p-TiO2/GO heterojunction based VOC sensors: A new approach to amplify sensitivity in FET structure at optimized gate voltage

Abstract

Graphene/graphene oxide (GO) field effect transistor (FET) is widely investigated for the mainstream electronics. On the other hand, GO and TiO2 nanocomposite is extensively reported for sensing and energy applications. In the current study, we developed p-type TiO2/GO hybrid channel based back gated FET sensors for the detection of volatile organic compounds (VOCs) of very low concentrations. High sensitivity at low concentration of VOC was achieved by high surface reactivity towards VOC by p-TiO2/GO heterojunctions and limited drain current at appropriate gate voltage near Dirac point. Ambipolar transport due to field effect is only observed in GO dominated nanocomposites where 1 vol% p-TiO2 and 99 vol% GO based FET exhibits best performance having 115% response in 100 ppm ethanol at 100 °C with VDS = 0.5 V, VGS = 0.7 V. The response is enlarged ~ 34 times at VGS = 0.7 V as compared to the VGS = 0 V extending the lower detection limit of ethanol up to 500 ppb.