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  • 1
    Electronic Resource
    Electronic Resource
    Exchange in II-VI-based magnetic semiconductors (invited) (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5084-5089 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a physically oriented survey of exchange constants among Mn local moments, and between Mn moments and sp band electrons in II-VI-based magnetic semiconductors (MS) such as Cd1−xMnxTe. A simple three-site model illustrates the physical principles underlying our quantitative calculations of Mn-Mn exchange based on a semiempirical tight-binding Anderson model. Superexchange interactions, computed perturbatively in the Mn d-sp band hybridization, are the dominant mechanisms of isotropic and anisotropic Mn-Mn exchange. The Dzyaloshinsky–Moriya (DM) anisotropic superexchange constant D has a magnitude of ∼5% of the isotropic superexchange constant J. The DM exchange explains spin resonance linewidths and the nature of short range spin ordering in the magnetically concentrated regime. The contribution of anistropic Mn-sp band exchange is also considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344681
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  • 2
    Electronic Resource
    Electronic Resource
    Superlattice excitons and optical absorption (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 7369-7378 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A formalism based on the superlattice crystal coordinate representation, which is valid for arbitrary well and barrier widths, is developed and applied to the Wannier exciton problem. A simple model for the electron-hole Coulomb interaction within the independent subband approximation permits nonvariational calculation of exciton binding energies, oscillator strengths, and optical absorption of both bound and continuum exciton states. The effects of growth axis directed electric and magnetic fields are emphasized. Numerical results for GaAs/ Ga1−xAlxAs and In1−xGaxAs/GaAs exciton binding energies and oscillator strengths as functions of well width, barrier width, and electric and magnetic field strengths show excellent agreement with experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355005
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  • 3
    Electronic Resource
    Electronic Resource
    Induced electric fields in anisotropic thermoelectric materials (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 5065-5069 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transport in an anisotropic material can create potentially large induced transverse fields which reduce the measured electric and thermal conductivities relative to those computed without the induced fields. These affect the thermoelectric figure of merit ZT modestly. The induced electric field in n-type Bi2Te3 is predicted to be as much as 76% of the external one and can lower the measured electrical conductivity by up to 60%. In Hg1−xCdxTe superlattices, the anisotropy may be increased by varying the composition and width of the barrier and well to give induced fields much larger than the applied one. These effects should be easily observable. The present work utilizes general results applied to a microscopic model relevant for multivalleyed materials within the effective-mass and relaxation-time approximations. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371480
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  • 4
    Electronic Resource
    Electronic Resource
    Theoretical performance limits of 2.1–4.1 μm InAs/InGaSb, HgCdTe, and InGaAsSb lasers (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 4552-4559 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ideal threshold current densities of 2.1–4.1 μm IR lasers are calculated for active layers composed of InAs/InGaSb superlattices, InGaAsSb quantum well quaternaries, InAsSb bulk ternaries, and HgCdTe superlattices. The fully K-dependent band structure and momentum matrix elements, obtained from a superlattice K⋅p calculation, are used to calculate the limiting Auger and radiative recombination rates and the threshold current density. InGaAsSb quantum wells and InAs/InGaSb superlattices are found to be more promising laser candidates than HgCdTe superlattices and InAsSb bulk ternaries. The calculated threshold current densities of InAs/InGaSb superlattices are similar to those of InGaAsSb active layers at 2.1 μm, but are significantly lower at longer wavelengths. Comparison with experiment indicates that the threshold current densities of InGaAsSb-based devices are about three times greater than those calculated for 25 cm−1 gain. The threshold current densities of present InAs/InGaSb superlattices are about 100 times above their theoretical limit. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359798
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  • 5
    Electronic Resource
    Electronic Resource
    Long wavelength InAs/InGaSb infrared detectors: Optimization of carrier lifetimes (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 7143-7152 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The performance characteristics of type-II InAs/InxGa1−xSb superlattices for long and very long-wave infrared detection are discussed. This system promises benefits in this wavelength range over conventional technology based on Hg1−xCdxTe, in part because of suppressed band-to-band Auger recombination rates which lead to improved values of detectivity. The formalism for calculating Auger rates in superlattices is developed and the physical origin of Auger suppression in these systems is discussed. Accurate K⋅p band structures are used to obtain radiative, electron–electron, hole–hole, and band-to-band Auger rules, as well as shallow trap level assisted Auger recombination rates for photodiodes. Theoretical limits for high temperature operation of ideal photovoltaic detectors are presented and compared with HgCdTe. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360422
