A carbon-based FET NO2 sensor modulated by the interfacial electric double layer of ionogel sensing dielectric

A side gate FET gas sensor based on ionogel sensing dielectric was designed. • The FET sensor exhibited good NO 2 sensing performance at low side-gate bias of −1 V. • Gas sensing mechanism of gas-induced electric double layer variation was proposed. Field-effect transistors (FETs) have attracted considerable attention in gas detection due to their inherent signal amplification capability. Most of these sensors, whether based on a sensing channel or a sensing gate, still suffer from limited stability and excessive gate voltage, which is detrimental to low-power detection. Herein, a side-gate carbon-based FET (S-FET) gas sensor based on an ionogel sensing dielectric layer is rationally designed. By designing a side-gate structure with the ionogel covering the channel, the channel is isolated from the ambient environment and the ionogel sensing dielectric is fully exposed, which benefits the electrical and sensing stability of the sensor. Besides, the electric double layer (EDL) formed within the ionogel under a low applied voltage serves as an additional electric potential across the side gate and channel, resulting in effective control of the channel conductivity and significantly reducing the gate voltage of the sensor. The fabricated sensor exhibits a response of approximately 182% toward 10 ppm of NO 2 and demonstrates reliable gas-sensing performance over the 0.15–10 ppm range under a low side gate voltage of −1 V. Finally, a gas-sensing mechanism based on gas-induced EDL modulation is proposed. This work proposes a new strategy for fabricating high-performance FET gas sensors based on ionogel sensing dielectrics, providing a reference for designing low-voltage sensing electronics. Download: Download high-res image (181KB) Download: Download full-size image