Understanding the growth of nanocluster films

What are the mechanisms leading to the growth of nanostructures when preformed clusters are deposited on a surface? We present here the main physical processes which control the density and shape of the islands. As these processes span a large time scale, their understanding demands a variety of simulation approaches. We will focus here on an important issue for future technological applications of cluster deposition: the relation between the size of the incident clusters and the size of the islands obtained on the substrate. Kinetic Monte Carlo simulations of two- and three-dimensional islands show that the shape relaxation of the nanocrystallites cannot be explained by the usual theories of equilibration. Indeed, below the roughening temperature, the relaxation is much slower, kinetics being governed by the nucleation of a critical germ on a facet. This dramatically changes the size dependence of the equilibration time. (C) 2002 Elsevier Science B.V. All rights reserved.