Uniaxially stressed germanium with fundamental direct band gap

R. Geiger; T. Zabel; E. Marin; A. Gassenq; J. -M. Hartmann; J. Widiez; J. Escalante; K. Guilloy; N. Pauc; D. Rouchon; G. Osvaldo Diaz; S. Tardif; F. Rieutord; I. Duchemin; Y. -M. Niquet; V. Reboud; V. Calvo; A. Chelnokov; J. Faist; H. Sigg

arXiv · 1603.03454

Uniaxially stressed germanium with fundamental direct band gap

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Abstract

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.

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R. Geiger, T. Zabel, E. Marin, A. Gassenq, J. -M. Hartmann, J. Widiez, J. Escalante, K. Guilloy, N. Pauc, D. Rouchon, G. Osvaldo Diaz, S. Tardif, F. Rieutord, I. Duchemin, Y. -M. Niquet, V. Reboud, V. Calvo, A. Chelnokov, J. Faist, H. Sigg. 2015-12-10. Uniaxially stressed germanium with fundamental direct band gap. https://arxiv.org/abs/1603.03454

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