Synthesis and characterization of thin films of metallic oxides and pair oxides based on doped TiO2

Abstract

Thin films of metallic oxides and pair oxides based on doped TiO2 have been characterized using various techniques to study their structural, microstructural, and optical properties. The characterization methods used include X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectrophotometry (UV-Vis), M-line spectroscopy (MLS), atomic force microscopy (AFM), Raman spectroscopy (Raman), and Fourier transform infrared spectroscopy (FTIR). The Zn doped TiO2 thin films were prepared via the Sol-Gel method and deposited on glass substrates using the spin-coating process, followed by thermal treatment at 500°C for 90 minutes. XRD analysis of the undoped TiO2 films revealed the formation of the anatase phase with the A (101) plane as the preferred orientation. Increasing zinc concentrations inhibited crystal growth in the TiO2 films. SEM images of both undoped and Zn doped TiO2 films showed that the addition of zinc significantly altered the microstructure of the TiO2 films. The films exhibited an average transmittance of 70 to 90% in the wavelength range of 350 to 900 nm and an band gap between 3.6 and 3.51 eV. M-lines spectroscopy demonstrated that the Zn: TiO2 planar waveguides support single confined guided modes for both TE and TM polarizations. MLS measurements indicated that zinc doping increases the refractive index, thereby enhancing their waveguiding properties. Additionally, birefringence decreases as the zinc concentration increases up to 7 %wt. Regarding, the thin films of metallic oxides and pair oxides based on TiO2 (ZnO, CuO, ZnO/TiO2 and CuO/TiO2) prepared by the Sol-Gel method (spin-coating) at 500 °C on glass and silicon substrates, their structural properties were studied and identified by Raman spectroscopy analysis. The Rms roughness values of thin films of metallic oxides and pair oxides based on TiO2 were high, indicating that their surface is rougher compared to that of TiO2 single films. Optical observations reveal that the thin films of TiO2, ZnO, and ZnO/TiO2 exhibit high transmittance, ranging from 60 to 80%. In contrast, the thin films of CuO and CuO/TiO2 show low transmittance. Finally, the band gap of thin films of metallic oxides and pair oxides based on TiO2 varies from 3.69 to 4.05 eV.