The effects of substrate size and temperature on the deposition of Cu clusters on a Si substrate

Abstract

The deposition of a Cu13 cluster on a Si (001) surface was studied by molecular dynamics simulations. Embedded atom method, Stillinger-Weber, and Lennar-Jones potentials were used to describe the interaction between cluster atoms, substrate atoms, and the cluster-substrate interaction. Quantitative characteristic parameters, such as kinetic energy of the cluster and the substrate, the degree of epitaxy, and the mean height of mass center of the cluster, were calculated to study the effect of substrate size and substrate temperature on cluster deposition. The substrate temperature was found to affect the degree of epitaxy at different substrate sizes. When the size ratio of the substrate and cluster is relatively small or large, the epitaxial degree was higher at 800 K than at 300 K. If the size of the substrate matches that of the cluster, the substrate temperature appeared to have minimum effect. For a given temperature, the substrate size was found to have no obvious effect on the degree of epitaxy or the mean height of mass center of the cluster. This observation indicated that simulations using even a small system can still give reliable results and qualitative description of the deposition phenomena. We also found that the cluster atoms prefer to diffuse along the [110] direction on the Si (001) surface.