Time-resolved photoluminescence of pseudomorphic SiGe quantum wells

We report low-temperature time-resolved photoluminescence experiments on a pseudomorphic SiGe quantum-well structure. Under the condition of optical absorption in the Si buffer layers, the decay time of the SiGe quantum-well luminescence is controlled by the capture of excitons and electron-hole droplets. From the onset of the SiGe luminescence, the exciton lifetime in the investigated 59-\AA{}-wide ${\mathrm{Si}}_{0.72}$${\mathrm{Ge}}_{0.28}$ quantum wells is found to be about 100 ns.