Effect of niobium on the structure of titanium dioxide thin films

• Published in: Thin solid films 2006-07, Vol.510 (1), p.119-124
• Main Authors: Sheppard, L., Bak, T., Nowotny, J., Sorrell, C.C., Kumar, S., Gerson, A.R., Barnes, M.C., Ball, C.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Defects and impurities in crystals; microstructure; Deposition by sputtering; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Growth mechanism; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Point defects (vacancies, interstitials, color centers, etc.) and defect clusters; Solubility, segregation, and mixing; phase separation; Sputtering; Structure of solids and liquids; crystallography; Titanium oxide; X-ray diffraction
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2005.12.272

This paper reports the effect of niobium on the structure of titanium dioxide (TiO 2) thin films deposited on glass. The results obtained indicated that the direct current (DC) co-sputtering of Ti and Nb onto glass substrates in the presence of oxygen results in the formation of Nb-doped anatase thin films with strong preferential orientation. In the concentration range between 0 and 40 at.% Nb, niobium is incorporated into the TiO 2 lattice according to a substitution mechanism, entering Ti sites in the cation sub-lattice. No evidence exists for a solubility limit < 40 at.% of Nb under the applied deposition conditions, however, it is not believed that an equilibrium situation prevails. Lattice charge compensation was concluded to occur by the formation of cation vacancies for samples with up to 10 at.% Nb, and by Ti 3+ or Nb 4+ ions for the samples with ≥ 15 at.% Nb, the latter in conjunction with cation vacancy compensation.