Ordered anodic alumina nanochannels on focused-ion-beam-prepatterned aluminum surfaces

A combined process of electropolishing, focused-ion-beam lithography, and controlled anodization is used to fabricate anodic alumina films with ordered nanochannels. The ion beam is used to create a hexagonally close-packed lattice of concaves on a polished aluminum surface and the concaves act as pinning points for guiding the growth of nanochannels in the following anodization step. By carefully matching the lattice constant (100 nm) with the anodization voltage, ordered nanochannels with aspect ratio of similar to 100 are fabricated. The effects of the ion dose and its corresponding depth of the concaves on the ordering of the nanochannel array are investigated and a minimum depth of 3 nm is found to be necessary for effective guidance of the growth of ordered nanochannels. (C) 2001 American Institute of Physics.