The influence of titanium on the properties of zinc oxide films deposited by radio frequency magnetron sputtering

TiO2-doped zinc oxide thin films were deposited on glass substrates by radio frequency (RF) magnetron sputtering with TiO2-doped ZnO targets in an argon atmosphere. The structural properties of TiO2-doped ZnO films doped with different TiO2 contents were investigated. The experimental results show that polycrystalline TiO2-doped ZnO films had the (0 0 2) preferred orientation. The deposition parameters such as the working pressure and substrate temperature of TiO2-doped ZnO films were also investigated. The crystalline structure of the TiO2-doped ZnO films gradually improved as the working pressure was lowered and the substrate temperature was raised. The lowest electrical resistivity for the TiO2-doped ZnO films was obtained when the Ti addition was 1.34 wt%; its value was 2.50 × 10−3 Ω cm, smaller than that found in previous studies. The transmittance of the TiO2-doped ZnO films in the visible wavelength range was more than 80%. The optical energy gap was related to the carrier concentration, and was in the range of 3.30-3.48 eV.