Characterization of nitrogen-implanted TiO2 nanostructured films

Nanostructured tanium dioxide (TiO2) films were implanted with N+ at 40 keV and ion dose range of 10^16/cm^2 to 4 * 10^16/cm^2, and annealed at temperatures between 673 and 973 K. From XRD and TEM analyses it was found that the anatase phase of TiO2 remained stable up to annealing temperature of 973 K. The samples showed narrower XRD peaks corresponding to larger mean-grain sizes comparing to the un-implanted TiO2 samples. The SIMS depth profile showed a peak of nitrogen concentration at about 60 nm beneath the film surface and this was confirmed using the SRIM-2003 program for simulating ion beam interactions with matter. The absorption spectra of the films as measured using spectrophotometer were found to shift toward longer wavelengths with the increase of ion dose.