The properties of Ti-doped ZnO films deposited by simultaneous RF and DC magnetron sputtering

Ti-doped ZnO (ZnO:Ti) films have been deposited by simultaneous RF magnetron sputtering of ZnO and DC magnetron sputtering of Ti. The advantage of this method is that the Ti content could be independently controlled. TiO2 was favorable to form with decreasing Ti content. The crystallinity was weakened by increasing the Ti contents, which indicated that the increase of Ti contents made the structure of ZnO:Ti film random. The morphology of ZnO:Ti films was also significantly affected by Ti contents. The carriers of ZnO:Ti films may be originated from oxygen vacancies and Ti donors. The variation in carrier mobility could be due to the ionized impurity scattering and surface morphology. The lower obtained resistivity was 9.69×10−3 Ω cm for ZnO:Ti films with 1.1% Ti. With decreasing Ti contents, the films had higher carrier concentrations and lower optical energy gaps.