▎ 摘　　要

In this paper, graphene/mica and graphene/SiO2 based ammonia gas sensors are compared. It is found that adsorbed NH3 molecules result in up-shifting of the Fermi level in graphene, leading to a significant increase in graphene resistance. In comparison with SiO2 supporting substrate, the mica supporting substrate is found to induce more p-doping in graphene, in favour of NH3 molecule adsorption, yielding a high sensitivity. These findings suggest that the substrate plays an important role in mediating the interaction between graphene and NH3 molecules and that mica can be an excellent underlying substrate for graphene for ammonia gas detection. (C) 2014 AIP Publishing LLC.