Atomic ordering and the surface morphology of thin films

The formation of ordered phases and associated surface instabilities during the growth of alloy films is studied using a nonequilibrium model. It is shown that considerations of the epitaxial thermodynamic energy as well as dynamical processes at the surface lead to a coupling between the order parameter, the composition and the surface morphology. It is demonstrated that the stability of the growing layer against atomic ordering depends on the growth rate and that even when the surface-selected ordered phase is thermodynamically unstable, the system can spontaneously order.