Structural defects and electronic structure of N-ion implanted TiO 2 : Bulk versus thin film

Systematic investigation of atomic structure of N-ion implanted TiO 2 (thin films and bulk ceramics) was performed by XPS measurements (core levels and valence bands) and first-principles density functional theory (DFT) calculations. In bulk samples experiment and theory demonstrate anion N → O substitution. For the thin films case experiments evidence valuable contributions from N 2 and NO molecule-like structures and theoretical modeling reveals a possibility of formation of these species as result of the appearance of interstitial nitrogen defects on the various surfaces of TiO 2 . Energetics of formation of oxygen vacancies and its key role for band gap reduction is also discussed. © 2015 Elsevier B.V. All rights reserved