The development of efficient silicon-based light emitting devices is a challenging task in modern semiconductor physics and optoelectronics. Due to the indirect nature of the band gap, bulk silicon has a poor luminescence. One of the promising approaches to increase the luminescence efficiency of Si-based materials is to apply the concept of incorporating of nanostructures into the Si matrix. Our approach at MPI-Halle is related to the generation of nanostructures in the silicon matrix, which intensively emit light in the near-infrared range at room temperature. As a growth technique, molecular-beam epitaxy (MBE) is applied. The following topics include basic research on growth phenomena as well as on optical transitions in nanostructures. Silicon-germanium superlattices are promising candidates for a technological application.