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  • 1
    Electronic Resource
    Electronic Resource
    Optical intervalence-subband transitions in strained p-type In1−xGaxAs/InP quantum wells (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 5256-5262 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The lattice mismatch (strain) effects on the infrared absorption in p-type In1−xGaxAs/InP quantum wells are investigated systematically for both tensile (x(approximately-greater-than)0.47) and compressive (x〈0.47) strains. The mismatch of the valence-band parameters in the well and barrier materials is taken into account in the optical matrix element calculations. We find that normal incidence optical matrix elements substantially increase in the case of the compressive strain (the ground state is heavy hole) and decreases in the case of the tensile strain (the ground state is light hole). The peak of the normal incidence absorption in the compressively strained QW is shown to reach a considerable value of 5000–6000 cm−1 for a sheet hole concentration of 1012 cm−2. For the z-polarization of the light we found a substantial enhancement of the optical matrix elements in the case of tensile strain (i.e., for a light-hole ground state). © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359277
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  • 2
    Electronic Resource
    Electronic Resource
    Nitrogen acceptors confined in CdZnTe quantum well structures (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 2070-2073 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nitrogen acceptors confined in a CdZnTe single quantum well, grown by molecular beam epitaxy, are investigated by different optical methods. The transitions related to nitrogen acceptors confined in the well are observed in the doping range between 1017 and 1018/cm3. The temperature and excitation intensity dependence of the nitrogen-related transitions in photoluminescence spectra indicates that these transitions correspond to the nitrogen acceptor bound excitons and to free electron to neutral nitrogen acceptor recombination. The binding energy of nitrogen acceptors confined in an 130-A(ring)-wide Cd0.96Zn0.04Te/Cd0.86Zn0.12Te structure is deduced to be 51.7±0.5 meV from this study. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361063
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  • 3
    Electronic Resource
    Electronic Resource
    Hydrogen passivation of nitrogen acceptors confined in CdZnTe quantum well structures (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 2329-2332 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The deactivation of nitrogen acceptors confined in Cd0.96Zn0.04Te/Cd0.86Zn0.14Te quantum well structures by hydrogen (deuterium) have been investigated by optical spectroscopy. Hydrogen (deuterium) was incorporated into the samples by annealing them in an atmosphere of hydrogen and cadmium. The annealing temperature and annealing time were varied to determine the optimum condition at which the maximum passivation is achieved without causing structural degradation. The emissions related to nitrogen acceptors were monitored in low-temperature photoluminescence measurements in order to deduce the passivation effect. The results indicate that hydrogen can effectively neutralize the nitrogen acceptors in cadmium zinc telluride quantum well structures. It is estimated that as much as 90% of the nitrogen acceptors can be passivated by this method. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1388569
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of small amounts of Al in GaN grown on sapphire (0001) by molecular beam epitaxy (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 1954-1958 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A series of 0.7 μm thick GaN layers have been grown by solid-source rf-plasma assisted molecular beam epitaxy on sapphire (0001) substrates with the addition of 0.10%–3.30% Al. The Al concentration was determined by secondary ion-mass spectrometry and Auger-electron spectroscopy, while the layer quality was assessed by photoluminescence, Hall effect measurement, and high-resolution scanning electron microscopy. Microscopy revealed a surface roughness varying with Al content. The smallest surface roughness was obtained at 0.10% and 3.30% Al. Low-temperature photoluminescence revealed dominating peaks attributed to the neutral donor-bound exciton. Its energy increased slightly with Al concentration, which established a correlation between the Al concentration and the band gap. The surface morphology, the corresponding optical and electrical properties, showed a clear improvement of the GaN layer quality for the range of 0.10%–0.17% Al content. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1335647
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  • 5
    Electronic Resource
    Electronic Resource
    Theoretical investigation of shallow acceptors confined in Si/Si1−xGex quantum well structures (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 5624-5629 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Energy levels of the shallow acceptor states have been calculated for center-doped Si/Si1−xGex/Si quantum wells. The impurity states were calculated using an effective-mass theory that accounts for valence-band mixing as well as the mismatch of band parameters and dielectric constants between well and barrier materials. Acceptor binding energies and splitting between the acceptor 1S3/2(Γ7) and 1S3/2(Γ6) ground states were studied at various Ge concentrations and well widths. The results are discussed in comparison with the recent conclusion from the lateral transport measurements in boron-doped Si/SiGe quantum wells. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371571
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  • 6
    Electronic Resource
    Electronic Resource
