Conversion Model for Evaluating the Surface and Pore-Bottom Porosity of Anodic Aluminum Oxide on a Unified Scale

抄録

Porosity in anodic aluminum oxide (AAO) is one of the key structural features in the research and development of AAO-based nanostructured devices. Although surface image analysis (SIA) using scanning electron microscopy is commonly used to measure porosity, it tends to underestimate this value because of inherent systematic errors and transient surface structures. In addition, the tendency of pores to adopt a tapered shape during high-throughput, high-temperature anodization requires accurate structural measurements. In this study, we derived a theoretical formula for calculating the effective surface porosity P_top. We assessed its consistency by quantitatively comparing the apparent surface porosity from SIA and the pore-bottom porosity P_bottom measured using the pore-filling method. The formula proposed in this study enables a direct comparison of P_top and P_bottom on a unified scale. This achievement contributes to the efficient fabrication of samples through high-temperature anodization and improves the structural design of AAO-based research and application devices.