Investigation of Si/SiGe/Si on Si-on-insulator by high resolution electron microscopy and synchrotron radiation double-crystal topography

High resolution transmission electron microscopy (HRTEM) in combination with synchrotron radiation double-crystal topography (SRDT) has been employed to investigate Si/SiGe/Si on silicon-on-insulator (SOI) subjected to in situ low-temperature annealing. Three types of dislocation dipoles have been found in HRTEM cross-sectional images of this multilayer structure, for the first time. The formation of dislocation dipoles is due to the internal misfit stress. The crosshatched and bumpy contrasts have been observed in SRDT topographs. Comprehensive analyses indicate that major strain relaxation happens in SiGe layer and in the vicinity of its lower interface. The strain relaxation of Si/SiGe/Si on SOI subjected to in situ low-temperature annealing does not depend on the mechanism of compliancy but on the introduction of single dislocations, dislocation dipoles and locally elastic strain.