Calculations were made of the surface energy change due to step formation, as caused by misfit dislocation nucleation in thin-film semiconductor heterostructures. It was found that the surface energy change was negative for a compressive misfit stress in the hetero-epitaxial film, whereas it was positive for a tensile misfit stress. This conclusion contrasted with the classical model, in which the step formation energy was always positive and was independent of the sign of the misfit. The calculated energy change was qualitatively explained by counting the number of dangling bonds on the surface. By using atomistic simulations, calculations were made of the critical thickness of dislocation nucleation; taking into account the surface energy change. It was shown that it varied from 4nm for Ge films on Si(001) substrates, to 6nm for Si films on Ge(001) substrates having the same misfit.

Negative Surface Energy Change Associated with Step Formation caused by Misfit Dislocation Nucleation in Semiconductor Heterostructures. M.Ichimura, J.Narayan: Philosophical Magazine A, 1995, 72[2], 297-304