Tensile-strained direct bandgap GeSnOI micro/nanostructures by harnessing residual strain

Combining Sn alloying and tensile strain to Ge has emerged as the most promising engineering approach to create an efficient Si-compatible lasing medium. The residual compressive strain in GeSn has thus far made the simple geometrical strain amplification technique unsuitable for achieving tensile strained GeSn. Herein, by utilizing two unique techniques, we report the introduction of a uniaxial tensile strain directly into GeSn micro/nanostructures. By converting GeSn from indirect to direct bandgap material via tensile strain, we achieve a 10-fold increase in the light emission intensity.