Preparation of TaON thin films by nitridation of solution process-derived precursor films with urea

Tantalum Oxynitride (TaON) has been recognized as a visible-light photocatalyst, and is thus expected to be applicable to semiconductive and transparent conductive film. In this study, TaON thin films were prepared on a silica glass substrate by nitridation of Ta₂O₅ precursor films using urea. The precursor Ta₂O₅ films were prepared from Ta(OC₂H₅)₅. Then, urea and the precursor Ta₂O₅ thin film were placed at the upstream and downstream sides in a tube furnace, respectively, and heated under a nitrogen flow to supply the vaporized urea constituent to the surface of the Ta₂O₅ precursor film. Thin film of β-TaON was obtained by a heat treatment at 1000 °C with urea under nitrogen flow. The transmittance of the film was 70 ~ 80% in the wavelength region from 500 to 800 nm, and the optical bandgap of the film was 2.65 eV.