Binary collision approximation simulations of ion solid interaction without the concept of surface binding energies

Abstract

The sputtering yield of atoms removed from a solid upon ion irradiation can be calculated using Monte Carlo simulations based on the binary collision approximation. These simulations rely on the assumption of a planar surface potential barrier similar to the work-function for electron emission. Although this model yields good agreement with experimental data, the surface binding energy often has to be arbitrarily adjusted. We propose the bulk binding energy model to calculate sputter yields using sublimation enthalpies and a spherically symmetric potential barrier at the position where the sputtered atoms are generated in the bulk. A planar potential barrier at the surface no longer exists. We also consider the energy density deposited in nuclear collisions, which may lead to a lower sublimation enthalpy compared to standard room temperature conditions. The new bulk binding energy model is able to quantitatively explain many experimental sputtering data.