High throughput fabrication of ordered nanostructures of semiconductors is an important subject for the preparation of the photo-energy devices with high conversion efficiencies¹. Anodization process of metal is a promising candidate for the efficient fabrication of nanostructured semiconductors with controlled geometrical structures². Anodic porous alumina, which is formed by anodization of Al in acidic solution, is a typical self-ordered material. The use of the anodic porous alumina as a starting structure allows the efficient preparation of the semiconductors with controlled geometrical structures, such as nanorods or nanodots arrays³. The anodization processes of appropriate metals can also generates the semiconductors with controlled geometrical structures. For example, the anodization of Ti in the electrolyte containing F^- generates the porous TiO₂ with controlled nanostructures⁴. In the present report, recent results concerning the fabrication processes for the semiconductors with ordered geometrical nanostructures for the photo-energy conversion will be described. The processes include the preparation of semiconductor nanorod arrays from anodic porous alumina templates and its application to organic photovoltaic solar cells. In addition, anodization process using pretextured Ti for the TiO₂ with ideally ordered hole arrangement will be shown⁵. This process can be also applied to the fabrication of porous TiO₂ with modified hole shapes⁶. The results of the efficient fabrication of ordered TiO₂ will be also described. The obtained semiconductor nanostructures will be applied to various types of photo-energy conversion devices with high efficiency originated from precisely controlled geometrical structures.

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