Novel Band Structures and Transport Properties from Graphene Nanoribbons with Armchair Edges

Abstract

Using an empirical linear combination of atomic orbitals method (LCAO) based on the sp3 tight-binding scheme, we studied the band structures of graphene nanoribbons with armchair edges terminated by H atoms and found that the band gap exhibits the size dependence and the ‘family’ behaviors, in which a metallic graphene nanoribbon and two semiconducting graphene nanoribbons coexist in a ‘family’. On the basis of Pichard’s transfer matrix technique, we calculated the conductance of the graphene nanoribbons and interestingly found that the steplike curves of conductance display conductance plateaus in the integer multiples of G0 = 2e2/h and the conductance gap emerges in the semiconducting graphene nanoribbon. Meanwhile, a side needle is located on the conductance curve at zero energy in the metallic graphene nanoribbon, which is attributed to degeneration of eigenstates at zero energy. Additionally, we showed that edge states do not have a notable contribution to the conductance because of the strong locali...