The minimum-energy path and energy barriers for dislocation nucleation in a 2-dimensional atomistic model of a strained epitaxial layer on a substrate, with lattice misfit, were studied numerically. Stress relaxation processes ranging from coherent to incoherent states for various transition paths were determined by using a saddle-point search that was based upon repulsive-potential minimization and nudged elastic band methods. The minimum-energy barrier leading to a final state with a single misfit dislocation nucleation was determined. A strong tensile-compressive asymmetry was observed. This asymmetry could be understood in terms of the qualitatively different transition paths for tensile and compressive strains.

Minimum Energy Paths for Dislocation Nucleation in Strained Epitaxial Layers. O.Trushin, E.Granato, S.C.Ying, P.Salo, T.Ala-Nissila: Physical Review B, 2002, 65[24], 241408 (4pp)