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Photoluminescence spectroscopy has been used to determine the direct gap E0 of Ge1-ySny alloys over a broad compositional range from pure Ge to Sn concentrations exceeding 10%. A fit of the compositional dependence of E0 using a standard quadratic expression…

Photoluminescence spectroscopy has been used to determine the direct gap E0 of Ge1-ySny alloys over a broad compositional range from pure Ge to Sn concentrations exceeding 10%. A fit of the compositional dependence of E0 using a standard quadratic expression is not fully satisfactory, revealing that the bowing parameter (quadratic coefficient) b0 is compositionally dependent. Excellent agreement with the data is obtained with b0(y) = (2.66 ± 0.09) eV − (5.4 ± 1.1)y eV. A theoretical model of the bowing is presented, which explains the strong compositional dependence of the bowing parameter and suggest a similar behavior for the indirect gap. Combining the model predictions with experimental data for samples with y ≤ 0.06, it is proposed that the bowing parameter for the indirect gap is bind(y) = (1.11 ± 0.07) eV − (0.78 ± 0.05)y eV. The compositional dependence of the bowing parameters shifts the crossover concentration from indirect to direct gap behavior to yc  = 0.087, significantly higher than the value predicted earlier based on strictly quadratic fits.

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    Title
    • Compositional Dependence of the Bowing Parameter for the Direct and Indirect Band Gaps in Ge1-ySny Alloys
    Contributors
    Date Created
    2014-10-06
    Resource Type
  • Text
    • Collections this item is in
    ASU Scholarship Showcase
    Identifier
    • Digital object identifier: 10.1063/1.4897272
    • International standard serial number
      0003-6951
    • International standard serial number
      1077-3118
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    • Copyright 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. along with the following message: The following article appeared in 105, 14 (2014) and may be found at http://dx.doi.org/10.1063/1.4897272

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    Gallagher, J. D., Senaratne, C. L., Kouvetakis, J., & Menendez, J. (2014). Compositional dependence of the bowing parameter for the direct and indirect band gaps in Ge1-ySny alloys. APPLIED PHYSICS LETTERS, 105(14), 0-0. http://dx.doi.org/10.1063/1.4897272

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