Formation of alumina films with nano-dot structures by successive liquid phase deposition, anodizing, and substrate dissolution


Correspondence to: M. Sakairi, Hokkaido University, Faculty of Engineering, Japan.



A process based on successive anodizing, liquid phase deposition (LPD), re-anodizing, and aluminium substrate dissolution to form alumina films with nano-dot structures is demonstrated. Initially, a protective oxide film is formed on the aluminium surface to prevent further dissolution of the aluminium substrate during LPD processing. Because of heterogeneity in the protective oxide film, localized dissolution would otherwise occur under the film, resulting in pit formation during the LPD treatment. During re-anodizing, these pits act as a mold for anodic oxide resembling a nano-dot like structure. Optimization of LPD parameters, such as time and temperature, would make it possible to obtain alumina films with nano-dot structures with sizes smaller than 1 µm. Alumina films with nano-dot structures with hollow can be realized by controlling the LPD conditions. Copyright © 2013 John Wiley & Sons, Ltd.