Elastic strain relaxation in free-standing SiGe/Si structures

Abstract

We have investigated elastic strain relaxation, i.e., strain relaxation without the introduction of dislocations or other defects, in free-standing SiGe/Si structures. We fabricated free-standing Si layers supported at a single point by an SiO2 pedestal and subsequently grew an epitaxial SiGe layer. The measured strain relaxation of the SiGe layer agrees well with that calculated using a force-balance model for strain sharing between the SiGe and strained Si layers. We report strained Si layers with biaxial tensile strain equal to 0.007 and 0.012.