Experimental observation of nucleation of misfit dislocations induced by the stress field of primary dislocations

Abstract

Lomer-type edge dislocations (L-dislocations) detected in strained films Ge-on-Si, GaAs-on-Si, etc., are formed from two 60° dislocations sliding along intersecting {111} planes inclined with respect to the (001) substrate.Kvam et al. [J. Mater. Res.5(1990) 1900] proposed a mechanism of induced generation of a secondary 60° dislocation as one of the variants of L-dislocation formation. The present paper describes the analysis of the dislocation structure arising at the initial stage of growth of strained Ge films on Si substrates with the surface tilted from the [001] orientation. Nucleation of the secondary misfit dislocation is found to be induced by the front of the expanding primary dislocation, i.e., by its segment reaching the film surface.