Optical Properties of Sputter Deposited Transparent and Conducting TiO2:Nb Films

Transparent and conducting thin films of TiO2:Nb were prepared on glass by reactive dc magnetron sputtering in Ar + O-2. Post-deposition annealing in vacuum at 450 degrees C led to good electrical conductivity and optical transparency. The optical properties in the sub-bandgap region were in good agreement with Drude free electron theory, which accounts for intraband absorption. The band gap of the films was found to be in the range of 3.3 to 3.5 eV and signifies the onset of interband absorption. Electrical conductivities in the 10(-3) Omega cm range were obtained both from dc electrical measurements and from analysis of the optical measurements