Electrical and structural properties of TiO_2- thin film with oxygen vacancies prepared by RF magnetron sputtering using oxygen radical

Anatase TiO_2-δ thin film was prepared by RF magnetron sputtering using oxygen radical and Ti-metal target. Degrees of the TiO_2-δ crystal orientation in the thin film depends of the oxygen gas pressure (PO2 ) in the radical gun. The (004)-and (112)-oriented TiO_2-δ thin films crystallized without postannealing have the mixed valence Ti4+/Ti3+ state. The electrical conductivities, which corresponds to n-type oxide semiconductor, is higher in the case of (004)-oriented TiO_2-δ thin film containing with high concentration of oxygen vacancy. The donor band of TiO_2-δ thin film is observed at >1.0 eV from the Fermi level (EF). The density-of-state at EF is higher in (004)-oriented TiO_2-δ thin film. The above results indicate that the oxygen vacancies can control by changing the PO2 of the oxygen radical.