Numerical studies were made of the energetics and atomic mechanisms of misfit dislocation nucleation and stress relaxation in a 2-dimensional atomistic model for strained epitaxial layers on a substrate, with lattice misfit. Relaxation processes, ranging from coherent to incoherent states for different transition paths were studied by using interatomic potentials of Lennard-Jones type and a saddle-point and transition-path search method. The model was based upon a combination of a repulsive potential minimization

and the a nudged elastic band method. The minimum-energy path and the corresponding activation barrier were obtained, for various misfits and interatomic potentials, for a final state with a single misfit dislocation. It was found that the energy barrier decreased sharply with misfit. A marked tensile-compressive asymmetry was observed. This was seen as being a manifestation of the asymmetry between repulsive and attractive branches of the pair potential. It was found to depend sensitively upon the form of the potential.

Energetics and Atomic Mechanisms of Dislocation Nucleation in Strained Epitaxial Layers. O.Trushin, E.Granato, S.C.Ying, P.Salo, T.Ala-Nissila: Physical Review B, 2003, 68[15], 155413 (8pp)