Cluster species and cluster size dependence of damage formation by cluster ion impact

Abstract

Molecular dynamics simulations of Ne, Ar and Xe clusters with various sizes impacting on Si surfaces were performed in order to study damage formation processes. When cluster size ranged from several tens to several thousands and accelerated energy is 20 keV in total, each cluster impact caused surface damage in the shape of a crater. A larger number of displacements was found with the Xe cluster than Ne and Ar clusters of the same cluster size because the Xe cluster had a larger mass and momentum. However, when cluster size exceeded several thousands, different surface damage structures were formed depending on the cluster species. At a cluster size of 10,000, for example, a crater-like trace was still formed with a Ne cluster impact. However, both the depth of the crater and the number of displacements decreased as the atomic number of the cluster atom increased, which meant that the atomic and energy density irradiated on the surface is a dominant parameter in causing surface damage. These results indicate that the damage formation by cluster impact can be controlled by changing the cluster species as well as the incident energy and cluster size.