Effect of the anodization voltage on the porewidening rate of nanoporous anodic alumina

TL;DR

This study investigates how varying anodization voltage affects the pore-widening rate of nanoporous anodic alumina, revealing that lower voltages lead to faster porosity increase, enabling controlled nanostructure fabrication.

Contribution

It provides new insights into the relationship between anodization voltage and pore-widening rate, facilitating precise control over nanostructure properties.

Findings

Lower anodization voltages increase pore-widening rate.

Controlled multilayer nanostructures with specific refractive indices are achievable.

Refractive index difference up to 0.24 between layers.

Abstract

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 porewidening 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.