Uniaxially stressed germanium with fundamental direct band gap

We demonstrate the crossover from indirect- to direct band gap in tensile-strained germanium by temperature-dependent photoluminescence. The samples are strained microbridges that enhance a biaxial strain of 0.16% up to 3.6% uniaxial tensile strain. Cooling the bridges to 20 K increases the uniaxial...

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Bibliographic Details
Published in:arXiv.org 2015-12
Main Authors: Geiger, R, Zabel, T, Marin, E, Gassenq, A, J -M Hartmann, Widiez, J, Escalante, J, Guilloy, K, Pauc, N, Rouchon, D, Diaz, G Osvaldo, Tardif, S, Rieutord, F, Duchemin, I, Y -M Niquet, Reboud, V, Calvo, V, Chelnokov, A, Faist, J, Sigg, H
Format: Article
Language:English
Subjects:
Band gap
Bowing
Crossovers
Energy gap
Photoluminescence
Temperature dependence
Tensile strain
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Summary:We demonstrate the crossover from indirect- to direct band gap in tensile-strained germanium by temperature-dependent photoluminescence. The samples are strained microbridges that enhance a biaxial strain of 0.16% up to 3.6% uniaxial tensile strain. Cooling the bridges to 20 K increases the uniaxial strain up to a maximum of 5.4%. Temperature-dependent photoluminescence reveals the crossover to a fundamental direct band gap to occur between 4.0% and 4.5%. Our data are in good agreement with new theoretical computations that predict a strong bowing of the band parameters with strain.
ISSN:2331-8422