Magnetron sputtering of TiOxNy films

This article reports on the characterization and preparation of N-doped titanium dioxide (TiO2) films by reactive magnetron sputtering from Ti(99.5) targets in a mixture of Ar/O2/N2 atmosphere on unheated glass substrates. A dual magnetron system supplied by a dc bipolar pulsed power source was used to sputter the TiOxNy films. The amount of N in the TiOxNy film ranges from 5 to 40 at%. Its structure was measured using X-ray diffraction (XRD), the optical band gap was calculated from Tauc plots and the decrease of the water contact angle αir after the film activation by UV irradiation was investigated as a function of at% of N in the TiOxNy film. The yellow-coloured TiOxNy films with high (≈8 at%) amount of N exhibited a strong decrease of the band gap Eg down to 2.7 eV. A significant decrease of the water contact angle αir after UV irradiation has been observed for 2 μm thick transparent nanocrystalline (anatase+rutile) N-doped TiO2 films containing less than 6 at% of N.