Transition in Electronic Transport Properties of Graphene Nanoribbon Due to the Adsorption of Atoms and Molecules

The adsorption effects of gas molecules on semiconducting armchair graphene nanoribbon (A-GNR) are studied considering on the significant changes over current-voltage characteristics, device density of states and electrostatic difference potential. The orientation of gas molecules and adsorption sites play an important role on charge transfer between the graphene surface and the molecules. The charge transfer mechanism is discussed in the light of molecular orbital theory. We have used three gas molecules - CO2, NH3 and NO as adsorbates and chose such orientation that adsorbates can act only as donor. Finally, we have made a conclusion that semiconducting A-GNR shows metallic behaviour after adsorbing optimum number of adsorbates corresponding to the area of A-GNR. Such semiconducting to metal transition can be used as sensing parameters.