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  • 1
    Electronic Resource
    Electronic Resource
    Orientation dependence of valence-subband structures in GaAs-Ga1−xAlxAs quantum-well structures (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 4609-4613 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Valence-subband structures of GaAs-Ga1−xAlxAs quantum wells growth in the [001], [111], and [110] directions are calculated based on the bond-orbital model. The effective mass for the first subband in (111)-oriented quantum wells is found to be substantially smaller than that in (001)-oriented quantum wells for well widths narrower than 70 A(ring). The subband structures of (110)-oriented quantum wells display large anisotropy, with effective masses along two different in-plane directions ([001] and [11¯0]) differing by almost one order of magnitude. It is also found that the Al composition has a strong effect on the hole effective mass. Implications of our results in device applications are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342466
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  • 2
    Electronic Resource
    Electronic Resource
    Systematic study of Ga1−xInxAs self-assembled quantum wires with varying interfacial strain relaxation (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 2251-2260 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A systematic theoretical study of the electronic and optical properties of Ga1−xInxAs self-assembled quantum wires (QWRs) made of short-period superlattices with strain-induced lateral ordering is presented. The theory is based on the effective bond-orbital model combined with a valence-force-field (VFF) model. Valence-band anisotropy, band mixing, and effects due to local strain distribution at the atomistic level are all taken into account. Several structure models with varying degrees of alloy mixing for lateral modulation are considered. A VFF model is used to find the equilibrium atomic positions in the QWR structure by minimizing the lattice energy. The strain tensor at each atomic (In or Ga) site is then obtained and included in the calculation of electronic states and optical properties. It is found that different local arrangement of atoms leads to very different strain distribution, which in turn alters the optical properties. In particular, we find that in model structures with thick capping layer the electrons and holes are confined in the Ga-rich region and the optical anisotropy can be reversed due to the variation of lateral alloy mixing, while for model structures with thin capping layer the electrons and holes are confined in the In-rich region, and the optical anisotropy is much less sensitive to the lateral alloy mixing. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1323540
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  • 3
    Electronic Resource
    Electronic Resource
    Optical properties of GaAs/AlxGa1−xAs multiple quantum wells versus electric field including exciton transition broadening effects in optical modulators (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 2618-2627 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A systematic study of the refractive index and absorption coefficient of GaAs/AlxGa1−xAs quantum wells as a function of electric field is presented. In this model, the effective-mass mismatches between GaAs and AlxGa1−xAs have been considered. For the interband optical absorption, we have considered the effect of the final-state interactions, and found an analytical function well describing this effect. The line-shape functions and their appropriate linewidths due to the inhomogeneous broadening mechanisms have been considered as a function of layer thicknesses, Al fraction, electric field, and residual doping density in the intrinsic multiple-quantum-well (MQW) region of a p-i-n optical modulator. The calculated absorption coefficient as a function of wavelength and electric field agrees very well with the experimental data. The calculated refractive index is indirectly verified by comparing the calculated reflectance spectra with the measured data of a MQW reflection modulator.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356237
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  • 4
    Electronic Resource
    Electronic Resource
    Theory of electron resonant tunneling of Si-based double-barrier structures (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2402-2410 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present theoretical studies of resonant-tunneling characteristics of Si-based double-barrier structures within a tight-binding model. The model consists of four antibonding (sp3) orbitals per lattice site and is capable of describing the low-lying conduction bands accurately throughout the entire Brillouin zone. Current-voltage curves for some selected Si/Ge strained-layer double-barrier structures and lattice-matched Si/GaP double-barrier structures for different crystallographic orientations are calculated. Negative differential resistances are found for these structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353094
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  • 5
    Electronic Resource
    Electronic Resource
