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  • 1
    Electronic Resource
    Electronic Resource
    Valence hole subbands and optical gain spectra of GaN/Ga1−xAlxN strained quantum wells (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 3471-3478 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The valence hole subbands, TE and TM mode optical gains, transparency carrier density, and radiative current density of the zinc-blende GaN/Ga0.85Al0.15N strained quantum well (100 A(ring) well width) have been investigated using a 6×6 Hamiltonian model including the heavy hole, light hole, and spin-orbit split-off bands. At the k=0 point, it is found that the light hole strongly couples with the spin-orbit split-off hole, resulting in the so+lh hybrid states. The heavy hole does not couple with the light hole and the spin-orbit split-off hole. Optical transitions between the valence subbands and the conduction subbands obey the Δn=0 selection rule. At the k≠0 points, there is strong band mixing among the heavy hole, light hole, and spin-orbit split-off hole. The optical transitions do not obey the Δn=0 selection rule. The compressive strain in the GaN well region increases the energy separation between the so1+lh1 energy level and the hh1 energy level. Consequently, the compressive strain enhances the TE mode optical gain, and strongly depresses the TM mode optical gain. Even when the carrier density is as large as 1019 cm−3, there is no positive TM mode optical gain. The TE mode optical gain spectrum has a peak at around 3.26 eV. The transparency carrier density is 6.5×1018 cm−3, which is larger than that of GaAs quantum well. The compressive strain overall reduces the transparency carrier density. The Jrad is 0.53 kA/cm2 for the zero optical gain. The results obtained in this work will be useful in designing quantum well GaN laser diodes and detectors. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363217
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  • 2
    Electronic Resource
    Electronic Resource
    Electronic properties of zinc-blende GaN, AlN, and their alloys Ga1−xAlxN (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 188-194 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electronic properties of wide-energy gap zinc-blende structure GaN, AlN, and their alloys Ga1−xAlxN are investigated using the empirical pseudopotential method. Electron and hole effective mass parameters, hydrostatic and shear deformation potential constants of the valence band at Γ and those of the conduction band at Γ and X are obtained for GaN and AlN, respectively. The energies of Γ, X, L conduction valleys of Ga1−xAlxN alloy versus Al fraction x are also calculated. The information will be useful for the design of lattice mismatched heterostructure optoelectronic devices based on these materials in the blue light range application. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360930
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  • 3
    Electronic Resource
    Electronic Resource
    A voltage-controlled tunable two-color infrared photodetector using GaAs/AlAs/GaAlAs and GaAs/GaAlAs stacked multiquantum wells (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2114-2116 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A voltage-controlled tunable two-color infrared detector with photovoltaic (PV) and photoconductive (PC) dual-mode operation at 3–5 μm and 8–14 μm using GaAs/AlAs/AlGaAs double barrier quantum wells (DBQWs) and bound-to-continuum GaAs/AlGaAs quantum wells is demonstrated. The photoresponse peak of the photovoltaic GaAs/AlAs/GaAlAs DBQWs is at 5.3 μm, and that of the photoconductive GaAs/GaAlAs quantum wells is at 9.0 μm. When the two-color detector is under a zero bias, the spectral response at 5.3 μm is close to saturate and the peak detectivity at 80 K can reach 1.0×1011 cmHz1/2/W, while the spectral photoresponsivity at 9.0 μm is absolutely zero completely. When the external voltage of the two-color detector is changed to 2.0 V, the spectral photoresponsivity at 5.3 μm becomes zero while the spectral photoresponsivity at 9.0 μm increases comparable to that at 5.3 μm under zero bias, and the peak detectivity (9.0 μm) at 80 K can reach 1.5×1010 cmHz1/2/W. Strictly speaking, this is a real bias-controlled tunable two-color infrared photodetector. We have proposed a model based on the PV and PC dual-mode operation of stacked two-color QWIPs and the effects of tunneling resonance with narrow energy width of photoexcited electrons in DBQWs, which can explain qualitatively the voltage-controlled tunable behavior of the photoresponse of the two-color infrared photodetector. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115602
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  • 4
    Electronic Resource
    Electronic Resource
    Quantum-confined magneto-Stark effect in diluted magnetic semiconductor coupled quantum wells (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1788-1790 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magneto-Stark effect in a diluted magnetic semiconductor (DMS) coupled quantum well (CQW) induced by an in-plane magnetic field is investigate theoretically. Unlike the usual electro-Stark effects, in a DMS CQW the Lorenz force leads to a spatially separated exciton. The in-plane magnetic field can shift the ground state of the magnetoexciton from a zero in-plane center of mass (CM)/momentum to a finite CM momentum, and render the ground state of magnetoexciton stable against radiative recombination due to momentum conservation. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1459491
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  • 5
    Electronic Resource
    Electronic Resource
