Observation of the Pinch-Off Effect during Electrostatically Gating the Metal-Insulator Transition

Electrostatically controlling material phases has been a long-standing challenge. While it is partially achieved by electrostatic gating with ionic liquid, it often involves unintended chemical reactions. In this sense, it has recently attracted tremendous attention that a solid-state electrostatic gating is successfully applied to insulator-metal transition by using ultrahigh-permittivity gate dielectrics. However, the detailed characteristics of this new class of device are totally unknown. Here, systematic studies are performed on the three-terminal device using VO₂ insulator-metal transition and TiO₂ gate dielectrics, and for the first time the pinch-off effect in phase transition devices is observed, a clear sign of electrostatic gating. Furthermore, the increase in the drain voltage has a “catalytic effect” of drastically sharpening the gate-induced transition, demonstrating a 0.1 V gate control. The characteristics are simulated by a quasi-equilibrium model, providing the firm ground for electrical control of material phases with high speed and high resolution.