Gas-Selective Signal Amplification in Fluctuation-Based Graphene FET Sensors

The power spectrum of conductance fluctuations arising from the adsorption of gas molecules to a graphene field-effect transistor was shown to contain the signature of the adsorbing species recently. A detailed mechanism of the phenomena was not provided although it was remarked that these conductance fluctuations arise due to the number fluctuations of the adsorbed molecules, which may donate (or accept) electrons to (or from) graphene. In this paper, we report on a phenomenological model based on conductance fluctuations and analyze a novel sensing configuration consisting of a sinusoidally varying gate voltage sweeping across the Dirac point, which changes the sign of conductance response to adsorption. We show that this configuration leads to gas-selective amplification of peaks of the conductance fluctuation spectra.