Titanium oxide thin layers deposed by dip-coating method: Their optical and structural properties

TiO2 thin films were prepared by sol-gel method. The structural investigations performed by means of X-ray diffraction (XRD) technique and scanning electron microscopy (SEM) showed the shape structure at T = 600 °C. The optical constants of the deposited film were obtained from the analysis of the experimentally recorded transmittance spectral data in the wavelength of 200–3000 nm range. The values of some important parameters of the studied films are determined, such as refractive index n and thickness d. In this work, using the transmission spectra, we have calculated the dielectric constant (ε∞) for four layered TiO2 films; a simple relation is suggested to estimate the third-order optical nonlinear susceptibility χ(3). It has been found that the dispersion data obeyed the single oscillator of the Wemple–DiDomenico model, from which the dispersion parameters and high-frequency dielectric constant were determined. The estimations of the corresponding band gap Eg, χ(3) and ε∞ are 2.57 eV, 0.021 · 10−10 esu and 5.20, respectively.