Properties of heavily W-doped TiO2 films deposited on Al2O3-deposited glass by simultaneous rf and dc magnetron sputtering

Abstract TiO 2 films were heavily doped with W (TiO 2 :W) by simultaneous rf magnetron sputtering of TiO 2 , and dc magnetron sputtering of W. The advantage of this method is that the W content could be changed in a wide range. The coexistence of TiO 2 , WO 3 and TiWO 5 in the TiO 2 :W film was detected by XPS analysis. Besides, tungsten in TiO 2 :W film on the bare glass may form mixed valence of W 0+ and W 6+ . Electrical conductivity was primarily due to the contribution of oxygen vacancies and W donors (W Ti ). When the film thickness increased, the TiO 2 :W film showed higher carrier concentration and higher mobility. Furthermore, the resistivity and the transmission decreased obviously with film thickness. On comparing with the TiO 2 :W film deposited on the bare glass, the TiO 2 :W film on the Al 2 O 3 -deposited glass exhibited lower surface roughness, lower resistivity, higher optical energy gap, higher optical transmission, and lower stress-optical coefficient.