A. Nakaruk

Fe-doped and Mn-doped titanium dioxide thin films

Thin films of TiO2 doped with Fe and Mn were deposited on F-doped SnO2-coated glass by spin coating. Dopant concentrations of 3–7xa0wt% (metal basis) were used. The structural, chemical, and optical characteristics of the films were investigated. Laser Raman microspectroscopy and glancing angle X-ray diffraction data showed that the films consisted of the anatase polymorph of TiO2. X-ray photoelectron spectroscopy data indicated the presence of Fe3+, Mn4+, and Mn3+ in the doped films, as predicted by calculated thermodynamic stability diagrams, and the occurrence of atomic disorder and associated structural distortion. Ultraviolet–visible spectrophotometry data showed that the optical indirect band gap of the films decreased significantly with increasing dopant levels, from 3.36xa0eV (undoped) to 2.95xa0eV (7xa0wt% Fe) and 2.90xa0eV (7xa0wt% Mn). These improvements are attributed to single (Fe) or multiple (Mn) shallow electron/hole trapping sites associated with the dopant ions.

Iron doped titania thin films prepared by spin coating

Abstract 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.

Deposition rate of anatase films by ultrasonic spray pyrolysis

Abstract Abstract Fully dense, transparent, submicron, polycrystalline, anatase thin films, deposited for 30-120u2005min on glass slides heated at 400°C, were prepared by ultrasonic spray pyrolysis using titanium butoxide dissolved in methanol. The films were characterised using laser Raman microspectroscopy, single beam focused ion beam milling and ultraviolet-visible (UV-Vis) spectrophotometry in order to assess the mineralogy, thickness and transmittance respectively. The thin films showed increasing thickness and roughness but decreasing transmittance as the deposition time increased. There do not appear to be any published kinetics data for the deposition of such films. Consequently, what was found to be a linear growth rate was determined to be 11u2005nmu2005min−1 (∼0·18u2005nmu2005s−1).