We have prepared c-axis controlled Fe2O3 thin films on Al2O3 substrates by RF magnetron sputtering and studied their electronic structure by soft-X-ray spectroscopy. The lattice constant of c-axis increases with increasing film thickness due to the relaxation of lattice mismatch between Fe2O3 and Al2O3 and formation of oxygen vacancies. The electrical conductivity is higher in thicker thin film. The valence band consists of t2gand eg-subbband of Fe 3d state hybridized with O 2p state. The band gaps of >25 and >95nm thicknesses of Fe2O3 thin film are >1.8 and 1.4 eV, respectively, which correspond to the activation energy of electron conductivity. The above results indicate that the band gap and the conductivity of Fe2O3 thin film directly affect the change of the lattice constant of c-axis and formation of oxygen vacancies.
ASJC Scopus subject areas
- Physics and Astronomy(all)