Electrical conductivity and photoconductivity studies of TiO2 sol–gel thin films and the effect of N-doping

Several sol–gel TiO2 thin films, N-doped and undoped, were prepared using the dip-coating technique. Dark conductivity in vacuum and in air gives information on the role of the adsorbed oxygen or water and the influence of nitrogen. Transient photoconductivity in vacuum and in air was studied with illumination time for various light intensities and found to be very sensitive to the environment. The rise and decay are much faster in air than in vacuum, suggesting the predominant mechanism of conduction in each case. The role of the presence of nitrogen is also discussed.