    Linear and two-photon absorptions of Si-Ge strained-layer superlattices (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1349-1360 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Linear and two-photon absorption spectra of Si-Si0.5Ge0.5 strained-layer superlattices grown along [001], [111], [110] directions are calculated within a realistic microscopic model. The temperature dependence of carrier lifetimes due to deformation-potential scattering (including intra- and intervalley scattering) has been taken into account. It is found that superlattices grown along the [110] direction are most promising for applications both in far-infrared detection and in optical limiting. The value for the two-photon absorption coefficient at 77 K for an incident 10.6-μm radiation polarized parallel to the layer can be as high as 150–2000 cm/MW with a linear absorption coefficient around 600–3500 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351253
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  • 6
    Electronic Resource
    Electronic Resource
    Optical properties of Hg1−xCdxTe sawtooth superlattices (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 829-834 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Theoretical studies of the band structures, photoabsorption, electro-optic coefficient, and second-order susceptibility (χ(2)) of Hg1−xCdxTe sawtooth superlattices are reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343504
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  • 7
    Electronic Resource
    Electronic Resource
    Linear and two-photon absorption of rectangular and sawtooth HgTe/CdTe superlattices (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 4233-4241 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Theoretical studies of linear and two-photon absorption spectra of HgTe/CdTe superlattices with rectangular and sawtooth potential profiles are reported. Under optimum condition, the two-photon absorption coefficient can be higher than 1 cm/kW. The possible application of these materials as optical limiters near 10 μm wavelength is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346214
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  • 8
    Electronic Resource
    Electronic Resource
    Electronic structures of In1−xGaxAs-InP strained-layer quantum wells (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 3096-3100 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The band structures of In1−xGaxAs-InP strained-layer quantum wells are investigated theoretically in the bond-orbital model. For small x, the well material is subject to a compressive biaxial strain which lifts the HH1 subband further apart from the LH1 subband, resulting in smaller in-plane effective mass for holes. For large x, the strain becomes tensile and the LH1 subband is lifted upward with respect to the HHl subband. For x near the critical value, where the HHl and LHl energy levels cross each other, the valence-band structure undergoes a direct-to-indirect transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342705
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  • 9
    Electronic Resource
    Electronic Resource
    The effects of crystallography and lateral intermixing on the subband structure and optical anisotropy in quantum-wire arrays on vicinal substrates in the layer-orbital model (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 867-875 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Materials-characterization studies indicate a high degree of lateral intermixing in quantum-wire arrays grown on vicinal substrates. In this study, the layer-orbital model, which is a variation of the effective bond-orbital model, is used to calculate the zone-center conduction- and valence-subband energies and optical matrix elements of recently grown epitaxially buried GaAs/AlGaAs/AlAs quantum wires and quantum-wire arrays. The lateral intermixing effect is included using a compositional profile that has the merit that it is appropriate for the entire range of lateral intermixing, whether small or large, and that is computationally efficient. The effect of the orientation of the quantum wires on the subbands and the optical matrix elements is also investigated. For uncoupled quantum wires, the orientation mainly affects the positions of the valence subbands; the optical matrix elements are nearly independent of the orientation. The situation for the quantum-wire array is more complicated due to its intermediate nature between one and two dimensional. It is found that only the position of the light-hole subband is appreciably affected. It is also found that quantum-wire arrays misoriented from the [011] ([01¯1]) direction display somewhat reduced optical anisotropy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349650
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  • 10
    Electronic Resource
    Electronic Resource
    Theory of optical anisotropy in quantum-wire arrays on vicinal substrates (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 2685-2687 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effective bond-orbital model is used to calculate the conduction- and valence-subband structures and optical matrix elements of recently grown epitaxially buried GaAs/AlGaAs/AlAs quantum-wire arrays. Band mixing, band anisotropy, and lateral intermixing of Ga and Al during growth strongly affect the energy levels and features in the optical data. Strong anisotropy in the optical properties is predicted for the case of perfect lateral interfaces while for cases with significant lateral intermixing, the optical properties show weak anisotropy. Our results are compared with the observed photoluminescence excitation spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348666
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