X-ray reflectivity studies of highly crystalline CeO2 films on (1 1 0 2) Al2O3

We observed highly single crystalline epitaxial growth of CeO2 films on a (1 1 0 2) (r-cut) Al2O3 (sapphire) using X-ray reflectivity and diffraction. The X-ray reflectivity data indicate a presence of a thin interfacial layer between CeO2 film and r-cut sapphire with a lower electron density than that of CeO2. Above the interfacial layer, the mechanism of film growth deduced from the reflectivity and diffraction data indicates two-dimensional layer growth. The surface roughness of 394 Å thick film is 5 Å, and the film shows nearly strain-free growth.