Fabrication of porous anodic alumina (PAA) templates with straight pores and with hierarchical structures through exponential voltage decrease technique

TL;DR

This paper introduces a novel exponential voltage decrease technique to fabricate porous anodic alumina templates with straight and hierarchical pores, enabling precise control over pore structure for advanced device applications.

Contribution

The study presents a new method combining exponential voltage decay with chemical etching to produce customizable PAA templates with straight and hierarchical pores, advancing fabrication capabilities.

Findings

Straight pores can be achieved despite exponential voltage decay.

Hierarchical nanoporous structures with 2 to 10 branches can be fabricated.

The process allows for precise tuning of PAA structures.

Abstract

The oxide barrier layer at the bottom of the pores has been successfully thinned by applying an exponential voltage decrease process followed by a wet chemical etching. The impact of the potential drop on the porous anodic alumina (PAA) structure has been deeply investigated, as well as the electrolyte temperature, the number of potential steps and the exponential decay rate. The results presented herein evidence that straight pores can be obtained and simultaneously remove the dielectric layer in spite of applying the exponential voltage decay during the PAA synthesis, through a smart adjustment between the anodization conditions and exponential voltage decay parameters. Additionally, the PAA structure can be tuned to fabricate hierarchically nanoporous templates with secondary pores ranging from 2 up to 10 branches. The presented simple procedure aims to become a standard step for the fabrication of the next generation PAA templates based devices.