Generation of misfit dislocations and stacking faults in supercritical thickness strained-Si∕SiGe heterostructures

Abstract
Defects in the supercritical thickness strained-Si layer grown on a fully relaxed SiGe buffer layer were investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The AFM observation of chemically etched surfaces showed that etch pits having a crosshatch pattern due to misfit dislocations decrease and segments and deep valley profiles increase with an increase in the strain energy of the Si. We found that the segment corresponds to an extended dislocation, of which a 30° partial is in the strained-Si layer and a 90° partial is in the SiGe layer, and the deep valley corresponds to a stacking fault found by a high-resolution TEM observation. A model of the generation of the stacking fault related to development of the misfit dislocation is also discussed here.