Study of Al2O3/TiO2 reflectivity enhancing bi-layer films on bright aluminium substrates

Al2O3/TiO2 bi-layer films on aluminium substrates have been obtained by combining anodising and TiO2 sol–gel deposition. The reflectivity enhancing properties of these Al2O3/TiO2 bi-layer films have been studied in relation to the refractive index and thickness of the Al2O3 and TiO2 single-layers. It is shown that a significant improvement of reflectivity can be achieved by a proper optimisation of the bi-layer elaboration parameters.