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Simultaneous Achievement of Superior Response and Full Recovery of Titanium Dioxide/Graphene Hybrid FET Sensor for NH3 through p- to n- Mode Switch

Abstract

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 NH3 are achieved through sensing mode switch via gate biasing. -16.40% response and full recovery for 25 ppm NH3 are achieved for TiO2/GFET sensor with 100% titanium dioxide coverage (D100) at RT (27℃) with 15%-20% humidity upon switching sensing mode from p- to n- via gate biasing. Full recovery is attributed to the Coulomb interaction between charged polar donor molecules and positively polarized surface enhanced by the switch from p- to n- mode. The humidity can enhance response up to -35.48% for 25 ppm NH3 with full recovery in n- mode for D100. The sensing behaviors for NH3 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 via incorporating proper electron (hole) rich materials to compensate holes (electrons) in p (n)- type materials for electron donor (acceptor) gases detection.

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Supplementary files

Article information


Submitted
17 Apr 2020
Accepted
10 Jun 2020
First published
30 Jun 2020

Phys. Chem. Chem. Phys., 2020, Accepted Manuscript
Article type
Paper

Simultaneous Achievement of Superior Response and Full Recovery of Titanium Dioxide/Graphene Hybrid FET Sensor for NH3 through p- to n- Mode Switch

A. Falak, Y. Tian, L. Yan, X. Zhang, L. Xu, Z. Song, F. Dong, P. Chen, M. Zhao, H. wang and W. Chu, Phys. Chem. Chem. Phys., 2020, Accepted Manuscript , DOI: 10.1039/D0CP02070B

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