Anatase phase TiO2 thin films obtained by pulsed laser deposition for gas sensing applications

Anatase phase titanium dioxide (TiO2) thin films were grown by pulsed laser deposition on 〈0 0 1〉 SiO2 substrates. An UV KrF* (λ = 248 nm, τFWHM ≅ 20 ns, ν = 2 Hz) excimer laser was used for the irradiation of the TiO2 targets. The substrates were kept at room temperature or heated during the film deposition at values within the 100-500 °C range. The crystalline quality of the films and their chemical composition were investigated by X-ray diffractometry and energy dispersive X-ray spectroscopy. The optical properties were studied by a double beam spectrophotometer in the spectral range of 400-1200 nm. At substrate temperatures higher than 300 °C, the structure of the deposited thin films changes from poorly to well crystallised, corresponding to the tetragonal TiO2 anatase phase. The average optical transmittance in the visible-infrared spectral range of the films is higher than 85% which makes them suitable for sensor applications.