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  • 1
    Electronic Resource
    Electronic Resource
    A self-consistent approach to spectral hole burning in quantum wire lasers (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6451-6453 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In a semiconductor laser above threshold, carriers are extracted at the lasing energy at a high rate due to stimulated emission and are injected at higher energies. This creates a "hole burning'' phenomenon resulting in gain compression. This effect is studied in a quantum wire laser by solving the Boltzmann equation with sink and source terms by a novel Monte Carlo technique. The results for various values of the characteristic injection times are given. A formalism is also proposed for the fully self-consistent determination of the laser operating parameters from the rate equations with the inclusion of nonlinear gain effects by substituting the correct form of the distribution function in presence of hole burning into the standard expressions for the laser material gain. The nonlinear gain effect is then described completely starting from the wire band structure and scattering rates. The generality of the proposed technique and its possible extensions and applications to the problem of nonlinear gain in quantum-well lasers are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355131
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  • 2
    Electronic Resource
    Electronic Resource
    Optimum separate confinement structure for midinfrared HgCdTe heterostructure lasers (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2043-2048 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A study for the optimization of HgCdTe heterostructure lasers for applications as midinfrared wavelength sources has been carried out. Structures are examined to emit photons at 2.5 and 4.5 μm at 77 K. For the 2.5 μm case, it is found that a quantum-well laser with well width of 200 A(ring) in a separate confinement structure is optimum. For the 4.5 μm case the optimum structure is one with a 1000 A(ring) active region. For the 4.5 μm case the high carrier density at threshold in quantum wells and the consequent high Auger rates do not allow the decrease of threshold current with smaller well sizes. This result is rather general for narrow-gap zinc-blende semiconductors and represents a cautionary warning against the commonly held belief that narrow quantum wells will always improve threshold currents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351632
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  • 3
    Electronic Resource
    Electronic Resource
    Electric-field dependence of acceptor-level binding energies in strained SiGe and InGaAs quantum-well structures (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 2023-2024 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The acceptor energies for strained SiGe (on Si) and InGaAs (on GaAs) quantum wells are calculated from a 4×4 k⋅p band structure that includes the effects of strain and electric fields. Both center- and edge-doped cases are examined. The theory shows marked changes in the acceptor energies with both strain and electric field. The wide variation in binding energy for the edge-doped quantum wells may provide a mechanism for tunable far-infrared detectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351143
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  • 4
    Electronic Resource
    Electronic Resource
    A model for high-field transport in alloys: Application to In0.53Ga0.47As (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 322-324 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose a new model for alloy scattering in semiconductor alloys in which the alloy scattering potential is allowed to have an energy dependence which is calculated from the band structures of the components. At low electric fields this model reduces to the conventional model based on electronegativity differences of the components. At high fields where the electron distribution function is shifted to higher electron energies, our model leads to reduced alloy scattering. This in turn leads to a reduction in the threshold fields and an increase in peak velocities. This model is applied to In0.53Ga0.47As and the results thus obtained are compared with the available experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.334807
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  • 5
    Electronic Resource
    Electronic Resource
    Role of interface roughness and alloy disorder in photoluminescence in quantum-well structures (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 5433-5437 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A formalism to study the effect of alloy disorder and interface roughness on the linewidths of excitonic emission spectra in quantum-well structures is developed. The study includes the cases where the alloy forms (a) the barrier region, (b) the well region, and (c) both the barrier and well regions of the quantum-well structures, and demonstrates the importance of alloy quality in all three cases. The relative importance of the effects of alloy disorder and interface roughness on the excitonic linewidths is discussed. As an illustration, the formalism is applied to AlGaAs/GaAs, InP/InGaAs, and InAlAs/InGaAs quantum-well structures and the results compared with the available experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.334818
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  • 6
    Electronic Resource
    Electronic Resource
