Figure 1.

Three-dimensional schematic view showing the main steps of three type niobia nanostructured films production via porous alumina assisted anodizing of systems Al/Nb on glass substrate: (a) sputter deposition of Al/Nb bilayer; (b) anodizing the Al layer to form porous alumina film; (c) porous alumina assisted anodizing of the Nb layer; (d) porous alumina assisted high voltage reanodizing of the Nb layer on glass substrate to grow niobia (first type, native film); (e) planarization of niobia film by removal of the unfilled porous alumina portion (second type, planarized film); (f) completely removal of the porous alumina (third type, column-like film).