Formation of misfit dislocations in nanoscale Ni–Cu bilayer films

Abstract

We investigated the mechanism of interface dislocation formation in a 5.0 nm Ni film epitaxially deposited on 100 nm of Cu(001). Threading dislocations that pre-exist in the Cu substrate extend into the coherent Ni overlayer during growth and propagate in the [110] and directions along the interface. These dislocations are perfect glide dislocations with mixed character and lying on the Ni{111} planes, and were by far the most numerous in the microstructure. Lomer edge dislocations lying on the Ni–Cu(001) interface were also detected, constituting approximately 5% of the total interface dislocation content. Closely spaced adjacent pairs of perfect glide dislocations having the same Burgers vector were commonly observed at the interface. This dislocation configuration, together with several others that were observed, is explained in terms of the ability of favourably oriented dislocations to cross-slip.