Fabrication of nanoring arrays by sputter redeposition using porous alumina templates

Ordered arrays of Au, Ni, and Si nanorings have been fabricated using Ar+ sputter redeposition of material in a porous alumina mask. Typical ring dimensions are 50 nm inner diameter and 10-15 nm wall thickness with heights ranging from 50 to 200 nm. Ring composition was confirmed by electron microscopy. Ring diameter, height, and spacing are controllable by varying the process conditions. This process is scalable and parallel, so that highly ordered nanorings over millimeter-sized regions are possible.