▎ 摘　　要

The electronic and phase-coherent transport properties of a doped zigzag graphene nanoribbon are studied theoretically in this paper. The I-V curve of the device shows an interesting negative differential resistance (NDR) phenomenon. We found that the NDR is caused by the chiral tunneling of graphene, which is attributed to the symmetry of the eigenstates of individual subbands. This new physics finding is helpful for us to gain more insights about carrier transport in graphene nanoribbons and to design graphene-based nanoelectronic devices. (C) 2008 American Institute of Physics.