RF field-induced phase transition in vanadium dioxide: Switching dynamics, power thresholds, and reliability

Abstract

Nonlinear behavior of phase-change materials such as vanadium dioxide (VO2) can be exploited to create novel electromagnetic devices such as low-loss radio frequency (RF) switches. The interaction of the RF or optical wave with such nonlinear media provides unique opportunities to realize new electromagnetic structures such as nonreciprocal devices, routers, and limiters. Yet, the nonlinearity resulting from the insulator-metal transition (IMT) is often only defined for a temperature or dc voltage dependency. We report the first study of RF field-induced transition of VO2. Several coplanar waveguide structures with series nonlinear elements (i.e., switches) are designed, fabricated, and characterized over the RF power range that induces the nonlinearity. The experimental findings of the RF field-induced transition, including how the geometry of the VO2 affects the transition threshold and the power handling, are reported. We demonstrate a 60 ns switching time and the switching speed dependency on input power. We also report high reliability across 10 × 106 cycles of the RF field-induced transition of VO2. These findings establish RF field excitation as a viable and efficient mechanism for triggering the IMT in VO2, offering significant potential for next-generation high-speed, reconfigurable RF and mmWave applications.