    Current–voltage characteristics of polar heterostructure junctions (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 2989-2993 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report calculations that show that a metal–polar semiconductor heterostructure can exhibit highly controllable nonlinear current–voltage characteristics. A change in barrier thickness can alter the characteristics from Schottky-like to ohmic in different bias regimes. The origin of these unusual effects is a large electric field (〉106 V/cm) and high sheet charge(∼1013–1014cm−2) without doping, in the polar heterostructure. Theoretical calculation of the tunneling current density in these systems is done in this work. The results indicate that very interesting nonlinear behavior is shown by these systems, even in the undoped case. The choice of suitable compositions of the materials and thicknesses can be used to tailor devices with desired characteristics. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1434542
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  • 7
    Electronic Resource
    Electronic Resource
    Initial stages of GaN/GaAs(100) growth by metalorganic chemical vapor deposition (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 1823-1829 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A study of GaN buffers grown by metalorganic chemical vapor deposition on (001) GaAs substrates was performed. Nucleation images obtained by atomic force microscopy (AFM) were employed to investigate the growth temperature, growth time, and growth rate dependence of the nucleation mechanisms. The growth mode corresponds to two-dimensional (2D) island nucleation at low temperatures, while three-dimensional (3D) island growth is observed at high temperatures. Large grain sizes and good surface coverage was obtained for 3 min growth. Higher growth rates help nucleation on mismatched substrate and promote the 2D growth mode. GaN films 0.5 μm thick were grown on different buffers using a two-step technique as suggested by the AFM analysis and their morphology was found to improve when grown on optimized buffers. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362994
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  • 8
    Electronic Resource
    Electronic Resource
    Dynamic instabilities in the power spectrum of deeply modulated semiconductor lasers (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4003-4006 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Semiconductor lasers under large-signal direct modulation by a square waveform are found to exhibit a transition from a power spectrum characterized by a fundamental frequency and FM sidebands to a continuous spectrum with a catastrophically broadened linewidth of the order of several GHz. The interesting feature of the phenomenon is that the photon output remains periodic apart from noise-induced fluctuations, and the broadening of the power spectrum is attributed to the sensitivity of the phase of the optical field to a large difference in the relaxation oscillation frequencies in the on and off states as well as the coupling between motions at the intrinsic resonance frequency of the system and the externally-imposed modulation frequency. It is shown that under deep modulation by a periodic injection current, the optical phase becomes aperiodic generating a wide range of new frequencies in the power spectrum. It is also demonstrated that by confining the excursions of the injection current to the region of almost-linear optical response, linewidth broadening may be avoided. Quantitative criteria for determining the boundary of the broadened-linewidth region are presented for several modulation frequencies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357346
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  • 9
    Electronic Resource
    Electronic Resource
    Theoretical study of GaN growth: A Monte Carlo approach (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 3502-3510 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An atomistic model consistent with a variety of experimental observations is developed for GaN growth by molecular-beam epitaxy. The model is used in Monte Carlo simulation to study the impact of substrate temperature, Ga flux, and V/III (group-V element to group-III element) ratio on growth rate and growth front quality. The growth rate increases with the V/III ratio reaching a saturation value which is determined by the Ga flux. The quality of the growth front improves by using a smaller Ga flux for a fixed temperature and V/III ratio or by reducing the V/III ratio at a given temperature. A consideration of the growth kinetics suggests that GaN grown surfaces are likely to be Ga stabilized. These theoretically estimated trends are evidenced by two-dimensional and three-dimensional growth front contours evaluated under various growth conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357479
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  • 10
    Electronic Resource
    Electronic Resource
    Polarization dependence of the absorption coefficient for an array of strained quantum wires (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 4931-4934 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The polarization dependence of the absorption coefficient for compressively and tensilely strained quantum wires is investigated as a function of strain, the lateral wire width, and the ratio between the wire and barrier widths. The results are markedly different from the case of an unstrained quantum wire and exhibit a significant variation with the sign and amount of built-in strain. In the case of compressive strain, absorption of light polarized in the growth direction is considerably suppressed near the band edge, while the ratio between the absorption coefficients for light polarized parallel and perpendicular to the wire is determined by the relative prominence of strain and quantum confinement effects. A discussion of how these results can be applied to characterization of the achieved quantum confinement by polarization-resolved photoluminescence spectroscopy is given. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359553
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