Growth of CeO 2 Films on Sapphire and MgO by rf Magnetron Sputtering

pitaxial CeO 2 films on (1102) sapphire and (100) MgO were grown by rf magnetron sputtering. Substrate temperature, total pressure, and oxygen‐to‐argon mole ratio were varied to explore the optimal deposition condition. The X‐ray diffraction spectra indicate that the degree of crystallinity of the deposited CeO 2 films depends on the oxygen‐ to‐argon mole ratio and the substrate temperature. Atomic force microscopy images of the films on sapphire and MgO showed that substrate temperature and total pressure affect surface roughness. The best film surface is smooth with a 0.89 nm root‐mean‐square roughness. The quality of the films on MgO showed a strong dependence on substrate pretreatments. Epitaxial CeO 2 films could be grown on pre‐ annealed or pre‐etched MgO if substrate temperatures reached higher than 790 deg; C. Additionally, the effect of ion bombardment at low total pressures on the crystallinity of the films was examined by growing the films outside the plasma region. Experimental results indicate that the ion bombardment does not prevent the films from preferred orientation.