Diffusion phenomena in MBE grown SiSiGe single quantum wells studied by PL and TEM measurements

MBE grown SiSiGe single quantum wells with a nominal well width of 4 nm and a Ge concentration of 20% were analyzed by photoluminescence techniques and transmission electron microscopy. As-grown and post-growth annealed samples were compared in order to study individually interdiffusion phenomena at the SiSiGe heterointerface. The spectral distribution of the SiGe-related emissions remains constant for samples grown at substrate temperatures lower than approximately 850°C, whereas a further increase of the growth temperature causes a substantial blue shift. From a comparison between as-grown and annealed samples it is shown that the main contribution to this energy shift is due to interdiffusion of Si and Ge at the heterointerfaces.