Preparation and microstructural study of CeO2 thin films

Epitaxial and textured ceria films were prepared by conventional electron-beam evaporation on (001) LaAlO3, (1 (1) over bar 02) R-cut sapphire, (001) Au, and (001) Pd substrates using ceramic and metallic sources. Deposition temperature and deposition rate were varied to determine their effects on the formation of the CeO2 films. It was also found that the epitaxial formation of CeO2 films varied with different substrates and evaporation sources. Ceria films grew epitaxially on sapphire with a deposition rate less than 0.5 Angstrom/s in the temperature range of 650-750 degrees C using either ceramic or metallic source. The epitaxial growth of CeO2 on LaAlO3 occurred at deposition rates as high as 1.0 Angstrom/s at a deposition temperature as low as 600 degrees C using a metallic source, while on the (001) Au substrate, only a textured structure was observed between 580 and 700 degrees C and at deposition rates from 0.3 to 1.0 Angstrom/s. On a (001) Pd substrate, the deposited CeO2 films showed a different microstructure corresponding to ceramic and metallic sources at deposition rates of 0.2-0.5 Angstrom/s and from 700 to 750 degrees C. The epitaxial ceria films were achieved using a ceramic source, while the polycrystalline ceria films of multiple twinning were obtained using the metallic source. The epitaxial growth temperature of CeO2 on these substrates was empirically found to be around 700 degrees C (i.e., 0.35 T-m). (C) 1997 American Vacuum Society.