Millimeter-wave to near-terahertz sensors based on reversible insulator-to-metal transition in VO₂

In the quest for low power bio-inspired spiking sensors, functional oxides like vanadium dioxide are expected to enable future energy efficient sensing. Here, we report uncooled millimeter-wave spiking detectors based on the sensitivity of insulator-to-metal transition threshold voltage to the incident wave. The detection concept is demonstrated through actuation of biased VO₂ switches encapsulated in a pair of coupled antennas by interrupting coplanar waveguides for broadband measurements, on silicon substrates. Ultimately, we propose an electromagnetic-wave-sensitive voltage-controlled spike generator based on VO₂ switches in an astable spiking circuit. The fabricated sensors show responsivities of around 66.3 MHz.W^-1 at 1 μW, with a low noise equivalent power of 5 nW.Hz^-0.5 at room temperature, for a footprint of 2.5 × 10^-5 mm². The responsivity in static characterizations is 76 kV.W^-1. Based on experimental statistical data measured on robust fabricated devices, we discuss stochastic behavior and noise limits of VO₂ -based spiking sensors applicable for wave power sensing in mm-wave and sub-terahertz range.