GROWTH AND PERCOLATION OF THIN-FILMS - A MODEL INCORPORATING DEPOSITION, DIFFUSION AND AGGREGATION

We propose a model for describing diffusion-controlled aggregation of parti cles that are continually deposited on a surface. The model, which incorporates deposition, diffusion and aggregation, is motivated by recent thin film deposition experiments. We find, that the diffusion and aggregation of randomly deposited particles ''builds'' a wide variety of fractal structures, all characterized by a common length scale L(1). This length L(1) scales as the ratio of the diffusion constant over the particle flux to the power 1/4. We compare our results with several recent experiments on two-dimensional nanostructures formed by diffusion-controlled aggregation on surfaces.