Three-dimensionally nanostructured alumina film on glass substrate: Anodization of glass surface

We report fabrication of a three-dimensionally nanostructured porous alumina film on a glass substrate exhibiting an angle-insensitive optical transmission property using a robust anodization with ‘fictive critical anodizing-voltage’ estimation technique. The fictive critical anodizing-voltage is estimated from a resistance profile curvature; it offers a limit of a maximum cell size of an anodization system. Using this technique, we have obtained an extra-large cell (over 1 μm) and thick (∼2.5 μm) alumina film. Observation of a fine structure on the current density profile at the initial anodizing stage is also presented with resistance profiling, cross-sectional scanning and transmission electron microscopies.