INFLUENCE OF THE SUBSTRATE TEMPERATURE ON TiO2 THIN LAYERS DEPOSITED BY THE DIRECT CURRENT MAGNETRON SPUTTERING TECHNOLOGY

In this study, Anatase thin films of titanium dioxide (TiO2) are deposited by the Direct Current (DC) magnetron sputtering technique on glass substrate for future application in gas sensors. In our work, we focused and discussed the effect of various substrate temperatures 200∘C, 400∘C and 450∘C, and film thicknesses 142, 220 and 410nm, respectively, in order to study the structural and optical properties of the TiO2 thin films. The crystalline structure and optical properties of TiO2 nanoparticles were investigated using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Atomic Force Microscopy (AFM), Raman spectroscopy and UV–visible spectroscopy. The formation of the Anatase TiO2 with Tetragonal crystal structure has been confirmed with XRD. UV–visible spectrophotometry characterization of the developed thin films showed that all the films had an optical transmission greater than 92% in the visible region. In addition, the obtained direct and indirect optical band gaps using the Tauc plot are 3.66, 3.34eV at 200∘C 3.74, 3.37eV at 400∘C and 3.71, 3.37eV at 450∘C, respectively. Forouhi–Bloomer (FB) physical model has been used to obtain the refractive index and extinction coefficient by fitting theoretical transmittance curves to experimental ones. The optical refractive index is found to vary from 2.350 for 200∘C, 2.1499 for 400∘C and 2.1420 for 450∘C. Moreover, we have obtained an extinction coefficient k (λ) of around 3.71×10−3 for both substrate temperatures 200∘C and 400∘C, and around 1.043×10−3 for the 450∘C.