Growth of ultra-thin cerium oxide layers on Cu(1 1 1)

The reactive vacuum deposition of CeO2 on Cu(1 1 1) surface in oxygen atmosphere provides high quality epitaxial ceria overlayers. We report the growth characteristics of Ce oxide, the structures, and the temperature stability of the oxide phases as investigated by low-energy electron diffraction (LEED) and X-ray photoelectron spectroscopy. We find that Ce oxide on the Cu(1 1 1) grows initially in the form of islands giving sharp hexagonal LEED pattern of the CeO2(1 1 1) structure corresponding to the (1.5 × 1.5) structure. The CeO2–Cu(1 1 1) films exhibited mixed valence states and temperature dependent CeO2–Ce2O3 transition above 900 K due to the vacuum annealing. The transition progressed more rapidly at the surface, probably by formation of oxygen vacancies.