Polycrystalline and Monocrystalline Pore Arrays with Large Interpore Distance in Anodic Alumina

摘要

We have prepared hexagonally arranged pore arrays with large interpore distance (200-460 nm) by using two kinds of techniques: a self-organization process and a repattern guided anodization on aluminum. The self-organized pore arrays were produced by anodizing aluminum in an aqueous phosphoric acid solution (H_3PO_4:CH_3OH:H_2O = 1:10:89), and show a polycrystalline, i.e., polydomain, feature. Within each domain of several micrometers, the arrays are hexagonally arranged with an interpore distance of 460 nm, while the domains are oriented randomly in plane. A monocrystalline pore array structure with variable interpore distance was prepared based on electron-beam lithography and a subsequent anodization in oxalic acid solution. With a well-designed set of anodization parameters, the prepattern can act as the initiation points and guide the pore growth in the anodic film. Very high aspect ratios (～ 500) can be achieved.