Quantitative analysis of strain relaxation in GexSi1−x/Si(110) heterostructures and an accurate determination of stacking fault energy in GexSi1−x alloys

Abstract

We report a quantitative theoretical and experimental analysis of strain relaxation in Ge_xSi_1−x/Si(110) heterostructures. It is shown that above a critical composition, the critical thickness for edge a/6〈112〉 Shockley partial dislocations is less than that for 60° a/2〈110〉 total dislocations. The net (excess) stress is greater on the edge a/6〈112〉 dislocations for epilayer thicknesses, h<h_x, but greater on the 60° a/2〈110〉 dislocations for h≳h_x. The sensitive calculated dependence of h_x upon the stacking fault energy per unit area γ allows an experimental determination of γ=65±10 mJ m⁻² for x∼0.3 in Ge_xSi_1−x.