Computing the Equilibrium Configuration of Epitaxially Strained Crystalline Films

We study a model for shape instabilities of heteroepitaxial crystalline films. Lattice misfits between the substrate and the film induce elastic stresses in the film, which adjusts the shape of its free surface to reduce its total energy, sum of an elastic and a surface energy. We give a precise framework that guarantees the existence of solutions to this variational problem. We show that equilibrium states can be approximated using a two-phase model for representing the surface energy. Numerical results, obtained via this approximation, are presented.