Effects of Power Density and Post Annealing Process on the Microstructure and Wettability of TiO2 Films Deposited by Mid-frequency Magnetron Reactive Sputtering

The relationship of "preparation parameters-microstructures-wettability" of TiO2 films was reported. In this work, TiO2 films were deposited onto glass and silicon substrates by using mid-frequency dual magnetron sputtering technique at ambient temperature with various power densities and deposition time. After de- position, the films were heat treated at different annealing temperatures. X-ray diffraction (XRD), Raman spectroscopy, and field-emission scanning electron microscopy (FE-SEM) were utilized to characterize TiO2 films. The wettability of the films was evaluated by water contact angle measurement. The phase transition temperature of TiO2 films depended on the power density. It was demonstrated that wettability was strongly structure dependent and the film with the thickness of 610 nm (the power density was 2.22 W/cm2) showed the lowest contact angle (8°). It can be concluded that smaller crystallite size, the rutile phase with (110) face being parallel to the surface, and tensile stress favored the hydrophilicity of the TiO2 films.