Elaboration and characterization of nano-crystalline layers of transparent titanium dioxide (Anatase-TiO2) deposited by a sol-gel (spin coating) process

Thin films of titanium dioxide (TiO2) were synthesized by sol gel (spin coating) process on glass substrates. The structural, morphological, optical, and electrical properties of TiO2 thin films were examined as a function of solution concentration CS varied between 0.1 M and 0.5 M at 500°C as the annealing temperature. The elaborate samples were characterized by several characterization methods such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV-VISIBLE spectroscopy and two points probe. The obtained results show that the TiO2 samples were crystallized in a tetragonal structure (anatase phase) oriented preferentially along to the (101) plane. The average grain size increases from 34.773 ± 1.738 nm to 48.674 ± 2.433 nm. The FTIR spectrum shows the presence of Ti-O and Ti-O-Ti bonds. The samples are transparent in visible and the indirect optical band gap varies from 3.09 ± 0.154 eV to 3.415 ± 0.170 eV. In addition, the electrical measurements show a minimum electrical resistivity (ρ = 0.18 ± 0.01 Ω.cm) at CS = 0.3 M .