Published online by Cambridge University Press: 10 February 2011
Si1-xGex/Si heterostructures with different layer thicknesses grown by selective LPCVD epitaxy at different growth temperatures were investigated with regard to plastic relaxation. AFM and optical micrograph were performed to determine the dislocation density. From the analysis of the misfit dislocations at the initial stage of relaxation of the samples grown at 700°C it was possible to determine the nucleation site density and an activation energy of 2.8 eV for the heterogeneous nucleation of misfit dislocations. While the critical thickness hc for a given Ge content increases with decreasing growth temperature between 800°C-680°C one observes a dramatic decay of hc, at a growth temperature of 625°C. For growth at 625°C it was found that this activation barrier is drastically decreased.