INFLUENCE OF CLUSTER DIFFUSION ON THE COARSENING OF XE FILMS ON PT(111)

The diffusion of clusters of atoms or vacancies on single-crystal surf aces can have an important; impact on the evolution of films. We have investigated the role of cluster diffusion in the coarsening of cluste rs with a detailed lattice gas model of commensurate Xe films on Pt(11 1). Both atomic and vacancy clusters can diffuse in this system. We sh ow that, while cluster diffusion and coalescence are the dominant coar sening mechanisms for vacancy clusters, the coarsening of atomic clust ers is dominated by Ostwald ripening. We have also used our lattice ga s model to test several microscopic assumptions that are made in macro scopic theories of cluster coarsening. (C) 1997 American Vacuum Societ y.