Investigation of the lattice defects density and optical characteristics for the anatase phase of titanium dioxide nanocrystalline films

The spin-coating sol-gel method was used and the nanocrystallines of titanium dioxide were deposited on the ordinary glass slide substrates. The films were annealed in air at temperature range between 350 and \(550\,\,^{\circ }\hbox {C}\) and the scanning electron microscopy images of them were analyzed to study the morphology as well as the thickness of films in terms of shape and size distribution behavior of embedded nanoparticles. The behavior of distribution functions was applied; the X-ray diffraction patterns were simulated and compared to the measured \(\hbox {TiO}_2\) peak profiles, using the advanced X-ray diffraction analysis. The volume weighted average crystallite size and the density of linear lattice defects were investigated as a function of annealing temperature. The transmittance spectra of our \(\hbox {TiO}_2\) films were taken by spectrophotometer and the film thicknesses as well as the optical energy gap were calculated. It is found that the film thickness of our samples is in the range of 343–397 nm which is in agreement with the SEM-cross section results. It is also seen that with the elevation of annealing temperature, the energy gap of films decreases. Finally, the correlation between the optical band gap and microstructure parameters (i.e., crystallite size, dislocation density as well as the strain along the z direction) and optical characteristics was studied.