Fragmentation, coalescence and deposition of silicon clusters studied by molecular dynamics

Cluster deposition is a technique recently developed for the production of films of a nanometric thickness. The technique consists on driving a beam of clusters onto a substrate with an energy sufficient to obtain their fragmentation and the adhesion of the fragments to the substrate. Therefore the main mechanisms involved by this technique are (i) cluster fragmentation, (ii) cluster-substrate adhesion and (iii) coalescence of the deposited fragments. \ The focus of this study is on these three mechanisms. To illustrate their peculiar features, three structures have been selected. Two of these structures, that is a cluster and a cluster dimer, are free standing. The third one represents a cluster deposited onto a substrate. The temperature response of the two free standing structures illustrates the effects of the cluster geometry and shape on the response to an external energy input. The comparison of these responses with the behavior occurring during deposition illustrates the main properties of cluster-substrate interactions.