Precise Control of Nanohoneycomb Ordering over Anodic Aluminum Oxide of Square Centimeter Areas

Large-area nanoporous anodic aluminum oxide (AAO) films with well-controlled pore ordering are highly desirable for making nanotechnological devices with consistent performance. We report here a novel method to precisely control the ordering of the AAO pores over unprecedented large areas in the square millimeter to square centimeter range. Our experiments show that AAO films grown on large [001]-oriented Al grains in oxalic acid exhibit ideal close packing, whereas those grown on [101] grains do not show any resemblance to close packing. Other orientations give rise to intermediate pore ordering. Thus, through careful conditioning of the orientation of the Al substrate, the AAO pore ordering can be actively controlled, and this method should enable systematic and industrial-scale exploitation of the AAO properties versus pore ordering.