Variation of structural and optical properties of TiO2 films prepared by DC magnetron sputtering method with annealing temperature

TiO2 thin films are deposited by direct current magnetron sputtering method on the silicon and quartz substrates. The effect of annealing temperature on the film properties are analysed by using X-ray diffraction (XRD), Raman scattering, atomic force microscopy (AFM), scanning electron microscopy (SEM) and optical spectroscopy measurements. Raman and XRD results reveal that the crystal structure of the TiO2 film is strongly affected by the annealing temperature. The crystal structure of the coated film is changed from amorphous to anatase structure after annealing at 500 degrees C. Anatase and rutile phases of TiO2 start to coexist after annealing at 800 degrees C. Rutile phases of TiO2 become dominant for film annealed at 900 degrees C. SEM and AFM images uncover that the morphology, grain size and surface roughness of TiO2 films vary with the annealing temperature. The optical band gap decreases from 3.35 to 2.90 eV as the phase transforms from amorphous to rutile.