Using transmission electron microscopy, the dissociation of 60° misfit dislocations at the interface of SiGe/Si multi-layers was observed; extending into the substrate to distances of 5.0 to 7.5nm. Analysis, using elasticity theory, showed that this dissociation was the equilibrium configuration for individual 60° misfit dislocations, as it was for 60° mixed dislocations in bulk Si. The compressively strained multilayer film served mainly to position the partial dislocations and stacking fault with respect to the free surface. Both undissociated 60° and Lomer edge dislocations were observed after annealing, and it was concluded that these resulted from dislocation climb in the interface. Because the dislocations moved off their slip plane during climb, they could not remain dissociated. Significant climb and Lomer-dislocation formation was observed for these low misfit layers at above 850C and for samples with a high initial dislocation density; such as those found in thicker as-grown samples. The dislocation configuration which formed during annealing was distinct from that reported to form during the growth of higher-mismatch films. The Lomer dislocations tended to be segmented, with the segments being connected by perfect 60° dislocations

Misfit Dislocation Dissociation and Lomer Formation in Low Mismatch SiGe/Si Heterostructures. A.F.Marshall, D.B.Aubertine, W.D.Nix, P.C.McIntyre: Journal of Materials Research, 2005, 20[2], 447-55