(Digital Presentation) Strain Engineering of Heteroepitaxial SiGe/Ge on Si with Various Crystal Orientations

Strained SiGe layers with high Ge concentrations are grown on the Ge and Ge-on-Si substrates with various crystal orientations, and structural properties are studied. Particularly, initial stages of defect formation and related surface morphology are investigated. It is found that cracks are generated in the tensile-strained layer and surface ridge roughness is formed around the cracks although the total relaxation ratio of the SiGe layer is almost 0 %. Due to annealing the tensile strain is partially relaxed by creating additional trench-like roughness with the initially formed ridge roughness left unchanged. This comparative investigation of strain relieving defect formation provides quite useful information toward applications to strained SiGe-based optoelectronic and spintronic devices with enhanced performances.