Effect of the anodization voltage on the pore-widening rate of nanoporous anodic alumina
1 Nano-electronic and Photonic Systems (NePhoS), Universitat Rovira i Virgili, Avinguda Paisos Catalans 26, Tarragona, 43007, Spain
2 LPICM, Ecole Polytechnique, CNRS, Palaiseau, 91128, France
Nanoscale Research Letters 2012, 7:474 doi:10.1186/1556-276X-7-474Published: 23 August 2012
A detailed study of the pore-widening rate of nanoporous anodic alumina layers as a function of the anodization voltage was carried out. The study focuses on samples produced under the same electrolyte and concentration but different anodization voltages within the self-ordering regime. By means of ellipsometry-based optical characterization, it is shown that in the pore-widening process, the porosity increases at a faster rate for lower anodization voltages. This opens the possibility of obtaining three-dimensional nanostructured nanoporous anodic alumina with controlled thickness and refractive index of each layer, and with a refractive index difference of up to 0.24 between layers, for samples produced with oxalic acid electrolytes.