(Invited) Anisotropic Strain Introduction into Si/Ge Hetero Structures

We show that anisotropic strain can be induced into Si/Ge hetero structures by growing them on selectively ion-implanted substrates. It is found that strain relaxation of SiGe buffer layers takes place through generation of misfit dislocations along one direction, perpendicular to the selectively ion-implanted stripe patterns. As a result, the SiGe buffer layers accommodate anisotropic (uniaxial) strain states, which are highly stable and controllable since the relaxation is based on the plastic deformation by the dislocations. On the strain controlled SiGe buffers, uniaxially strained Si/Ge channels can be grown and are highly applicable to high-mobility complementary metal oxide semiconductor (CMOS) channels.