Fabrication of Highly Ordered Cylindrical Nanopores with Modulated Diameter Using Anodic Alumina

We propose two novel methods for fabrication of highly ordered cylindrical nanopores with modulated diameter using anodic aluminum oxide (AAO) template. These are (a) multistep anodization in which each step is separated from the next by a controlled wet etching process, and (b) lateral hard anodization of aluminum in malonic acid. This latter method also circumvents the typical sample burning problem which always accompanies surface hard anodization. Further, this method enables high temperature, high voltage anodization studies without requiring a buffer layer of aluminum oxide on the surface.