Heterostructures on Si-on-sapphire substrates were grown epitaxially by using ultra-high vacuum chemical vapor deposition. High-resolution triple-axis X-ray diffraction was used to analyze the structures and their thermal stability. Out-diffusion of Ge from the strained SiGe quantum well was observed after annealing at 850C. The degree of out-diffusion was comparable to that observed in SiGe structures on bulk Si wafers.

X-ray diffraction analysis of SiGe/Si heterostructures on sapphire substrates P.M.Mooney, J.A.Ott, J.O.Chu, J.L.Jordan-Sweet: Applied Physics Letters, 1998, 73[7], 924-6