Thermodynamics of thin film epitaxy

The mechanics of thin film epitaxy is developed using an equilibrium thermodynamics formalism and linear elasticity. A virtual variation approach is employed that leads to a direct identification of the important volume and surface thermodynamic parameters characterizing mechanical equilibrium. In particular, the equilibrium volume stress state of an epitaxial film as a function of the film thickness, surface free energies, and surface stresses is obtained. It is shown how this formalism can be used to determine the critical thickness for epitaxy.