Self-assembly of stepped hollow oxide nanostructures with plasmonic-photonic properties

We report the formation of hollow oxide nanostructures by oxidation of aluminum nanodots on gold thin film. The nanodots are formed by rapid thermal annealing of the thin film close to its melting point. The heights of the dots can be easily controlled via the initial thickness and temperature. The structure exhibits a phase transition when electrochemically oxidized and forms porous structure with a stepped interior. Despite the high level of disorder, a correlation length can be easily identified from the Fourier transformation of the surface. UV-visible spectroscopy and Fourier transform infrared spectroscopy show a stop gap at 1800 cm(-1) showing the potential for photonic material application despite the high level of disorder.