Dislocations and stress relaxation in heteroepitaxial films

A few important elastic properties of dislocations that are relevant for a study of stress relaxation in thin layers are recalled at an elementary level. The elastic interactions of a dislocation with a free surface and an interface are then briefly discussed. The concept of critical thickness for the relaxation of misfit strains in heteroepitaxial films is introduced in a simplified manner. This notion, which makes use of an equilibrium arguments is critically discussed in the last part with emphasis on several kinetic effects and energy barriers, particularly those associated with the mechanisms of dislocation generation and mobility.