Enhanced sensitivity of graphene gas sensors using molecular doping

The sensitivity of a graphene gas sensor to a gas analyte molecule may be significantly enhanced using molecular doping, which may be as effective as substitutional doping and more effective than electric-field doping. In particular, the room temperature sensitivity of NO2-doped graphene to NH3 was measured to be comparable to the sensitivity of graphene doped with substitutional boron atoms and superior to that of undoped graphene by an order of magnitude. The detection limit for NO2-doped graphene gas sensors was estimated to be about 200 ppb, which may be improved with extended exposure to NO2, compared to a detection limit of about 1.4 ppm for undoped graphene. While the stability analysis of NO2-doped graphene sensors indicates that the doping method may not be completely stable, molecular doping is nevertheless a candidate technique for sensitivity improvement by enhancing the initial carrier concentration.