Molecular-dynamics simulations of low-energy Cu-6 cluster deposition on Cu(001) and Au(001) surfaces

In this paper, the deposition of Cu-6 cluster with a stable octahedral stru cture on Cu(001) and Au(001) surfaces in tenth of picoseconds is investigat ed by molecular-dynamics simulations, in which the Finnis-Sinclain potentia l is used to describe the interactions between copper and gold atoms. The i ncident energy of the cluster ranges from 0 to 30 eV per atom. By taking "s napshots" and analyzing the energy partition during the deposition process, it is found that the cluster atoms could rearrange themselves from the ori ginal octahedral structure into a fee structure and eventually form an epit axial layer. The penetration depths of the cluster atoms increase with the impact energy. The substrate suffers damages when the impact energy is incr eased over a threshold value. Compared with copper surface I the energy thr eshold for gold surface is a little higher than that for copper surface. Th e simulations also show that the reconstruction. of cluster atoms on surfac e is completed in a very short time (a few picoseconds), and during which t he collision cascade plays an important role in the cluster reconstruction. Our simulation supports the related experimental results that the low ener gy cluster beam deposition (LECBD) is favourable for the formation of the n anostructured thin films, which can be controlled by varying the incident e nergy of clusters.