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Title: The electronic structure changes and the origin of the enhanced optical properties in N-doped anatase TiO{sub 2}—A theoretical revisit

We have investigated the electronic structure changes and the origin of the enhanced optical properties of N-doped anatase TiO{sub 2} using first-principles density-functional theory calculations. To determine the band gap variations induced by N-doping, we developed a new approach to locate the effective valence band maximum (VBM) by characterizing the degree of localization of the N-induced states in the band structures of various N-doped TiO{sub 2} systems. Our calculations show that the band gap variations are largely affected by the local bonding structures and doping concentration of the substitutional N atoms. As the N content is up to certain level, some local bonding structures can indeed cause band gap reduction due to the formation of band-like delocalized states above the VBM of TiO{sub 2}, while other local bonding configurations may simply form localized impurity states in the band gap. Accordingly, the N-induced localized and delocalized electronic states can exist simultaneously to contribute to the enhanced optical properties of anatase TiO{sub 2}. Our computational approach also provides a new way to investigate the band gap engineering of other wide band gap semiconductor material systems.
Authors:
; ;  [1]
  1. Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)
Publication Date:
OSTI Identifier:
22314392
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 9; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CONCENTRATION RATIO; DENSITY FUNCTIONAL METHOD; DOPED MATERIALS; ELECTRONIC STRUCTURE; OPTICAL PROPERTIES; ORIGIN; SEMICONDUCTOR MATERIALS; TITANIUM OXIDES