The bombarding-angle dependence of sputtering yields under various surface conditions

Using the ACAT code, the bombarding angle-dependence of sputtering yields has been investigated under various surface conditions. Three different models of rough surfaces are employed: (1) the rough surface with randomly distributed vacancies at the topmost layer, (2) the rectangluar-step surface, and (3) the oblique-step surface with the same inclined angle as the angle of incidence. It is found that the ion-bombardment-induced surface roughness greatly influences the bombarding-angle dependences of both the sputtering yield and the particle reflection coefficient. Due to the surface roughness the surface scattering is reduced and this effect results in the shift of the bombarding angle for the maximum sputtering yield to a higher angle of incidence.