Germanium under High Tensile Stress: Nonlinear Dependence of Direct Band Gap vs Strain

• DOI: 10.1021/acsphotonics.6b00429
• Publication Date: 2016-10-04T17:46:25Z
• Authors: Kevin Guilloy; Nicolas Pauc; Alban Gassenq; Yann-Michel Niquet; Jose-Maria Escalante; Ivan Duchemin; Samuel Tardif; Guilherme Osvaldo...; Denis Rouchon; Julie Widiez; Jean-Michel Hartmann; Richard Geiger; Thomas Zabel; Hans Sigg; Jerome Faist; Alexei Chelnokov; Vincent Reboud; Vincent Calvo
• Keywords: Hydrostatic pressure

Germanium is a strong candidate as laser source for silicon photonics. It widely accepted that the band structure of germanium can be altered by tensile strain so to reduce energy difference between its direct and indirect gaps. However, conventional gap deformation potential model most adopted describe this transition happens have been investigated only up 1% uniaxially loaded strains. In work, we use microbridge geometry stress along [100] ε100 = 3.3% longitudinal then perform electroabsorption spectroscopy. We accurately measure conduction at Γ point light- heavy-hole valence bands calculate theoretical dependency using tight-binding model. hydrostatic tetragonal shear −9.1 ± 0.3 eV b −2.32 0.06 introduce second-order provides better fit both experimental relations. These new high-strain coefficients will suitable design future CMOS-compatible lasers optoelectronic devices based on highly strained germanium.