Photoelectrochemical Properties of Sb-Doped TiO₂ Film Semiconductor

Abstract

The TiO₂ films doped with various amounts of Sb₂O₃ have been prepared by the sot-gel method and their photoelectrochemical properties have been investigated. The ESCA analysis revealed that antimony atoms in the Ti0₂ (anatase), heated at 600°C for 20 min, were present in the state of Sb³⁺, not of Sb⁵⁺. From the concentration dependences of donor density and resistance of the Sb₂O₃-doped TiO₂ films, the solubility limit of Sb₂O₃ in the TiO₂ (anatase) was estimated to be around 1 mol%. The photocurrent of the TiO₂ films increased up to about 26 mA.cm^-2 by the addition of 0.5 mol% Sb₂0₃, but decreased drastically with further increase in the doping concentration, accompanied by the decrease in the slope of onset photocurrent and the shift of onset potential to the positive side. These phenomena can be explained by the formation of impurity level of SY+ in the band gap of TiO2 which acts as the recombination center. It was further found that Sb₂0₃ in TiO₂ undertook a dissolution reaction by the photogenerated holes under illumination.