Electron transport through a graphene quantum dot: the role of line defect

Abstract

We investigate the electron transport through a graphene quantum dot with one line defect, by coupling the dot to two normal metallic leads. It is found that in the cases of the leads coupling to the same-type edges of the dot, the presence of line defect enhances the conductance at the Dirac point by inducing a new conductance peak or strengthening the original conductance peak. Such results are irrelevant to the graphene dot size. On the other hand, if the leads couple to the different-type edges of the dot, the line defect will induce two new conductance peaks near the Dirac point. The conductance enhancement is considered to originate from the fact that one bound state at the Dirac point induced by the line defect couples to the leads, which provides an additional channel for electron motion. Nevertheless, different dot–lead coupling manners change the contribution of the new channel to the electron motion, leading to the complicated transport results. These results show that the line-defect-existed graphene quantum dot will be beneficial to the realization of electron transport manipulation.