Molecular dynamics simulations study of nano particle migration by cluster impact

Abstract

Molecular dynamics (MD) simulations are performed in order to investigate the radiation effects of a huge and slow gas cluster for the surface cleaning process. When a large argon cluster with the size ranging from 20, 000 to 300, 000 is accelerated with a total of 30. keV, each constituent atom carries very low energy ranging from 1.5. eV/atom to 0.1. eV/atom. In many cases, the cluster does not penetrate the solid target surface but is deflected in a lateral direction. This collisional process results in a high density particle flow spreading along the surface plane due to cohesion of the cluster, which suggests the capability to modify the irregular surface structure, without damage in the target. The MD simulations demonstrate that such a huge cluster sweeps a nano particle (NP, 3. nm in radius) attached on a planar silicon target's surface. From the investigation of various conditions of cluster impact, it is found that the migration distance is correlated with the kinetic energy applied on the NP by the impact of cluster atoms. Additionally, the MD results suggest the existence of optimized parameters for the maximum migration distance for the offset distance between the cluster and the NP, and the cluster size for constant total energy (equivalent to energy per atom or kinetic energy density). The optimized offset distance was estimated as the summation of radii of the incident cluster and the NP. The optimized energy per atom was suggested around 0.6. eV/atom, where the cluster efficiently spreads in lateral direction keeping higher kinetic energy density of particle flow.