Iron Doped Titania Thin Films Prepared by Spin Coating

Thin films of titania (TiO₂) doped with 1–5 wt-%Fe were spin coated on glass slides and then annealed at 500°C for 2 h. Results revealed that all of the films were ∼500 nm in thickness and consisted of anatase. Increasing the dopant levels revealed the following trends: the major (101) anatase peak shifted to larger lattice spacing [the peaks were normalised using the principal (210) chromium coating peak as an in situ standard]; the microstructures showed increasing shrinkage cracking, a phenomenon that has not been reported previously; the optical transmittance generally decreased; the amplitude of the transmittance curves generally decreased; and the optical indirect band gap decreased from 3·40 to 3·18 eV, possibly due to silicon contamination, residual thermal stress and/or the formation of midgap states from Fe doping.