Microstructural change in SiGe/Si hetero interface of SiGe on insulator (SGOI) wafer with annealing was investigated by transmission electron microscopy. Misfit dislocations were observed in the specimen annealed at 1203 K. With further annealing above 1373 K, the straight shape of the misfit dislocations is change to the randomly curved and tangled with locking of the dislocation generated by the reaction of the two crossing misfit dislocations. Change in the morphology of the dislocation was also discussed from the crystallographic viewpoint. (c) 2008 Elsevier B.V. All rights reserved.