In Situ Electrochemical Thinning of Barrier Oxide Layer of Porous Anodic Alumina Template

Abstract

We present three different in-situ post anodization electrochemical techniques to thin down the barrier oxide layers. These techniques include exponential voltage decay, exponential voltage decay with steps and exponential current decay. Faster rate of voltage drops in case of exponential voltage decay results in pore bottom without any modification, where as exponential voltage decay with steps modifies the pore bottom with formation of irregular pore branches. However, exponential current with critical decay constant reduces the oxide barrier layer thickness effectively with formation of narrow open channels along the radial directions of hemispherical pore bottom. The samples prepared under exponential current decay was subjected in KCl solution for a very short span of time to widen channels diameter using cathodic polarization and the resulting structure (porous alumina with open pores) remains on the aluminum substrate. The resulting AAO membrane along with aluminum substrate was used to grow silver nano-wires.