Tensely strained silicon on SiGe produced by strain transfer

An approach for the controlled formation of thin strained silicon layers based on strain transfer in an epitaxial Si ∕ SiGe ∕ Si ( 100 ) heterostructure during the relaxation of the SiGe layer is established. He + ion implantation and annealing is employed to initiate the relaxation process. The strain transfer between the two epilayers is explained as an inverse strain relaxation which we modeled in terms of the propagation of the dislocations through the layers. Effcient strain buildup in the Si top layer strongly depends on the Si top layer thickness and on the relaxation degree of the SiGe buffer. 100% strain transfer was observed up to a critical thickness of the strained silicon layer of 8 nm for a 150 nm relaxed Si 0.74 Ge 0.26 buffer.