Electrical properties and defect chemistry of indium-doped TiO2 : thermoelectric power

This work studied the effect of indium on the semiconducting properties of TiO2 (rutile) at elevated temperatures (1023–1273 K) in the gas phase of controlled oxygen activity in the range of 10−16 Pa < p(O2) < 105 Pa. The studies were performed using the measurements of thermoelectric power of In-doped TiO2 (0.4 at.% In) as a function of oxygen activity and temperature. The obtained data indicates that indium is incorporated into the TiO2 lattice according to the dual mechanism leading to the formation of donors and acceptors in the interface (surface and grain boundary) layer and the bulk phase, respectively. This effect is considered in terms of a quasi-isolated surface layer that differs from the bulk phase in terms of semiconducting properties and the related defect disorder.