Influence of misfit and bonding on the mode of growth in epitaxy

Abstract
The relative stability of monolayer and double-layer epitaxial islands consisting of equal numbers of atoms is studied within the framework of the Frankvan der Merwe model as a function of island size, misfit, stiffness of the layer, and strength of film-substrate interaction. An exact solution of the governing equations has been obtained after linearization. The validity regimes of the results have been established. The main conclusion is that both registry strain energy and misfit energy considerably enhance the tendency to three-dimensional growth when the misfit becomes significant. At small misfit surface free energies are dominant. The predictions are compared with empirical data. Although some uncertainties still exist, the agreement with experiment is encouraging.