The growth of heterostructures was studied by using a chemical vapour deposition cold-wall vertical reactor, with SiH4 and GeH4 gaseous precursors, and ultra-high vacuum or low-pressure regimes. The latter regime was suitable for preparing thick, gradually relaxed, Si0.75Ge0.25/Si pseudo-substrates. The optimum grading rate of 10%Ge/μm led to a 5nm root-mean-square surface roughness and threading dislocation densities which were as low as 103/cm2. These values could be improved by using thin layers of pure Si as dislocation filters.

Chemical Vapour Deposition of Silicon-Germanium Heterostructures. S.Bozzo, J.L.Lazzari, C.Coudreau, A.Ronda, F.A.d'Avitaya, J.Derrien, S.Mesters, B.Hollaender, P.Gergaud, O.Thomas: Journal of Crystal Growth, 2000, 216[1-4], 171-84