Fabrication and Characterization of Hydrophilic TiO₂ Thin Films on Unheated Substrates Prepared by Pulsed DC Reactive Magnetron Sputtering

Abstract

TiO 2 thin films were deposited on unheated silicon wafers (100) and glass slides by a pulsed DC reactive magnetron sputtering in an ultrahigh vacuum (UHV) system. The effects of both an operating pressure and deposition time on film structure, surface morphology, and optical property were studied. The film structure and microstructure were characterized by grazing‐incidence X‐ray diffraction (GIXRD) technique and transmission electron microscopy (TEM). The surface morphology was investigated by field emission scanning electron microscopy (FE‐SEM). The optical property of the TiO 2 thin films was determined by spectroscopic ellipsometry (SE). The water contact angle measurement was also used to determine hydrophilicity of the films after exposed to UV light. The results suggested that the TiO 2 thin film at less than 40 nm was amorphous. As the thickness was increased, the mixture of anatase and rutile phases of TiO 2 began to form. By reducing the operating pressure during the film deposition, the rutile phase component can also be enhanced. Both the increased film thickness and decrease operating pressure were the critical factors to improve the hydrophilicity of the TiO 2 thin films.