Room temperature photoluminescence of tensile-strained Ge/Si_0.13Ge_0.87 quantum wells grown on silicon-based germanium virtual substrate

We report a room temperature study of the direct band gap photoluminescence of tensile-strained Ge/Si_0.13Ge_0.87 multiple quantum wells grown on Si-based germanium virtual substrates by ultrahigh vacuum chemical vapor deposition. Blueshifts of the luminescence peak energy from the Ge quantum wells in comparison with the Ge virtual substrate are in good agreement with the theoretical prediction when we attribute the luminescence from the quantum well to the cΓ1-HH1 direct band transition. The reduction in direct band gap in the tensile strained Ge epilayer and the quantum confinement effect in the Ge/Si_0.13Ge_0.87 quantum wells are directly demonstrated by room temperature photoluminescence.