Influence of doping on the photoactive properties of magnetron-sputtered titania coatings: Experimental and theoretical study

Kevin A. McDonnell, Niall J. English, Mahfujur Rahman, and Denis P. Dowling
Phys. Rev. B 86, 115306 – Published 5 September 2012

Abstract

Titanium dioxide (TiO2) thin films, doped with chromium (Cr) and codoped with chromium-carbon (Cr, C) and chromium-nitrogen (Cr, N) of various concentrations, were deposited using magnetron sputtering. Postdeposition thermal treatments were carried out at 450 °C for 5 h to change the as-deposited amorphous coatings to their crystalline form. The crystalline phase was found to be dependent on the amount and type of dopant present. Ultraviolet-visible (UV-Vis) absorption data and band gap energies calculated by spectroscopic ellipsometry showed that, on increasing Cr concentration, a shift of the absorption edge towards visible light and a reduction of the band gap occurred. This was further improved by codoping of Cr with either N or C, with the latter case exhibiting more photo-activity towards visible light. In addition, hybrid density functional theory (DFT) calculations were performed for Cr-, N-. and C-monodoping, together with Cr-C and Cr-N codoping, in both rutile and anatase phases of crystalline titania. Using this method, absorption coefficients and band gaps were determined to explore photo-activity. Very good, semiquantitative agreement was found between the DFT and experimental approaches for these quantities, underlining the key role of state-of-the-art quantum calculations in interpreting and guiding experimental studies of doping in metal oxides.

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  • Received 2 April 2012

DOI:https://doi.org/10.1103/PhysRevB.86.115306

©2012 American Physical Society

Authors & Affiliations

Kevin A. McDonnell1,2, Niall J. English2,*, Mahfujur Rahman2, and Denis P. Dowling1,2

  • 1School of Mechanical and Materials Engineering, University College Dublin, Belfield, Dublin 4, Ireland
  • 2The SEC Strategic Research Cluster and the Centre for Synthesis and Chemical Biology, School of Chemical and Bioprocess Engineering, University College Dublin, Belfield, Dublin 4, Ireland

  • *Corresponding author: School of Chemical & Bioprocess Engineering, University College Dublin, Belfield, Dublin 4, Ireland; niall.english@ucd.ie

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Issue

Vol. 86, Iss. 11 — 15 September 2012

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