Improved optical response for N-doped anatase TiO2 films prepared by pulsed laser deposition in N2/NH3/O2 mixture

Nanostructured N-doped TiO2 films in anatase phase were prepared by laser ablation of titanium target in N-2/O-2 and NH3/N-2/O-2, respectively. The films were deposited on glass Substrates which were heated to 400 degrees C. The as-deposited films were characterized by Xray photoetectron spectroscopy (XPS), Raman spectroscopy and atomic force microscope (AFM). Nitrogen doping is more efficient when adding a little NH3 into N-2/O-2 mixture. The nitrogen concentrations are 2.0% and 4.4% for the films deposited in N-2/O-2 and NH3/N-2/O-2, respectively. A remarkable improvement of optical absorption in the visible light region has been detected for the film deposited in NH3/N-2/O-2. The mechanism for the redshift in photoabsorption spectra of N-doped TiO2 films has been discussed. (c) 2005 Elsevier B.V. All rights reserved.