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Minimum energy paths for dislocation nucleation in strained epitaxial layers

O. Trushin, E. Granato, S. C. Ying, P. Salo, T. Ala-Nissila

cond-mat.mtrl-sciarXiv:cond-mat/0205620

Abstract

We study numerically the minimum energy path and energy barriers for dislocation nucleation in a two-dimensional atomistic model of strained epitaxial layers on a substrate with lattice misfit. Stress relaxation processes from coherent to incoherent states for different transition paths are determined using saddle point search based on a combination of repulsive potential minimization and the Nudged Elastic Band method. The minimum energy barrier leading to a final state with a single misfit dislocation nucleation is determined. A strong tensile-compressive asymmetry is observed. This asymmetry can be understood in terms of the qualitatively different transition paths for the tensile and compressive strains.

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