    Optical properties of arsenic ions implanted GaAs/AlGaAs V-grooved quantum wires (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 2519-2522 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Asymmetric double GaAs/AlGaAs V-grooved quantum wires, grown by low pressure metalorganic chemical vapor deposition, are studied using photoluminescence (PL) spectroscopy. The structure was selectively treated by ion implantation at different arsenic (As) doses after growth. The ion implantation strongly reduces the efficiency of the emissions from the implanted well regions or even quenches the PL emissions from certain well regions due to irradiation damage. Wire emission is clearly resolved in the samples after treatment by low dose implantation. The temperature dependence of the wire emission intensity shows an enhancement at a temperature of around 45 K. The wire emission peak with a shoulder at its high energy side at low temperatures develops into double peaks in a temperature region between 20 and 140 K, and the high energy transition component dominates the PL spectra at temperatures above 140 K. The deduced energy separation between two peaks is about 10 meV. With further increasing temperatures the wire emission related to the light hole state can be observed at temperatures above 150 K. Deduced splitting between the heavy and light states is about 35 meV in our structures. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1287119
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of the first GaN monolayer on the nitridation damage of molecular beam epitaxy grown GaN on GaAs(001) (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 3662-3667 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The initial molecular beam epitaxy growth of GaN on GaAs(001) was studied by real-time monitoring of the (3×3) surface reconstruction and its transition to an unreconstructed (1×1). Various growth conditions were established by variation of the V/III ratio, i.e., the Ga flux. We characterized the effect of the first two strained GaN monolayers: a N-terminated GaN (3×3) monolayer and a second unreconstructed (1×1) monolayer. A series of samples were grown under N-rich, Ga-rich, and near-stoichiometric growth conditions. The resulting morphology of the interface region was analyzed by high-resolution scanning electron microscopy, Auger-electron spectroscopy, and double crystal x-ray diffractometry. The N-rich and Ga-rich conditions resulted in extensive defect formation due to the nitridation damage of the GaAs substrate. The extent of this was found to be determined by the properties of the first GaN monolayer. The surface roughness under optimum growth conditions could be as low as ∼20 nm, defined by nanocrystalline grains, showing no observable nitridation damage. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1345516
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  • 8
    Electronic Resource
    Electronic Resource
    Stress dependence of infrared absorption frequencies and oscillator strengths of acceptors confined in GaAs/AlGaAs quantum wells (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 3922-3924 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Infrared absorption of acceptors confined in a GaAs/AlGaAs quantum well (QW) has been calculated in the presence of an external stress. The absorption frequency and oscillator strength of the dominating infrared transitions of acceptors confined in the QW are examined. The effects of the confined QW potential and the applied stress on the acceptor binding energies are investigated. A simple relation between the acceptor ground state splitting and the first heavy hole-light hole subband splitting is obtained for a GaAs/AlGaAs QW. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369766
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  • 9
    Electronic Resource
    Electronic Resource
    Electron and hole g-factors in CdTe/CdMgTe quantum wells (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3704-3706 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single CdTe/CdMgTe quantum well (QW) structures are investigated by stationary and time-resolved photoluminescence in the presence of an applied magnetic field. We study the dependence of the electron and the hole g factors on the well width by combining Zeeman measurements and the recently developed spin quantum beats technique. The experimental results show that both the electron and the hole g factors have the same sign in wide QWs and increase with decreasing well width. The electron spin phase relaxation time is about 250 ps in our QW structures. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117195
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  • 10
    Electronic Resource
    Electronic Resource
    Photoluminescence of pseudomorphic SiGe formed by 74Ge+ ion implantation in the overlayer of silicon-on-insulator material (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 3047-3049 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A metastable SiGe-on-insulator structure is realized by a high-dose 74Ge+ ion implantation in the overlayer of silicon-on-insulator followed by solid phase epitaxial regrowth. Studies of the optical properties of the germanium-implanted and post-implantation annealed layers with 18% peak germanium concentration were carried out using photoluminescence (PL) spectroscopy. The electrical integrity of the strained layer was qualitatively inferred from the pseudo-mosfet characterization technique. The PL results show that the broadband (BB) emission related to germanium implantation damage can be completely eliminated by post-implantation thermal treatment. PL spectra and measured transconductance of the sample heat-treated at 500 °C indicate conclusively that a defect-free strained SiGe layer has been formed. However, samples heat-treated at higher temperatures show degradation in the charge carrier lifetime, a new BB emission with 0.816 eV peak energy and an emergence of defect related emission at 0.870 eV for samples annealed at and above 900 °C. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121536
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