The chemical composition across strained layers was studied quantitatively by using analytical electron microscopy, energy-dispersive X-ray microanalysis, electron energy-loss spectroscopy, high-angle annular dark-field imaging and high-resolution electron microscopy. It was shown that the activation energy for the interdiffusion of the strained layers was 2.3eV. This was significantly lower than that for diffusion in bulk Si or SiGe. The measured interface widths were much larger than those predicted by a 2-state exchange model; thus suggesting that this model was an over-simplification. Increasing the growth temperature for chemical vapor deposition broadened the SiGe/Si interfaces asymmetrically. That is, a SiGe/Si interface was broadened much more than a Si/SiGe interface.

A quantitative study of compositional profiles in chemical vapor-deposited strained silicon-germanium/silicon layers T.Walther, C.J.Humphreys: Journal of Crystal Growth, 1999, 197[3], 113-28