Structure and chemical states of highly eptiaxial CeO2(001) films grown on SrTiO3 substrate by laser molecular beam epitaxy

Highly epitaxial and pure (001)-oriented CeO2 films were grown on SrTiO3(001) substrates by laser molecular beam epitaxy method without any gas ambient. Layer-by-layer epitaxial growth mode of CeO2 was confirmed by in situ reflection high-energy electron diffraction (RHEED) observations. High-resolution X-ray diffraction (HRXRD) and high-resolution transmission electron microscopy (HRTEM) results indicated the STO(100)//CeO2(100), STO[100]//CeO2[110] epitaxial relationship for out-of-plane and in-plane, respectively. The formation mechanism of the epitaxial film was also discussed in the light of a theoretical model. Chemical states of the LMBE ceria films were evaluated and evidences for the existence of Ce3+ and oxygen vacancies were presented.