Defects and doping in oxides: case of doped TiO2 films

Oxide-based films and nanostructures have emerged as important and promising materials for a wide range of applications such as photovoltaics, photocatalysis, optoelectronics, gas sensing and electronics. To develop an appropriate understanding of the properties of these oxides, it is necessary to address the material preparation methods as well as structural and defect issues. The present work deals with oxide films synthesis processes using radio-frequency sputtering technique, the film stoichiometry control and structural defect identifying, to produce transparent and conductive films. Nb-doped titanium oxide (TiO2:Nb) thin films are considered. A comparative study of the electrical and optical properties of the Nb:TiO2 thin films in relation with the film chemical properties, structural defects and crystalline phase, the target material and the sputtering gas was made. The lowest resistivity was achieved in the range 2×10-3 -7.42×10-4 Ω.cm, which makes the used deposition method a suitable technique for the development of transparent electrodes, transferable also to large areas.