Single quantum wells, with a nominal width of 4nm and a Ge concentration of 20%, were prepared by means of molecular beam epitaxy. They were then studied by using photoluminescence and transmission electron microscopic techniques. As-grown and annealed samples were compared in order to monitor individual diffusion phenomena at the Si/SiGe interface. It was found that the spectral distribution of the SiGe-related emissions remained constant for samples which were grown at substrate temperatures of less than 850C. A further increase in the growth temperature produced an appreciable blue shift. It was concluded that the main contribution to this energy shift was the interdiffusion of Si and Ge at the hetero-interface.

H.P.Zeindl, S.Nilsson, E.Bugiel: Applied Surface Science, 1996, 92, 552-6