Epitaxial Growth of CeO2 Films on Si(111) by Sputtering

CeO2 films were epitaxially grown on Si(111) substrates by reactive sputtering following the single-crystal CeO2 seed layer formation by oxygen-reactive solid-phase epitaxy. Formation of metallic Ce layers and oxidation of the layers prior to reactive sputtering was found to be the key process for epitaxial growth of CeO2 on Si substrates. An Auger electron spectroscopy depth profiling analysis showed that the Ce–Si interlayer was formed after the Ce metal deposition. Reflection high-energy electron diffraction and transmission electron microscopy proved that epitaxial CeO2 films were grown by reactive sputtering on the seed layers formed by oxidation of Ce metal layers with thickness of 5 to 10 nm. Crystalline quality of the films depended on the sputtering conditions, especially on total sputtering pressure and oxygen concentration. The optimization of the conditions for seed layer formation by oxygen-reactive solid-phase epitaxy and reactive sputtering was an important factor for improving the crystalline quality of epitaxially grown CeO2 film.