XPS Study of N-doped TiO_x Thin Films Prepared By DC Reactive Magnetron Sputtering

Abstract

The N-doped TiOx films, coated on glass substrates, were prepared by DC reactive magnetron sputtering using Ti metal target in a mixture of Ar, O2 and N2. The dependence of the films composition on ratio of N2 partial pressure to total pressure was investigated using X-ray photoelectron spectroscopy (XPS). The XPS results show that N1s line is composed of three peaks at the binding energies of 396.0±0.2eV, 399.9±0.2eV and 402.0±0.4eV, respectively; for an increasing ratio two regimes are observed. For the ratio between 0.01 and 0.05, with the increase of the ratio, the N1s concentration at 396.0±0.2eV increases from 0.002 to 0.007 and the O1s concentration at 531.9±0.2eV increases from 10.8 to 62.7; for the ratio between 0.05 and 0.11, with the increase of the ratio, the N1s concentration at 396.0±0.2eV decreases from 0.007 to 0.003 and the O1s concentration at 531.9±0.2eV decreases from 62.7 to 18.7. The O1s at a binding energy 531.9±0.2eV corresponds to hydroxyl groups. With the increase of the ratio, the atomic ratio O/Ti varies from 1.98 to 1.93, and the chemical state of the Ti is kept at Ti. The more N1s at 396.0±0.2eV, the more O1s at 531.9±0.2eV, that is, more hydroxyl groups (OH) on the surface of the N-doped TiO2 film.