Self-assembled porous tantalum oxide prepared in H2SO4/HF electrolytes

Abstract

The formation of porous Ta2O5 on tantalum was investigated in H2SO4 electrolytes containing low concentrations of HF (0.15 wt %). Under optimized electrochemical conditions, porous Ta2O5 consisting of self-assembled pore arrays with single pore diameters of ~20 nm and a pore spacing of ~15 nm forms. The pore structure and the pore distribution depend on the concentration of HF, the anodization voltage, and the time for anodic oxidation. Porous layers ~400 nm thick with a regular pore distribution can be formed. For thicker layers cracking and a tendency for delamination was observed.