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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 4555-4559 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A novel luminescence technique named photothermal luminescence has been developed. For the photothermal luminescence spectroscopy, the emission signal is caused by electronic transitions via the absorption of photons, followed by thermal excitation via electron-phonon interactions, and is monitored as a function of the excitation photon energy, in which the excitation photon energy is less than that of the emission signal. This new technique has been applied to the study of electronic transitions in GaAs/AlxGa1−xAs quantum wells. In addition to the observation of the n=1 electron-heavy-hole 1s and 2s exciton recombinations, a previously unreported fine structure in the n=1 electron-heavy-hole 1s exciton spectrum has also been observed. By measuring the temperature dependence of the spectra on different quantum wells, we suggest that the fine structure is due to the formation of the standing waves of acoustic vibrations in GaAs/AlxGa1−xAs quantum wells. We emphasize that due to the underlying mechanism of the technique, the photothermal luminescence provides a powerful tool to investigate the processes of electron-phonon interactions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 647-650 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the optical properties of high density electron gas in GaAs/Al0.3Ga0.7As modulation doped quantum wells by using the photoluminescence measurements with the pumping photon energies above and below the band gap of the barrier and the resonant Raman scattering. We point out that the previous assignment of the transition between the second conduction subband and the ground-state heavy-hole subband in the photoluminescence spectra may be flawed. Thus, there is no large breakdown of the parity selection rule of the optical matrix element in quantum wells even if the carrier concentration is as high as 1012 cm−2. Our results are consistent with the theoretical investigation. We have also estimated the band gap shrinkages due to many-body interactions, which are comparable with the previous calculations.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1040-1042 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence measurement is used to study the properties of In0.53Ga0.47As epilayers grown on InP-coated GaAs substrates. Several structures are designed to test the qualities of the epilayers. It is shown that device-quality In0.53Ga0.47As on a GaAs substrate can be achieved. The effects of hydrogenation using a photochemical-vapor-deposition system are studied, and an enhancement of the band-edge luminescence intensity by a factor of 4 is observed. The resulting intensity even exceeds that of the film grown directly on a lattice-matched InP substrate. In addition, the emission coming from lattice defects is greatly reduced after hydrogenation. These results not only further support the potential application of using binary buffer layer concepts in large lattice-mismatched systems, but also demonstrate that the photochemical-vapor-deposition system is a useful tool for injecting hydrogen into InGaAs epilayers. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2543-2545 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report an investigation of optical and electronic properties in InAlAs/InGaAs heterojunction bipolar transistor layers by optical detection of cyclotron resonance (ODCR). Strong ODCR spectra structured by quantum oscillations have been observed, from which the effective mass and the carrier concentration of the two-dimensional electron gas can be obtained. The measured cyclotron mass is heavier than the conduction-band-edge mass in bulk InGaAs. We find that the carrier concentration increases with the spacer thickness. Quite unexpectedly, we also find that the effective mass increases with decreasing the carrier concentration. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 727-727 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
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