We propose a model for describing diffusion-controlled aggregation of particles 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 L1. This length LI scales as the ratio of the diffusion constant over the particle flux to the power l/4. We compare our msults with several recent experiments on two-dimensional nanostructures formed by diffusion-controlled aggregation on surfaces.

We propose a model that describes the diffusion-controlled aggregation exhibited by particles as they deposited on a surface.The model, which incorporates deposition, particle and cluster diffusion, and aggregation, is inspired by recent thin-film-deposition experiments. We find that as randomly deposited particles diffuse and aggregate they configure themselves into a wide variety of fractal structures characterized by a length scale L1. We introduce an exponent y that tunes the way the diffusion coefficient changes with cluster size: if the values of y are very large, only single particles can move, if they are smaller, all clusters can move. The introduction of cluster diffusion dramatically affects the dynamics of film growth. We compare our results with those of several recent experiments on two-dimensional nanostructures formed by diffusion-controlled aggregation on surfaces, and we propose several experimental tests of the model. We also investigate the spanning properties of this model and find another characteristic length scale L2 (L>>L1) above which the system behaves as a bond percolation network of the fractal structures each of length scale L1. Below L2, the system shows similarities with diffusion-limited aggregation. we find that L1 scales as the ratio of the diffusion constant over the particle flux to the power 1/4, whereas L2 scales with another exponent close to 0.9.

We propose a model for describing diffusion-controlled aggregation of particles that are continually depostied on a surface. The model incorporates deposition, diffusion, and aggregation. We find that the diffusion and aggregation of randomly deposited particles