Influence of the surface relief on the energy dependence of sputtering coefficient

The influence of the surface relief on the energy dependence of the sputtering coefficient S of a copper target under bombardment by argon ions with the energies E0 = 0.3-100 keV has been investigated by the method of statistical trials. The calculations predict a strong effect of the inclination angle of the walls of pointed asperities (ridges, pyramids and cones) on the shape of the energy dependence of S. The sputtering coefficient reaches its maximum value S0m at the energy E0m, which increases from 6 to 70 keV with changing the inclination angle of the facets Ψb from 0 to 85° The non-monotonous dependence of S on Ψb at the normal incidence of ions is confirmed. The angle Ψbm corresponding to Sbm for the dependence S(Ψb) varies from ∼5 to 65° in the investigated range of ion energies. The dependence S(E0) is calculated on the assumption that the relief with the inclination angles of the microasperities is developed under ion bombardment which have the same energy dependence as the angle of maximum sputtering on the experimental dependences of S on the angle of the ion incidence. The calculation gives the value of E0m at 30 keV and provides a good agreement with the experimental data.