Few collisions approach for threshold sputtering

Abstract

Based on a few collision model, analytic relations for the threshold sputtering energy at not too oblique ion incidence are derived. It is found that for this minimum energy-loss process, the scattering angle is equal for each collision. The sputtering threshold energy at grazing ion incidence is numerically calculated taking into account the shadowing effect and the effective periodicity of neighbouring atoms at the surface. The threshold energy for heavy-ion sputtering is a decreasing function of the angle of incidence until about 60°. The threshold energy of light-ion sputtering is nearly constant until about 85°. Calculated threshold energies for normal incidence are in good agreement with experimental values.