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  • 2000-2004  (53)
  • 1
    Electronic Resource
    Electronic Resource
    Band gaps, effective masses and refractive indices of PbSrSe thin films: Key properties for mid-infrared optoelectronic device applications (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 192-198 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Key properties of PbSrSe thin films grown by molecular beam epitaxy have been studied for mid-infrared optoelectronic device applications. Detailed knowledge of the material parameters for the device design is required. The material parameters considered are: temperature-dependent band gaps, composition (or band gap)-dependent effective masses, and energy-dependent refractive indices. The study has been carried out by a combination of temperature-dependent photoluminescence and absorption measurements with the theoretical models on PbSrSe thin films of Sr compositions of as high as 0.276. The derived empirical equations for band gaps, effective masses, and refractive indices have been employed successfully in PbSe/Pb0.934Sr0.066Se multiple quantum well mid-infrared laser systems, for studying the band offsets and subband behavior. We have shown that the derived material parameters clearly promise of being applied to other PbSrSe thin films and PbSe/PbSrSe heterostructure systems for their optoelectronic applications. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1421634
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  • 2
    Electronic Resource
    Electronic Resource
    Excitonic line broadening in PbSrSe thin films grown by molecular beam epitaxy (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 3621-3625 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pb1−xSrxSe thin films grown by molecular beam epitaxy have been investigated by x-ray diffraction and temperature-dependent photoluminescence measurements with the Sr composition as high as 0.276. Temperature and composition dependent excitonic line broadening effects in PbSrSe thin films have been studied on the basis of the proposed theoretical models and the experimentally obtained lattice constant, excitonic energy gap and effective mass as a function of the alloy composition. The exciton-longitudinal optical phonon coupling model has been employed successfully for PbSrSe with a coupling strength of 51.0 meV, which can be well explained by the proposed theoretical approach. The lattice deformation may have played a key role in the composition dependent broadening in PbSrSe at low temperature, rather than the normally observed alloy disorder effect in III–V and II–VI semiconductor materials. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1448897
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  • 3
    Electronic Resource
    Electronic Resource
    Radiative recombination characteristics in GaAs multilayer n+−i interfaces (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 5444-5446 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this communication, we have carried out a detailed investigation of radiative recombination in n-GaAs homojunction far-infrared detector structures with multilayer emitter (n+)-intrinsic (i) interfaces by temperature-dependent steady-state photoluminescence measurements. The observation of the emitter-layer luminescence structures has been identified from their luminescence characteristics, in combination with high density theoretical calculation. A photogenerated carrier transferring model has been proposed, which can well explain the dependencies of the luminescence intensities on the laser excitation intensity and temperature. Furthermore, the obtained radiative recombination behavior helps us to offer a proposal to improve the operating temperature of the detector. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1405137
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  • 4
    Electronic Resource
    Electronic Resource
    Free-carrier absorption in Be- and C-doped GaAs epilayers and far infrared detector applications (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 3295-3300 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Far infrared (FIR) absorption, reflection, and transmission in heavily doped p-GaAs multilayer structures have been measured for wavelengths 20–200 μm and compared with the calculated results. Both Be (in the range 3×1018–2.6×1019 cm−3) and C (1.8×1018–4.7×1019 cm−3)-doped structures were studied. It is found that the observed absorption, reflection, and transmission are explained correctly by the model with a dominant role of free-carrier absorption in highly doped regions. High reflection from heavily doped thick layers is attractive for the resonant cavity enhanced FIR detectors. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1347002
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  • 5
    Electronic Resource
    Electronic Resource
    Bandtail characteristics in InN thin films (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 2063-2065 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Urbach bandtail characteristics in InN thin films grown by radio-frequency magnetron sputtering on sapphire (0001) substrates have been investigated both theoretically and experimentally. The bandtail parameter in InN thin films has been obtained by temperature-dependent transmission spectra, with the aid of a detailed calculation of the transmission profile. A bandtail model based on the calculation of density of occupied states and the carrier–phonon interaction has been employed to analyze the temperature-dependent bandtail characteristics. The bandtail parameter is in the range of 90–120 meV in the InN thin film. It is found that the carrier–phonon interaction in InN is weak and the structural disorder contribution (∼90 meV) dominates over the interactive terms. The high structural disorder in InN thin films may relate to the high nonradiative recombination centers. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1464219
