Formation of ideally ordered porous Ga oxide by anodization of pretextured Ga

An ideally ordered nanohole array of Ga oxide was formed by anodizing pretextured Ga. Prior to anodization, an ideally ordered array of concaves was formed on the Ga surface by nanoimprinting using a metal mold. The anodization of the pretextured Ga was carried out in a phosphoric acid solution. During anodization, each concave acted as a starting point of hole generation, resulting in the formation of the ideally ordered porous Ga oxide. The present process is expected to be applied to fabricate a light energy conversion device, such as a hydrogen formation device.