Influence of the Si–Ge interface on phononless radiative recombination in Ge hut clusters grown on Si (0 0 1)

Intense photoluminescence (PL) is observed from Ge hut clusters grown by molecular beam epitaxy on Si (001). Phononless radiative recombination results from three-dimensional carrier confinement of electrons in the surrounding tensile-strained Si and holes within the Ge hut. Post-growth annealing experiments reveal that enhanced phononless PL is due to localization of carriers at the embedded hut clusterʹs interface. A simple model is presented which explains the enhanced PL in terms of wave function overlap of the carriers confined in the type-II band alignment.