The effect of ion source working power on the composition and optical properties of TiO2 films bombarded by N ion beam

At room temperature, the titanium dioxide (TiO2) films were deposited by the direct current pulse magnetron sputtering. Then the TiO2 films were in-situ bombarded by the N ion beam, which doped the N ions into the TiO2 films. By this way, the N doped TiO2 (N–TiO2) films were prepared. Varying the working power of the ion source, the N–TiO2 films with different composition and properties were obtained. Characterization by X-ray photoelectron spectrometry showed that the N ions mainly reacted with Ti to formed OTiN bonds and the doping depth exceeded 100 nm. With the working power of ion source in 150 W, the atom percent of N, mean absorbency in visible range, and band gap could reach at the optimal value, which was 22.9 at.%, 44.6%, and 2.81 eV, respectively. With increasing the working power of ion source, the atom percent of N and the mean absorbency in visible range, as well as the band gap, decreased and increased, respectively. With these results, one conclusion could be deduced that the composition and optical properties of N–TiO2 films could be influenced by the N atom percent and chemical bond structure of Ti, which in turn was controlled by the working power of N ion source.