Elaboration and characterization of thin films of TiO2 prepared by sol–gel process

Abstract Sol–gel TiO 2 thin films have been obtained by a dip-coating method on a silicon substrate. Very stable sols of this oxide were synthesized using the alkoxide Ti( O -nBu) 4 in the presence of acetic acid and using acetylacetone as a chelating agent. The film thickness varied from 20 to 100 nm depending on the concentration of the sol for a monolayer thin film. The structural characterization of this film on substrate Si(100) shows that the titanium oxide anatase phase is formed after heating at 400 °C for 2 h. The appearance of the rutile phase depends on the substrate used. For example, the rutile phase appeared at 700 °C in the xerogel while the presence of substrate Si(100) stabilizes the anatase phase up to 800 °C. The influence of the annealing temperature on grain size has been evidenced. Indeed, the size of the particles found equal to 4 nm for films annealed at 400 °C, increasing to around 40 nm at 800 °C.