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

Sol-gel TiO2 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 degreesC for 2 h. The appearance of the rutile phase depends on the substrate used. For example, the rutile phase appeared at 700 degreesC in the xerogel while the presence of substrate Si(100) stabilizes the anatase phase up to 800 degreesC. 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 degreesC, increasing to around 40 nm at 800 degreesC. (C) 2002 Elsevier Science BN All rights reserved.