Effects of Substrate Temperature on Properties of Transparent Conductive Ta-Doped TiO_2 Films Deposited by Radio-Frequency Magnetron Sputtering

Ta-doped titanium dioxide films are deposited on fused quartz substrates using the rf magnetron sputtering technique at different substrate temperatures. After post-annealing at 550^\circ\!C in a vacuum, all the films are crystallized into the polycrystalline anatase TiO_2 structure. The effects of substrate temperature from room temperature up to 350^\circ\!C on the structure, morphology, and photoelectric properties of Ta-doped titanium dioxide films are analyzed. The average transmittance in the visible region (400–800 nm) of all films is more than 73%. The resistivity decreases firstly and then increases moderately with the increasing substrate temperature. The polycrystalline film deposited at 150^\circ\!C exhibits a lowest resistivity of 7.7\times10^-4 \Omega\cdotcm with the highest carrier density of 1.1\times10^21 cm^-3 and the Hall mobility of 7.4 cm^2\cdot V^-1 s^-1.