Resonance photoemission studies of (111) oriented CeO2 thin film grown on Si (100) substrate by pulsed laser deposition.

The electronic structure of CeO₂ thin film grown by pulsed laser deposition on Si (100) substrate has been investigated using resonance photoemission spectroscopy (RPES). X-ray photoemission study on the film suggests that Ce has 3+ and 4+ valence states. Valence band spectra of the film show a feature at 2.1 eV of binding energy and a broad band at higher binding energy due to O 2p derived state. RPES measurements performed in the Ce 4d→4f photoabsorption region show maximum intensity for 2.1 eV feature at photon energy of 122 eV confirming it to be due to Ce³⁺ (4f¹) state. RPES measurements also show maximum intensity for binding energy position of 4.4 eV in the broad band at photon energy of 125 eV, suggesting it to be due to Ce⁴⁺ (4f⁰) state. Constant initial state (CIS) versus photon energy plots also confirm these findings and suggest that the broad band is admixture of O 2p and Ce 4f and 5d derived states. [ABSTRACT FROM AUTHOR]