Fabrication and property of titanium dioxide thin film using sol-gel method and CO laser annealing

In this Letter, the sol-gel method and CO₂ laser annealing are combined as an effective process for studying phase formation and the hydrophilic property of TiO₂ thin film. X-ray diffraction patterns reveal that phase transformation can be controlled by sol-gel solution or laser power. ANSYS software was used to analyse the temperature field during laser treatment processing to confirm the phase transformation temperature of TiO₂ for anatase at 350°C and rutile at 800°C. Contact angle is an index of hydrophilicity of films and related to laser power. As laser power increases from 0.5 to 3.0°W, the contact angle of the film decreased from 70° to 45° because of the enhanced hydrophilicity. The photoluminescence (PL) property of the laser annealed films was also studied to find wavelengths of 350°800°nm. The wide PL can be deconvoluted into different peaks that were attributed to the lattice emission, deep-level emissions from oxygen vacancies and defect states. This combined processing offers an easy way for the fabrication of hydrophilic and wide PL TiO₂ with merits of larger area, selective treatment and low cost.