Gate-field-induced phase transitions in VO₂: monoclinic metal phase separation and switchable infrared reflections

In a metal-oxide-semiconductor VO₂ active layer under uniaxial stress, gate-field-induced phase transitions are revealed by strongly field-dependent Raman scattering and infrared reflections. A metal-insulator transition (MIT) is demonstrated by a strongly correlated monoclinic metal phase separation that percolates, thereby making the reflections switchable. In addition, the MIT occurs at a gate voltage around 3.36 V, much lower than the threshold of a structural phase transition (SPT). Hence, the MIT is easily controlled by the gate field to avoid the SPT-caused fatigue and breakdown in high-speed operation.