Enhanced energy storage properties of amorphous BiFeO₃/Al₂O₃ multilayers

Abstract

The energy storage density of ferroelectric thin film capacitors is mainly limited by the breakdown strength. Here we demonstrate that the high breakdown strength and high energy storage density can be achieved by constructing BiFeO₃/Al₂O₃ ferroelectricity-insulators heterojunction. The breakdown strength, leakage current density and energy storage performance are investigated systematically of the multilayer thin films. The relatively high breakdown strength is achieved in the Al₂O₃/BiFeO₃/Al₂O₃/BiFeO₃ thin film, which is benefited from the amorphous structure, built-in electric field and boundary conditions of electromagnetic field. At the same time, the excellent energy storage density of the thin film is obtained mainly due to the effect of high breakdown strength. The proposed structure of this work provides an useful method to improve the energy storage density of thin film capacitors.