Control of misfit dislocations in strain-relaxed SiGe buffer layers on SOI substrates

A thin strain-relaxed SiGe buffer layer with pure-edge dislocations has been grown on a silicon-on-insulator (SOI) substrate by using low-temperature epitaxy of Ge and subsequent high-temperature annealing. The dislocation morphology and crystalline mosaicity of the strain-relaxed SiGe layers has been measured, and the influence of the thickness of the SiGe and SOI layers on these features has been investigated. Behavior of the dislocations introduced from the interface between the SiGe and the buried oxide layers during high-temperature annealing shows a high dependence on the thickness of the SOI layer. This SOI thickness dependence can be explained by considering the effects of the image force exerted on the dislocations. A higher temperature anneal and a thinner SOI layer are both found to reduce the crystalline mosaicity.