Amplified Methanol Sensitivity in Reduced Graphene Oxide FET Using Appropriate Gate Electrostatic

The current study concerns a technique to amplify the gas sensitivity of reduced graphene oxide (rGO)-field-effect transistor (FET) sensor for the detection of very low concentration gaseous species. rGO channel exhibits tunable carrier density with ambipolar transport in FET structure by the change of electrostatic potential through the gate terminal. At low carrier density of channel, the exchange of carriers due to surface adsorption and desorption is significant that eventually enhances the sensitivity of the rGO-FET sensor at a typical gate voltage (VGS). The back-gated rGO-FET sensor was fabricated on p-Si substrate with 90-nm-thick SiO2 layer. The defects, disorders, and morphology of single-layer (major) rGO were characterized with the spectroscopic and microscopic study. The modulation of ambient sensitivity of rGO film was tested in the exposure of different ambient like dry air, argon, oxygen, and a test vapor methanol. 1.95% methanol (at 150 ppm) sensitivity at VGS = 0 V was amplified up to 127.93% at VGS = 5 V and 82.38% at VGS = 13 V where the temperature and drain-to-source voltage (VDS) were 100 °C and 1.4 mV, respectively.