Gate-Modulated Temperature-Dependent\nNO<sub>2</sub> Gas Responsivity of h‑BN Bottom-Gated MoS<sub>2</sub> Field-Effect\nTransistor

Although many studies have explored 2D material-based\nfield-effect\ntransistor (FET)-type gas sensors to overcome relatively low gas responsivity,\nthe role of gate bias remains unclear and understudied. In this work,\nthe influence of gate-modulated channel states and thermally excited\ncarriers on the responsivity of MoS<sub>2</sub>/h-BN FETs to NO<sub>2</sub> gas is systematically investigated and a detailed mechanism\nis proposed. The electrical state of the channel is defined through\nelectrical parameters such as threshold voltage, carrier density,\nand interface trap density, and the corresponding gas responsivity\nis evaluated using time-domain gas measurements. When the device operates\nin the subthreshold region, partial channel depletion leads to a weak\nconduction channel at the surface, where the gas reaction primarily\noccurs. With increasing temperature, thermally excited carriers further\ncontribute to the gas reaction, resulting in a significant increase\nin responsivity, up to 2922%, without the need for surface functionalization.\nThis study provides valuable insights into the gas sensing mechanisms\nof transition metal dichalcogenides-based FETs and proposes effective\nstrategies for enhancing gas response under various conditions.