dopant concentration varied from 1×1018 to 1×1019 cm−3 the density of such dopant hillocks varies accordingly and the tip-sample separation changes by 0.1 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110073
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Optical suppression of ionized impurity scattering in vertical hot-electron transport (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 3157-3159 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A striking effect of illumination on the vertical nonequilibrium electron transport has been observed in the GaAs-based tunneling hot electron transfer amplifier (THETA). Weak illumination can considerably increase the transparency of a THETA structure for quasiballistic electrons if the photon energy exceeds the GaAs band gap. The temperature and illumination intensity dependencies indicate that the effect is caused by photoneutralization of ionized impurities which are a major source of hot electron scattering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107962
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Gallium desorption during growth of (Al,Ga)As by molecular beam epitaxy (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1222-1224 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new two-phase model for gallium desorption can quantitatively explain the change of the desorption energy as a function of the III/V ratio. In this model, the gallium loss rate is described as a phenomenon of simultaneous desorption from a Ga fluid state and a GaAs solid state. This behavior was experimentally verified by accurate thickness measurements of epitaxial AlxGa1−xAs layers by transmission electron microscopy. The results show the Ga loss rate is directly dependent only on the Ga coverage on the surface, while the desorption energy is independent of the aluminum concentration. By varying the III/V ratio, we found that the Ga desorption energy increases from 3.1 eV at low arsenic flux to 4.7 eV at high arsenic flux.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107601
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