▎ 摘　　要

We study the transport property for armchair-edge graphene nanoribbons (AGNRs) with an adatom coupling to a semi-infinite quantum wire. Using the nonequilibrium Green's function (NEGF) approach with tight-binding approximation, we demonstrate that the tunneling current through the system is sensitively dependent on both the AGNR width and adatom location. Interestingly, when the adatom locates onto a carbon atom in the 3jth chain from the edge of a metallic AGNR, the system shows a transmission gap accompanied by a threshold voltage like a semiconducting AGNR. This effect may be useful in scanning tunneling microscopy experimental characterization on graphene samples. (C) 2011 American Institute of Physics. [doi:10.1063/1.3555445]