Periodic Holes with 10 nm Diameter Produced by Grazing Ar+ Milling of the Barrier Layer in Hexagonally Ordered Nanoporous Alumina

• Published in: Nano letters 2002-01, Vol.2 (1), p.37-41
• Main Authors: Xu, Tao, Zangari, Giovanni, Metzger, Robert M
• Format: Article
• Language: English
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl010075g

Long-term anodization of aluminum provides a hexagonally ordered array of nanopores with very uniform pore diameters (between 30 and 50 nm, depending on pH, acid, and potential) and pore spacings of 80 to 100 nm within a matrix of amorphous aluminum oxide. However, one often desires smaller diameters. Because the bottom of each pore is U-shaped, we can use this geometrical feature and gradually open the U-shaped bottom cap of the alumina nanochannel by controlled grazing angle Ar+ ion milling and thus form smaller pore apertures. In initial results, we prepared opened holes with a diameter as small as 10 nm. This opens the door to numerous applications that need small but hexagonally periodic features produced by inexpensive means.