Films of nitrogen-doped TiO2 have been successfully deposited on a Si substrate by radio frequency reactive sputtering in a mixture of argon, oxygen and nitrogen. The nitrogen gas ratio varies in the range 0.2–0.4 during the deposition, resulting in TiOxNy films with 3% ≤ y ≤ 6.55% as determined by x-ray photoelectron spectroscopy (XPS). Chemical bond state analysis by XPS indicates that nitrogen is effectively incorporated and produces an oxynitride centre as oxygen is replaced by nitrogen. Characterization by atomic force microscopy demonstrates that the incorporation of nitrogen has a significant effect on the morphology of the targeted TiO2 thin films. Spectroscopic ellipsometry with a photon energy of 0.75–6.5 eV at room temperature has been carried out to derive the refractive index n and the extinction coefficient k on the basis of a new amorphous dispersive model. The optical constants such as absorption coefficient, complex dielectric functions and the optical band gap have been determined. The trend of a decrease in the optical band gap with an increase in nitrogen concentration is consistent with the observation determined by UV–visible spectroscopy. The reduced band gap is associated with the N 2p orbital in the TiOxNy films.
Please check the manuscript for details of any other licences that may have been applied and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (http://uhra.herts.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge. Take down policy If you believe that this document breaches copyright please contact us providing details, any such items will be temporarily removed from the repository pending investigation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.