Electrochemical/chemical synthesis of nanostructured arrays of oxide cones or rings

Abstract

Quasi-periodic supported arrays of sub-micron sized cones and rings consisting of mixed oxides of Al and Ta have been synthesized by anodization of Al(top)/Ta(bottom) bilayers sputtered on Si substrates and successive etching of the Al oxide and remaining Al-rich features. Exquisite control over the array morphology—cones or rings—is achieved by varying the thickness of the initial Ta layer, in the range of 5 to 50 nm. The nano-cones are formed by the Ta oxide fingering out of the Al oxide as a consequence of the higher mobility of Ta ions, leaving behind a ring with its center exposing the bare substrate.