UV photo-annealing of thin sol-gel films

Thin gel films based on hydrolyzed alkoxycompounds such as TEOS or TEOTi can be annealed at low temperature (T ≈ 100°C) by irradiation with UV light (λ < 200 nm). Condensation reactions such as the reaction between hydroxyl groups are accelerated and the polymeric species in the gel film are decomposed into smaller fragments. The gel phase in the sol-gel deposition process can be omitted when hydroxyl radical generating species such as nitric acid are present. Easier processing and better film quality can be obtained. UV photoannealing creates also the possibility to synthesize new compounds by allowing heterogeneous condensation reactions in sol-gel systems.