Fabrication and property of titanium dioxide thin film using sol-gel method and CO₂ 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 TiO ₂ 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 3.0W, 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 350-800nm. 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.