Fabrication and characterization of Fe 3+-doped titania semiconductor electrodes with p–n homojunction devices

Abstract

The nano-TiO 2 electrode with a p–n homojunction device was designed and fabricated by coating of the Fe 3+-doped TiO 2 (p-type) film on top of the nano-TiO 2 (n-type) film. These films were prepared from synthesized sol–gel TiO 2 samples which were verified as anatase with nano-size particles. The semiconductor characteristics of the p-type and n-type films were demonstrated by current–voltage ( I– V) measurements. Results show that the rectifying curves of undoped TiO 2 and Fe 3+-doped TiO 2 sample films were observed from the I– V data illustration for both the n-type and p-type films. In addition, the shapes of the rectifying curves were influenced by the fabrication conditions of the sample films, such as the doping concentration of the metal ions, and thermal treatments. Moreover, the p–n homojunction films heating at different temperatures were produced and analyzed by the I– V measurements. From the I– V data analysis, the rectifying current of this p–n junction diode has a 10 mA order higher than the current of the n-type film. The p–n homojunction TiO 2 electrode demonstrated greater performance of electronic properties than the n-type TiO 2 electrode.