INFLUENCE OF ANNEALING ON THE INTERFACE STRUCTURE AND STRAIN RELIEF IN SI GE HETEROSTRUCTURES ON (100) SI/

Research work on the general problem of the nature and thermal stabili ty of the Si/Ge semiconductor interface is reviewed. We report on our recent studies of the interface structure in [(Si)(m)(Ge)(n)](p) super lattices and (Ge)(n) layers buried in Si as revealed by Raman scatteri ng, extended X-ray absorption fine structure, and X-ray techniques. St rain relaxation and interdiffusion in the superlattices caused by anne aling have been investigated, and it is found that considerable strain -enhanced intermixing together with partial relaxation of Ge-Ge bonds occurs even for very short anneal times at 700 degrees C. Further anne aling leads to diffusion at a much slower rate and to the eventual for mation of an alloy layer. The Ge-Ge bond lengths in as-grown samples a re that expected for a fully strained Ge layer. Similar studies of the (Ge)(n) layers reveal that two-dimensional pseudomorphic growth proce eds up to n = 5, probably mediated by a Si-Ge interface interdiffusion over one or two monolayers of approximately 20%. A n = 12 layer gave evidence of strain relaxation by the introduction of dislocations and clustering. Interdiffusion proceeds rapidly on annealing at 750 degree s C.