Electrical-bridge model on the self-organized growth of nanopores in anodized aluminum oxide

Anodic aluminum oxide (AAO) has attracted a lot of attention for its application on the template-synthesis of nanomaterials. Highly ordered AAO template is essential to its applications. Here, we propose an electrical-bridge model based on the analysis of carrier ion drifts in the oxide layer and the electrical-field distribution. This model can elucidate the AAO growth mechanism, and allow better understanding of the nature of the nanopore self-organization during the anodic formation of AAO. The electrical-field distribution was greatly affected by the thickness of the oxide layer that is determined by the radii of cell and nanopore. The variable bridge resistances are related to anodizing conditions, such as temperature, which influence the ordering. The nanopores acquire uniformity by self-adjustment via the electrical bridge. Based on this model, the formation of hexagonal morphology of AAO, which is more stable than other arrangements, becomes a natural result of self-organization and the effect of anodizing conditions on the ordering is elucidated.