Dual-Gate Modulation in a Quantum Dots/MoS<sub>2</sub> Thin-Film Transistor Gas Sensor
Yanting Tang, Bowen Zhou, Jing‐yao Liu, Xinyi Chen, Haizhen Wang, Zhixiang Hu, Rongyu Mao, Yingying Xing, Hua‐Yao Li, Dehui Li, Huan Liu
Abstract
Mastering the surface chemistry of quantum dots (QDs) has enabled a remarkable gas-sensing response as well as impressive air stability. To overcome the intrinsic receptor-transducer mismatch of QDs, PbS QDs used as sensitive NO 2 receptors are spin-coated on top of a few-layer MoS 2 and incorporated into a thin-film transistor (TFT) gas sensor. This architecture enables the separation of the electron transduction function from the chemical reception function. A comparison study through size engineering of QDs combined with TFT device modeling suggests a unique dual-gate modulation related to the capacitance coupling effect of QDs. The favorable increase in sensor output current by 3 orders of magnitude is ascribed to the high mobility of the few-layer MoS 2 . The optimal sensor exhibits a sensitive (LOD ∼ 0.6 ppb), selective, and recoverable response at room temperature. Because of the dual-gate modulation, the sensor performance is further optimized by varying the gate voltage (a two-fold increase in response to 1 ppm of NO 2 ).