B, C and N adatoms effects on the transport properties in zigzag graphene nanoribbons

The effects of B, C and N adatoms on the electronic structures and transport properties of H-passivated zigzag graphene nanoribbons are investigated by first principles calculations. It is found that the adsorption of a single B, N or C atom can induce a net magnetic moment of 1, 1 or 2 mu(B), respectively. All such adatoms can induce both acceptor-like and donor-like quasilocalized states which backscatter the electrons and thus block the transmission. This is reflected in the transmission function by a transmission dip both above and below the Fermi level, which is completely different from the cases with B or N substitution where only one valley appears either above or below the Fermi level. Especially, we find that a single adatoin can even break the edge states, and consequently completely suppress the transmission channel contributed by the related edge states. Meanwhile, the transmission is highly spin polarized, but the spin polarization in current at low bias is negligible in all the B. N and C adsorption cases. (c) 2012 Elsevier Ltd. All rights reserved.