The photoluminescence from high-quality relaxed Si1-xGex pseudo-substrates, which had been grown by rapid thermal chemical vapor deposition, was studied. The samples consisted of Si1-xGex relaxed capping layers with x = 0.32 or 0.52, and a composition-gradient SiGe buffer layer. The composition gradient was shown to play a governing role in determining layer quality. The spectra revealed well-resolved band-edge photoluminescence which originated from the relaxed alloy capping layer, and defect-related bands which were associated with dislocations in the buffer gradient layer. A detailed analysis of the dislocation bands demonstrated that the main misfit dislocations remained confined to the gradient buffer layer. Well-defined photoluminescence results which were obtained for SiGe layers that had been grown, under compressive and tensile strains, onto these pseudo-substrates were explained in terms of strain symmetrization and the high quality of the layers.

G.Bremond, A.Souifi, O.De Barros, A.Benmansour, P.Warren, D.Dutartre: Journal of Crystal Growth, 1995, 157[1-4], 116-20