Capacitive NO(2) Detection Using CVD Graphene-Based Device

A graphene-based capacitive NO(2) sensing device was developed by utilizing the quantum capacitance effect. We have used a graphene field-effect transistor (G-FET) device whose geometrical capacitance is enhanced by incorporating an aluminum back-gate electrode with a naturally oxidized aluminum surface as an insulating layer. When the graphene, the top-side of the device, is exposed to NO(2), the quantum capacitance of graphene and, thus, the measured capacitance of the device, changed in accordance with NO(2) concentrations ranging from 1–100 parts per million (ppm). The operational principle of the proposed system is also explained with the changes in gate voltage-dependent capacitance of the G-FET exposed to various concentrations of NO(2). Further analyses regarding carrier density changes and potential variances under various concentrations of NO(2) are also presented to strengthen the argument. The results demonstrate the feasibility of capacitive NO(2) sensing using graphene and the operational principle of capacitive NO(2) sensing.