Dual interfacial modification via anodizing method for achieving enhanced breakdown strength in multi-layer anodized alumina/Sr0.85Bi0.1TiO3 films

Abstract

Prepared with two layers of anodized alumina (Al2O3), a novel structure of multi-layer anodized alumina/Sr0.85Bi0.1TiO3 (AO/SBT) dielectric capacitor has been designed and fabricated to realize significant improvement in energy density. The first Al2O3 layer (AO1) was artificially introduced through anodic oxidation of aluminum layer in electrolyte, while the second Al2O3 layer (AO2) was automatically generated during the I–V testing process. With ultrahigh breakdown strength, the embedded Al2O3 layers could be taken as the patch to repair the micro-holes located at the interface. In addition, they could be used as barrier layers to dramatically reduce the leakage current. More importantly, it was found that the different location of the AO1 layer has enormous impact on the ultimate breakdown strength. Based on finite element analysis, the simulation results showed the electric field was mainly concentrated on the Al2O3 layer, which could effectively reduce the breakdown probability of SBT films. By dual interfacial modification, the multi-layer thin films with an optimal structure show a remarkable enhancement in breakdown strength from 134.09 to 534.72 MV m−1. As a result, the maximum energy density of 29.71 J cm−3 has been achieved, which represents a ∼741% increase in comparison to the samples without dual interfacial modification. The unique dual interfacial modification technology employed in this work offers a new approach to increase the energy storage density of dielectric capacitors from the perspective of structural design.