The effect of target aging on the structure formation of zinc oxide during reactive sputtering

A comparative study of reactively sputtered zinc oxide films deposited using (a) a new metallic Zn target and (b) an old one with a pronounced erosion trace is presented. Depending on the shape of the target surface there, are pronounced differences in the film structure. These findings are attributed to a correlation between the target surface profile and ion bombardment of the growing film. Main candidates for the differences in film structure are negatively charged oxygen ions generated at the oxidized target surface.