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.