Roughness and ordering of growing films

In many deposition processes particles are highly mobile in an active layer at the surface, but are relatively inert once incorporated in the bulk. Inhomogeneities in the deposition process then lead to formation of rough surfaces, whose height fluctuations can be probed directly by scanning microscopy, or indirectly by scattering. I shall first briefly review analytical or numerical treatments of simple homoepitaxial growth models which suggest that the height fluctuations have a self-similar character, well described by a dynamic scaling form. I then study models of heteroepitaxial growth in which different atoms are allowed to interact, equilibrate, and order (e.g. phase separate) on the surface, but are frozen in the bulk. Order parameter correlations in the resulting bulk material are highly anisotropic, reflecting its growth history. In a flat (layer by layer) growth mode, correlations perpendicular to the growth direction are similar to a two-dimensional system in equilibrium, while parallel correlations reflect the dynamics of such a system. When the growing film is rough, various couplings between height and order parameter fluctuations are possible. Such couplings modify the dynamic scaling properties of surface roughness, and may also change the critical behavior of the order parameter. Even the deterministic growth of the surface profile can result in interesting textures for the order parameter.