Preparation and characterization of nitrogen-incorporated SnO2 films

Nitrogen-incorporated SnO2 thin films have been grown on Si(100) and quartz substrates by reactive sputtering of a Sn target in gas mixtures of N2–O2. The structure of the nitrogen-incorporated SnO2 thin films was studied by X-ray diffraction, and the changes in the chemical bonds and atomic binding states of the nitrogen-incorporated SnO2 thin films were analyzed by X-ray photoelectron spectroscopy. It was found that the binding energy of Sn 3d and O 1s shifts 0.65 eV and 0.35 eV, respectively, toward the lower-energy side after nitrogen was incorporated into the SnO2 thin films as a comparison with that of pure SnO2 film. The indirect optical band gap gradually decreases from 3.42 eV to 3.23 eV, i.e. from the UV to the edge of the visible-light range, with increasing nitrogen flux content in the N2–O2 gas mixtures.