Enhancing electrical properties of BiFeO3-based thin films via introducing VO2 overlayers with double-interface charge barrier

Abstract

Developing high-performance lead-free ferroelectric materials is a significant challenge for flexible electronics and high-temperature memory applications. However, the high leakage current and poor electrical stability of BiFeO3-based films severely restrict their practical use. Here, we propose an interface engineering strategy that integrates a vanadium dioxide (VO2) overlayer onto 0.7BiFeO3–0.3BaTiO3 ferroelectric films using pulsed laser deposition, constructing a double-interface charge barrier. We systematically investigate the effects of the VO2 overlayer on the crystal structure, ferroelectric properties, and interface energy band alignment of the thin films. A 20 nm-thick VO2 overlayer reduces leakage current by one order of magnitude, enhances breakdown field strength to 6.6 MV/cm at 300 K and remains 5.3 MV/cm with high endurance of 108 cycles at a high temperature of 500 K. These improvements are attributed to the synergistic suppression of carrier migration by the double-interface charge barrier and the optimization of band alignment at high temperatures by the metal–insulator transition of VO2, which reduces interface defect density. This work opens new avenues for developing high-temperature stable ferroelectric memories and inspires new paradigms for functional oxide integration in extreme-condition electronics.