Effect of surface plasmons at the Al/alumina interface on the formation of nanopores in Al anodization

Abstract

We investigated the formation mechanism of nanoporous alumina in the electrochemical reaction of aluminium with oxalic acid solution in terms of the pinning effect of Fermi level at the metal–oxide interface. On the Al metal surface, the image potential state pins the standing mode of collectively excited surface electrons and the evanescent wave forms the plasmon mode, which can be reflected in oxide barrier formation. A nanoporous alumina thin film with an amorphous phase oxide layer on the Al surface can enhance light absorption at a shorter wavelength than 382 nm and provide strong Fabry–Perot oscillation in photoreflectance. The cathodoluminescence spectra show the surface plasmon mode as a consequence of the self-ordered oxide nanopores. The Kretschmann configuration of an attenuated total reflection set-up for prism/oxalic solution/Al interface, which also provides a prism-coupled surface plasmon and forms oxide nanopores on the Al surface via a laser-enhanced anodization process.

Keywords:

• anodized aluminium oxide
• hexagonal nanopores
• image potential state
• surface plasmon

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Small and Medium Business Technology Development Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant, funded by the Korean government [grant number SMTECH-S216338]; research funds of Chonbuk National University in 2013 [grant number CBNU-2013].