Fabrication of thin film titania with nanopores, nanopoles, and nanopipes by nanoporous alumina template

We demonstrate the formation of thin film titania (TiO ₂) with a dense array of nanopores, nanopoles, and nanopipes. The heights of pores, poles, and pipes were approximately 130 nm, 180 nm, and 200 nm, respectively. The aspect ratios of these three structures were approximated between 2 and 3. In order to obtain titania thin films, a nanoporous alumina (Al ₂O ₃) template was fabricated by performing a two-step anodization process. The spin-coated titania films were uniformly patterned by a nanoimprinting lithography technique with a textured poly(methyl methacrylate) (PMMA) mold or nanoporous alumina template. The titania films are very useful for solar cells, photocatalytic and sensing applications, in which nano-structuring of surfaces with controlled dimensions is vital.