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  • 6
    Electronic Resource
    Electronic Resource
    Theoretical performance of InAs/ InxGa1−xSb superlattice-based midwave infrared lasers (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 1940-1942 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show that for appropriate layer widths the performance of ideal InAs/InxGa1−xSb superlattice-based midwave injection lasers can be limited by radiative rather than Auger recombination. The threshold carrier densities and lifetimes are calculated over the 77–300 K temperature range at 3.5 μm. Lifetimes are obtained from detailed calculations of band-to-band Auger and radiative recombination rates based on realistic nonparabolic band structures. This system is therefore a promising new laser candidate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357682
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  • 7
    Electronic Resource
    Electronic Resource
    Reply to "Comment on ‘Temperature limits on infrared detectivities of InAs/InxGa1−xSb superlattices and bulk Hg1−xCdxTe' '' [J. Appl. Phys. 80, 2542 (1996)] (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2545-2546 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Despite the preceding Comment's assertions, the maximum theoretical detectivities of LWIR InAs/InGaSb superlattices are greater than those of HgCdTe provided the comparison involves the same base layer thicknesses (greater than the minority carrier diffusion length). The higher optimal doping of the superlattices relative to HgCdTe results in noise suppression. It is desirable because Auger recombination is substantially depressed. Shockley–Van Roosbroeck optical recombination and hence photon recycling is of little consequence in realistic device structures. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363044
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  • 8
    Electronic Resource
    Electronic Resource
    Reply to "Comment on ‘Temperature limits on infrared detectivities of InAs/InxGa1−xSb superlattices and bulk Hg1−xCdxTe' '' [J. Appl. Phys. 74, 4774 (1993)] (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 4156-4158 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Our calculations of the relative performance of ideal superlattice and HgCdTe (MCT) photovoltaic long wave infrared detectors, criticized in the previous Comment, do include radiative lifetimes. They also find the Auger-7 lifetime to be shorter than the radiative lifetime for p doping levels of 1017 cm−3. This agrees with other calculations and with the majority of experiments. The issue of detector thickness raised in the comment is not relevant since neither MCT nor the superlattices has an intrinsic advantage in this respect. The superlattices are further favored relative to MCT by lower tunneling currents, higher uniformity, and materials processing advantages. We suggest the superlattice system to be promising for the eventual realization of high-performance detectors. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359528
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  • 9
    Electronic Resource
    Electronic Resource
    Theoretical performance of wurtzite and zincblende InGaN/GaN quantum well lasers (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2087-2089 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The theoretical gain, radiative and Auger recombination rates, and threshold current densities of ideal wurtzite (WZ) and zincblende (ZB) 20 Å In0.2Ga0.8N/70 Å GaN multiple quantum well laser diodes are compared. We obtain upper bounds on device performance, which are based on reliable calculations for both band structure and recombination dependent features and show (1) that the performance of present devices having the ZB and WZ structures are within 20% of each other in InGaN/GaN, and (2) that present performance of the best currently available devices is only a factor of 3–4 below the theoretical limit. Radiative recombination is far more important than Auger processes. The calculations are performed using a superlattice K⋅p formalism and density functional theory within the local-density approximation. The latter yields bulk zone-center energies, wave functions, and directly calculated momentum matrix elements. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122386
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  • 10
    Electronic Resource
    Electronic Resource
    Carrier-activated light modulation (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 180-181 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A variety of superlattices is predicted to exhibit high-speed carrier-activated light modulation. The proposal is based on the large, tunable, and very narrow absorption peak for transitions between the two lowest conduction subbands. The theory, which is demonstrated to be predictive, also suggests correspondingly large variations of the refractive index.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100167
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