Determination of the optical energy gap of Ge1−xSnx alloys with 0<x<0.14

The optical energy gap of Ge1−xSnx alloys has been determined from transmittance measurements, using a fast-Fourier-transform infrared interferometer. Our results show that the change from indirect to direct band gap occurs at a lower critical Sn concentration (xc) than the value predicted from the...

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Bibliographic Details
Published in:Applied physics letters 2004-05, Vol.84 (22), p.4532-4534
Main Authors: Ladrón de Guevara, H. Pérez, Rodrı́guez, A. G., Navarro-Contreras, H., Vidal, M. A.
Format: Article
Language:English
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Summary:The optical energy gap of Ge1−xSnx alloys has been determined from transmittance measurements, using a fast-Fourier-transform infrared interferometer. Our results show that the change from indirect to direct band gap occurs at a lower critical Sn concentration (xc) than the value predicted from the virtual crystal approximation, tight binding, and pseudopotential models. However, a close agreement between the experimental results and the predictions with deformation potential theory is observed. The concentration xc, which is theoretically expected to be 0.09, actually it is observed to lie between 0.10
ISSN:0003-6951
1077-3118
DOI:10.1063/1.1758772