TiO2 thin films were synthesized by the sol-gel method and spin coating
process. The calcination temperature was changed from 100 to 550 °C. XRD
patterns show increasing the content of polycrystalline anatase phase with
increasing the calcination temperature. The AFM results indicate granular
morphology of the films, which particle size changes from 22 to 166 nm by
increasing the calcination temperature. The RBS, EDX and Raman spectroscopy
of the films show the ratio of Ti:O ~0.5, and diffusion of sodium ions
from substrate into the layer, by increasing the calcination temperature.
The UV-vis spectroscopy of the films indicates a red shift by increasing the
calcination temperature. The contact angle meter experiment shows that
superhydrophilicity of the films depends on the formation of anatase crystal
structure and diffused sodium content from substrate to the layer. The best
hydrophilicity property was observed at 450 °C calcination temperature,
where the film is converted to a superhydrophilic surface after 10 min
under 2 mW/cm2 UV irradiation. Water droplet on TiO2 thin film on
Si(111), Si(100), and quartz substrates is spread to smaller angles rather
than glass and polycrystalline Si substrates under UV irradiation.