STRUCTURAL CHARACTERIZATION OF SI GE SUPERLATTICES GROWN ON AN SI(001) SURFACE BY MOLECULAR-BEAM EPITAXY/

Structural quality of (SimGen)(N) superlattices grown on an Si(001)-2 x 1 surface at different temperatures (300-500 degrees C) by molecular beam epitaxy was characterized by reflection high energy electron dif fraction, X-ray diffraction, Raman scattering and high-resolution tran smission electron microscopy. Asymmetric intermixing is observed, in w hich the Si-on-Ge interface is less abrupt than the Ge-on-Si interface due to Ge segregation into the growing Si overlayer. It is found that the degree of intermixing and crystalline quality depends on the grow th temperature. Experimental evidence shows that significant intermixi ng due to thermal diffusion of Ge atoms into the growing Si layers occ urs at 500 degrees C.