▎ 摘　　要

The switch in the sensing mode for better identification of donor/acceptor gases with simultaneous enhancement of the sensing performance at a fixed working temperature particularly room temperature (RT) is quite challenging for gas sensors. Herein, TiO2/graphene hybrid field effect transistor (FET) sensors (TiO2/GFET) with varied hybrid areas are presented. Superior sensing and recovery performances for NH(3)are achieved through sensing mode switchviagate biasing. 16.40% response and full recovery for 25 ppm NH(3)are achieved for TiO2/GFET sensors with 100% titanium dioxide coverage (D-100) at RT (27 degrees C) with 15-20% humidity upon switching sensing mode from p- to nviagate biasing. Full recovery is attributed to the Coulomb interaction between charged polar donor molecules and positively polarized surface which is enhanced by the switch from p- to n-mode. The humidity can enhance response up to -35.48% for 25 ppm NH(3)with full recovery in n-mode forD(100).D(100)shows superior selectivity towards NH(3)against both electron-acceptor NO(2)and several other electron-donor analytes. The sensing behaviors for NH(3)are well elucidated using energy band diagrams based on the experimental results. This study proposes a novel idea for performance improvement of FET based sensors with p- and n-type hybrid sensing materials through p (n)- to n (p)-mode switch assisted by gate biasing by incorporating suitable electron (hole) rich materials to compensate holes (electrons) in p (n)-type materials for electron donor (acceptor) gas detection.