Optical and magnetic properties of Co-doped TiO2 thin films grown by pulsed laser deposition

Co-doped TiO2 thin films were grown by pulsed laser deposition onto (0 0 0 1)Al2O3 substrates, heated at 310 degrees C, using a KrF excimer laser. The ablation of polycrystalline targets of TiO2 rutile containing a few mol% of Co3O4 was performed in a background gas mixture of argon and hydrogen at total pressure of 10 Pa, for H-2 flow rates of 0.0, 0.1 and 0.2 sccm. X-ray diffraction analysis showed that the as-deposited films consist of TiO2 rutile-based nanocrystallites with preferred orientation along the [1 0 1] direction. The chemical composition of the samples was evaluated by Rutherford backscattering measurements, revealing that Ti distribution is homogeneous on the surface and along film depth, and that the Co:Ti ratio is 0.03:0.97 for all the films investigated. In this paper, we focus on the influence of hydrogen addition to argon background gas on the optical properties of the Co-doped TiO2 films. Results of magnetic characterisation will also be presented. (c) 2006 Elsevier B.V. All rights reserved.