Negative capacitance switching via VO₂ band gap engineering driven by electric field

We report the negative capacitance behavior of an energy band gap modulation quantum well with a sandwich VO₂ layer structure. The phase transition is probed by measuring its capacitance. With the help of theoretical calculations, it shows that the negative capacitance changes of the quantum well device come from VO₂ band gap by continuously tuning the temperature or voltage. Experiments reveal that as the current remains small enough, joule heating can be ignored, and the insulator-metal transition of VO₂ can be induced by the electric field. Our results open up possibilities for functional devices with phase transitions induced by external electric fields other than the heating or electricity-heat transition.