A necessary condition for the appearance of damage-induced surface-topography during particle bombardment

Abstract

A first approach to the establishment of an “order-of-magnitude” criterion for the initiation of damage-induced surface topography on clean and well-polished metal single crystals is proposed. It is based on a model proposing a mechanism of preferential erosion of parts from the sample surface due to a local increase of sputtering yield above “extensive defects”. These “extensive defects”, resulting of the migration of the point-defects, created during the collision-cascade started by the incoming ions, can indeed influence the sputtering yield if they are located close under the surface, i.e. when the surface has regressed, due to sputtering, to the level where these “extensive defects” have been formed. The condition implies that the formation of “extensive defects” must have taken place before the surface reaches them. The condition is written in terms of the irradiation parameters and quantities characteristic for the migration of point-defects due to the presence of a potential gradient related to the “extensive defects” under formation.