Photocatalytic titanium dioxide thin films prepared by reactive pulse magnetron sputtering at low temperature

An innovative reactive pulse magnetron sputtering (PMS) system allowing to change the pulse mode (unipolar, bipolar or pulse packet) has been used to deposit TiO2 films at dynamic deposition rates of 8...50 nm m/min. Photo-induced hydrophilicity and photocatalytic degradation by UV-A illumination were investigated by measuring the decrease of the water contact angle and the decomposition of methylene blue organic dye, respectively. It was observed that using the PMS technology the TiO2 layers can be deposited in situ crystalline at temperatures much lower than the necessary annealing temperature for amorphous deposited layers. Moreover, these in situ crystalline deposited layers have superior photocatalytic properties to that of amorphous deposited post-annealed TiO2 layers. Thin TiO2 films (<50 nm) deposited at substrate temperatures as low as 130 °C exhibit sufficient photocatalytic activity for many applications.