Molecular dynamics simulation of gas clusters impact on solid targets

The interaction of a cluster of Arn (n=87-300) on a gold and silicon substrate was simulated by use of ordinary and Langevin Molecular Dynamics. The cluster was prepared by cutting out of a spherical f.c.c. block of Dynamics. The Buckingham potential was used for an interaction between the argon atoms. The excitation of the argon atoms due to high temperature and/or high pressure inside the cluster have been taken into account by use of a Monte-Carlo procedure. The N-body potential proposed by Rosato for gold and Axilrod-Teller 3-body potential for silicon was used, which describes well equilibrium properties of bulk material. The substrate was modeled using a b.c.c. lattice (for gold) and diamond (for silicon) of about 30000 atoms. These atoms were separated into three regions, depending on how near they are the impact zone. The atoms of central impact zone are being described by NM. The next zone consists of several semi-spherical layers of a thermal bath, for which the LMD was used. All the other atoms represent the movable (in radial direction) or rigid framework. The kinetic energy of the clusters is varied from 10 to 100 eV/atom. It has been shown that the impact of energetic Ar cluster with the kinetic energy of 100 eV/atom on a gold target sputters not only single atoms but also small gold clusters in the 10 atoms range. Lateral sputtering of gold target material has been predicted. Preliminary results for argon clusters implantation into the silicon (111) shows that this process seems to be quite small due to the very weak bond energy between argon and silicon atoms