Aluminium pre-patterning for highly ordered nanoporous anodized alumina

A pre-patterning method of aluminium surface, in order to obtain highly ordered nanoporous anodized alumina on large areas is presented. Aluminium single crystals have been used as a substrate and a 2D hexagonally closed-packed lattice of shallow pits, with diameter of about 200 nm and period of 350 nm, has been successfully achieved by direct writing laser lithography (DWL) and wet etching. Finally, anodic oxidation of the single crystal at high cell voltage in phosphoric solution results in oxide growth with pore ordering superimposed by the pre-patterning procedure.