DIFFUSION PHENOMENA IN MBE GROWN SI SIGE SINGLE QUANTUM-WELLS STUDIEDBY PL AND TEM MEASUREMENTS/

MBE grown Si/SiGe single quantum wells with a nominal well width of 4 nm and a Ge concentration of 20% were analyzed by photoluminescence te chniques and transmission electron microscopy. As-grown and post-growt h annealed samples were compared in order to study individually interd iffusion phenomena at the Si/SiGe heterointerface. The spectral distri bution of the SiGe-related emissions remains constant for samples grow n at substrate temperatures lower than approximately 850 degrees C, wh ereas a further increase of the growth temperature causes a substantia l 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.