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  • 1
    Electronic Resource
    Electronic Resource
    Mott ionization of excitons in n-type Zn1−xMnxSe epilayers (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3150-3152 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recently, the first controlled n-type doping of Zn1−xMnxSe epilayers was reported. Using time-resolved photoluminescence we show that exciton ionization in the moderately doped samples occurs at a significantly lower temperature (50 K) than in undoped material (180 K). This behavior is consistent with Mott ionization of excitons from the increased majority carrier density at higher temperatures. The density and temperature at which the ionization occurs are estimated using calculations of the Mott density and the density-dependent exciton binding energy. No excitons are observed down to 2 K in the samples, which were doped at the highest densities, suggesting that these samples were degenerately doped. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115145
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  • 2
    Electronic Resource
    Electronic Resource
    Photoluminescence quenching in Si1−xGex/Si multiple quantum wells grown with atomic hydrogen (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 2875-2880 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We compare the photoluminescence spectra from a series of Si1−xGex/Si (0.1≤x≤0.3) multiple quantum well (MQW) samples grown with atomic hydrogen to a series of similar samples grown without atomic hydrogen. All of the samples were grown at 710 °C. We observe intense quantum confined photoluminescence in the Si1−xGex/Si MQW samples grown without atomic hydrogen. No quantum confined photoluminescence was observed in the Si1−xGex/Si MQW samples grown with atomic hydrogen. This was unexpected, since quantum confined photoluminescence has been observed in the hydrogen-assisted growth of Si1−xGex/Si quantum well structures grown at lower temperatures by other researchers. We believe that this is caused by defects, introduced into the samples during growth with atomic hydrogen, which lead to efficient nonradiative centers that compete with the radiative centers. These defects lead to a reduction of the photoluminescence of the samples grown with atomic hydrogen. Since hydrogen is used as a surfactant to reduce the deleterious effects due to Ge segregation, understanding its role is an important step in SiGe materials development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369632
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis, processing, and third-order nonlinear optical properties of benzobisthiazole polymers containing thiophene moieties (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 723-729 
    Details
    ISSN: 0887-624X
    Keywords: benzobisthiazole ; nonlinear optical ; thiophene ; degenerate four-wave mixing ; bithiophene ; terthiophene ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Benzobisthiazole polymers containing mono-, bi-, and terthiophene moieties were synthesized through polycondensation in polyphosphoric acid of 2,5-diamino-1,4-benzenedithiol dihydrochloride with thiophene-2,5-dicarboxylic acid, 2,2′-bithiophene-5,5′-dicarboxylic acid, and 2,2′:5′,2″-terthlophene-5,5″-dicarboxylic acid, or their corresponding diacid chlorides, respectively. Intrinsic viscosities of up to 8.1 dL/g (methanesulfonic acid, 30°C) were recorded. Polymer structures were verified by elemental analysis and spectroscopic comparison of the polymers with appropriate model compounds. Onset of breakdown under thermogravimetric analysis in air occurred in the 460-590°C range with the benzobisthiazole polymers containing a monothiophene linkage being the most stable. Films suitable for third-order optical susceptibility measurements could be prepared by extrusion techniques from the benzobisthiazole polymer containing a monothiophene linkage. Degenerate four wave mixing measurements on this film yielded a third order optical susceptibility χ(3) of approximately 4.5 × 10-10 esu. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310317
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