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

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.