A comparative study on the structural, optical, and electrical properties of titania films grown by spin-coating method

We report the annealing temperature dependence on the physical properties of TiO₂ (titania) thin films grown using solgel spin-coating method for various concentrations of precursors and stabilizers. X-ray diffraction (XRD) and atomic force microscopy (AFM) images, respectively, provided the structural properties and surface morphology of the films. The XRD results confirm the anatase phase in the films, and a comparative study on morphology has shown that the better uniformity and lower roughness in the films grown at 350 °C compared to films grown at 450 °C for different concentrations. The optical properties of titania thin films were investigated by UV–Vis transmittance and photoluminescence (PL) spectra. All the films exhibited high transmittance, and the indirect bandgap obtained for the films annealed at 350 °C and 450 °C varies between 3.45 and 3.34 eV. The PL spectra provide information regarding defect states in the film for different concentrations. The electrical resistivity of the sample with molar ratio 0.2:0.4 M film decreased for both temperatures compared to other samples.