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  • 6
    Electronic Resource
    Electronic Resource
    Study of exciton–longitudinal optical phonon coupling in quantum wells for optoelectronic applications (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 1285-1287 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The study of exciton–longitudinal optical (LO) phonon coupling in semiconductor quantum well (QW) structures and their corresponding bulk materials reveals four distinct features: a large difference between (i) III–V and II–VI QW structures, (ii) multiple QW and single QW structures, as well as (iii) QW structures and their corresponding bulk materials, and its linear dependence on well width in QW structures. A quantitatively theoretical approach is presented, which can explain well all the experimental observations and can clarify the controversy in the literature. The effects of alloy disorder and strain in QW structures on exciton–LO phonon coupling are also discussed. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1392306
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  • 7
    Electronic Resource
    Electronic Resource
    Study of band structure in PbSe/PbSrSe quantum wells for midinfrared laser applications (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 2579-2581 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electronic states in PbSe/Pb0.934Sr0.066Se multiple-quantum-well structures (MQWs) grown by molecular-beam epitaxy have been investigated both theoretically and experimentally for the midinfrared laser applications. With the aid of combined temperature-dependent photoluminescence and absorption measurements on a Pb0.934Sr0.066Se thin film for the effective masses and temperature-dependent band gaps, we find that the PbSe/PbSrSe MQWs have type-I band alignment and the conduction band offset ratio is Qc=0.82±0.03. The calculation, taking into account the strain, carrier confinements, and the multivalley band structure, can well explain both the observed luminescence peak energies and the temperature coefficient of the luminescence peaks as a function of well thickness. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1406988
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  • 8
    Electronic Resource
    Electronic Resource
    Study on the quantum efficiency of resonant cavity enhanced GaAs far-infrared detectors (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5538-5544 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a detailed theoretical analysis on the quantum efficiency of a resonant cavity enhanced (RCE) GaAs homojunction work function internal photoemission far-infrared (FIR) detector. The quantum efficiency under both resonant and nonresonant conditions has been calculated. All the detector parameters are optimized under the realistically nonresonant condition. The further investigation of the standing wave effect (SWE) shows that the SWE is important and cannot be neglected for the FIR detector. The resulting quantum efficiency is about two times higher than that in the normal GaAs homojunction FIR detector measured by experiment, showing a promising effect. In contrast to the case in the near-infrared region, the wavelength selectivity is not obvious in the FIR region. The theoretical analysis can be applied to other RCE homojunction FIR detectors. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1465513
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  • 9
    Electronic Resource
    Electronic Resource
    Thermodynamic properties of an alternating-spin (1/2,1) two-leg ladder (2003)
    Springer
    The European physical journal 37 (2003), S. 169-175 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. With the aid of the Schwinger-boson mean-field method, we study the low-lying excitations and thermodynamic properties of a ferrimagnetic Heisenberg two-leg ladder (i.e., a ferrimagnetic double-chain with an antiferromagnetic interaction). The interaction between the two chains plays an important role in producing a low-lying excitation energy gap, affecting the low-lying excited spectrum, and increasing the disorder of the ferrimagnetic double-chain. The excitation spectrum, energy gap, and spin reduction in the ground state are calculated. Thermodynamic quantities such as the short-range spin correlation and short-range order are also obtained at low temperatures. In this gapful system, we observed the exponential behaviors in both the specific heat (C V ) and the product of magnetic susceptibility and temperature ( $\chi T$ ) at low temperatures. The exponential behavior of the $\chi T$ versus temperature agrees qualitatively with the experimental results in $\rm NiCu(pba)(D_2O)_3\cdot D_2O$ at low temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2004-00043-y
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  • 10
    Electronic Resource
    Electronic Resource
    Recent Progress in Mid- and Far-Infrared Semiconductor Detectors (2000)
    Springer
    International journal of infrared and millimeter waves 21 (2000), S. 1739-1746 
    Details
    ISSN: 1572-9559
    Keywords: progress ; infrared ; semiconductor detector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The recent developments of semiconductor infrared detectors in extending the wavelength coverage and improving the focal plane array (FPA) performance are reviewed. The emphasis is on the GeSi/Si heterojunction infrared photoemission detectors (HIPs), GaAs/AlGaAs quantum well infrared photodetecots (QWIPs), Si, Ge and GaAs blocked impurity band detectors (BIBS), and Si and GaAs homojunction interfacial work-function internal photo-emission (HIWIP) far-infrared (FIR) detectors. The advantages, current status, and potential limitations of these infrared detectors have also been discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006758500042
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