DIFFUSION MECHANISMS IN SiGe ALLOYS

摘要

Interest in SiGe alloys for HBT's, HFET's and optoelectronic devices, has highlighted the lack of knowledge of diffusion processes in this material. Self-diffusion studies are first reviewed, and early Ge isotope diffusion studies in bulk material indicated a changeover in diffusion mechanism in the 65-35 Si-Ge alloy region from the accepted monovacancy self-diffusion mechanism in germanium. More recent studies of dopant diffusion in epitaxial Si-Ge layers point to a similar changeover in mechanism in the case of boron, a useful p-type dopant. Studies of antimony diffusion, which appears to diffuse by the vacancy mechanism in both silicon and germanium, are furnishing important information on vacancy diffusion processes in the alloy. Priorities for further work are suggested.