Photoluminescence of hydrogenated Si_mGe_n superlattices

The effect of hydrogen passivation on the photoluminescence of Si-rich superlattices is investigated. The as-grown samples show many defect-related luminescence signals and several additional luminescence peaks believed to originate from the superlattice. The background luminescence along with the dislocation and defect lines are found to be passivated by the hydrogen atoms. The intensity of the superlattice peak increases after passivation and its phonon replica, initially submerged in the background and defect luminescence signals, is highlighted. After a subsequent temperature annealing in N ₂, the background luminescence is increased as hydrogen outdiffuses but the superlattice main peak decreases, perhaps due to the change of the carrier lifetime.