Polycrystalline and monocrystalline pore arrays with large interpore distance in anodic alumina

We have prepared hexagonally arranged pore arrays with large interpore dist ance (200-460 nm) by using two kinds of techniques: a self-organization pro cess and a prepattern guided anodization on aluminum. The self-organized po re arrays were produced by anodizing aluminum in an aqueous phosphoric acid solution (H3PO4:CH3OH:H2O = 1:10.89), and show a polycrystalline, i.e., po ly-domain, feature. Within each domain of several micrometers, the arrays a re hexagonally arranged with an interpore distance of 460 nm, while the dom ains are oriented randomly in plane. A monocrystalline pore array structure with variable interpore distance was prepared based on electron-beam litho graphy and a subsequent anodization in oxalic acid solution. With a well-de signed set of anodization parameters, the prepattern can act as the initiat ion points and guide the pore growth in the anodic film. Very high aspect r atios (similar to 500) can be achieved. (C) 2000 The Electrochemical Societ y. S1099-0062(99)08-058-X. All rights reserved.