Graphene-gate transistors for gas sensing and threshold control

Graphene has been employed as gate electrodes of n-channel silicon transistors. When the graphene gate is exposed and gas molecules adsorb on the graphene surface, the work function of graphene changes depending on the gas species and concentrations, thus changing the threshold of the silicon transistor. This novel graphene-gate sensor exhibits sensitivities more than one order of magnitude higher than those of the conventional resistivity-based graphene gas sensors, easily detecting 7 ppb of NO
₂
. The selectivity of several gases also exist. Furthermore, the work function of graphene-gate can be controlled by intentionally depositing proper doping materials on graphene, changing the threshold by up to 620 mV without degrading the subthreshold properties.