Misfit dislocation dipoles in Si/SiGe/Si heterostructures on SOI

Transmission electron microscopy (TEM) and synchrotron radiation double-crystal topography (SRDT) have been employed to investigate Si/SiGe/Si heterostructures grown by ultra-high vacuum chemical vapor deposition (UHVCVD) on bonded Si-on-insulator (SOI) wafers. A configuration of misfit dislocation dipoles is observed by high-resolution transmission electron microscopy (HRTEM). The dislocation dipoles are mostly of 60° type and three types of 60° dislocation dipoles, extrinsic, intrinsic, and null, are presented. Dark-field images (DFIs) indicate no lateral compositional modulations but strain distribution appearing in the SiGe layer, which is supported by the SRDT topograph. We suggest that the lateral strain modulation in the SiGe layer and subsequent annealing play an important role in the introduction of the dislocation dipoles.