Diffusion controlled growth of metallic nanoclusters at selected surface sites

Abstract
We have investigated the growth of three-dimensional Ag particles at atomic steps on the surface of highly oriented pyrolytic graphite using a scanning electron microscope. By controlling the growth parameters the cluster growth was confined to the steps avoiding terrace nucleation. In this way quasi-one-dimensional chains of Ag nanoclusters of approximately 10 nm diam were produced. The results suggest the viability of an important new route to the creation of controlled nanoscale structures. A comprehensive surface study indicates that cluster mobility and coalescence play an important role in the growth mechanism on the steps. Evidence was also found that the graphite surface has several different types of surface steps. A quantitative analysis of the cluster distribution on the steps was performed, to investigate the nucleation and growth processes at temperatures from 50 to 205 °C.