The role of a low-temperature Si buffer layer during the plastic relaxation of molecular-beam epitaxy grown GeSi/Si(001) was studied. Probable sources and mechanisms of generation of misfit dislocations were considered. Transmission electron microscopic and X-ray diffraction techniques were used for studying 100nm GexSi1–x films with low-temperature Si and those free of such a buffer layer. The misfit dislocation density was found to be much lower in the former than in the latter, and the level of the film plastic relaxation was not higher than 20% in both as-grown and annealed films with low-temperature Si. As the thickness of the solid solution layer reached 300 to 400nm, the plastic relaxation of the films increased to almost 100%. Therefore, a determining role of the misfit dislocation multiplication was assumed. A double role was assumed for the low-temperature Si buffer layer. First, the diffusion flux of vacancies from the low-temperature Si layer to the GeSi/Si interface may cause erosion of the interface and, as a result, a decrease in the rate of misfit dislocation generation at the early stages of epitaxy. Second, generation of intrinsic defect clusters in the low-temperature Si, which were potential sources of misfit dislocations, occurred in the field of mechanical stresses of the growing pseudomorphic layer. This process was thought to be the key feature of the plastic relaxation of GeSi/LT-Si/Si(100) films which promotes misfit dislocation self-organization.

Plastic Relaxation of Solid GeSi Solutions Grown by Molecular-Beam Epitaxy on the Low Temperature Si(100) Buffer Layer. Y.B.Bolkhovityanov, A.K.Gutakovskii, V.I.Mashanov, O.P.Pchelyakov, M.A.Revenko, L.V.Sokolov: Journal of Applied Physics, 2002, 91[7], 4710-4