Nano-quantum size effect in sol-gel derived mesoporous titania layers deposited on soda-lime glass substrate

The TiO2 nanolayers were fabricated on soda-lime glass substrates with the application of sol-gel method and dip-coating technique. In the fabricated TiO2 layers, the quantum size effect can be observed. For the sake of comparison, we investigated also the TiO2 nanolayers fabricated on soda-lime glass substrates with a buffer silica layer. The fabricated layers were investigated with the application of optical measurement techniques and atomic force microscopy. The widths of energy gap and Urbach energy were determined. The diffusion of sodium ions Na+ from the glass substrate to the TiO2 layer brings about the non-monotonic dependence of the energy band gap on the thickness of TiO2 layer. In the TiO2 layers fabricated on soda-lime glass substrates pre-coated with a SiO2 layer, the influence of silicon ions on the direct energy band gap was found.