    Empirical pseudopotential band-structure calculation for Zn1−xCdxSySe1−y quaternary alloy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3948-3955 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The band structure of the Zn1−xCdxSySe1−y quaternary alloy is calculated using the empirical pseudopotential method and the virtual crystal approximation. The alloy is found to be a direct-gap semiconductor for all x and y composition. Polynomial approximation is obtained for the energy gap as a function of the composition x and y. Electron and hole effective masses are also calculated along various symmetry axes for different compositions and the results agree fairly well with available experimental values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354462
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  • 6
    Electronic Resource
    Electronic Resource
    A Trinuclear Molybdenum Cluster Coordinated by o-Nitrobenzoate (1998)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 1612-1615 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S010827019800482X
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  • 7
    Electronic Resource
    Electronic Resource
    Pseudopotential approach to long period semiconductor superlattices
    Amsterdam : Elsevier
    Surface Science 228 (1990), S. 476-478 
    Details
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0039-6028(90)90356-D
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  • 8
    Electronic Resource
    Electronic Resource
    Luminescence centers in porous silicon (1995)
    Springer
    Applied physics 60 (1995), S. 601-606 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 82.40.Tc; 81.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract.  Photoluminescence studies on porous silicon show that there are luminescence centers present in the surface states. By taking photoluminescence spectra of porous silicon with respect to temperature, a distinct peak can be observed in the temperature range 100–150 K. Both linear and nonlinear relationships were observed between excitation laser power and the photoluminescence intensity within this temperature range. In addition, there was a tendency for the photoluminescence peak to red shift at low temperature as well as at low excitation power. This is interpreted as indicating that the lower energy transition becomes dominant at low temperature and excitation power. The presence of these luminescence centers can be explained in terms of porous silicon as a mixture of silicon clusters and wires in which quantum confinement along with surface passivation would cause a mixing of Γ and X band structure between the surface states and the bulk. This mixing would allow the formation of luminescence centers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01538535
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  • 9
    Electronic Resource
    Electronic Resource
    Luminescence centers in porous silicon (1995)
    Springer
    Applied physics 60 (1995), S. 601-606 
    Details
    ISSN: 1432-0630
    Keywords: 82.40.Tc ; 81.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Photoluminescence studies on porous silicon show that there are luminescence centers present in the surface states. By taking photoluminescence spectra of porous silicon with respect to temperature, a distinct peak can be observed in the temperature range 100–150 K. Both linear and nonlinear relationships were observed between excitation laser power and the photoluminescence intensity within this temperature range. In addition, there was a tendency for the photoluminescence peak to red shift at low temperature as well as at low excitation power. This is interpreted as indicating that the lower energy transition becomes dominant at low temperature and excitation power. The presence of these luminescence centers can be explained in terms of porous silicon as a mixture of silicon clusters and wires in which quantum confinement along with surface passivation would cause a mixing of Γ andX band structure between the surface states and the bulk. This mixing would allow the formation of luminescence centers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01538535
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  • 10
    Electronic Resource
    Electronic Resource
    Temperature effect on porous silicon luminescence (1994)
    Springer
    Applied physics 59 (1994), S. 227-231 
    Details
    ISSN: 1432-0630
    Keywords: 73.20.Dx ; 78.55.Hx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A theoretical surface-state model of porousilicon luminescence is proposed. The temperature effect on the PhotoLuminescence (PL) spectrum for pillar and spherical structures is considered, and it is found that the effect is dependent on the doping concentration, the excitation strength, and the shape and dimensions of the Si microstructure. The doping concentration has an effect on the PL intensity at high temperatures and the excitation strength has an effect on the PL intensity at low temperatures. The variations of the PL intensity with temperature are different for the pillar and spherical structures. At low temperatures the PL intensity increases in the pillar structure, while in the spherical structure the PL intensity decreases as the temperature increases, at high temperatures the PL intensities have a maximum for both models. The temperature, at which the PL intensity reaches its maximum, depends on the doping concentration. The PL spectrum has a broader peak structure in the spherical structure than in the pillar structure. The theoretical results are in agreement with experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348224
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