Resonant transport and quantum bound states in Z-shaped graphene nanoribbons

We study the transport properties of a Z-shaped graphene nanoribbon (GNR). It is found that the quasibound states in the Z-shaped junction induce resonant peaks around the Dirac point in the conductance profile. The resonant transmission via the quantum bound state is very sensitive to the size of the junction. The number and also the lifetimes of the quasibound states increase with the size of the Z-shaped junction. Long lifetime bound states which do not induce obvious resonant peaks exist in the junction with a wider or longer zigzag edged GNR. The resonant characteristics of the Z-shaped GNR can be tuned by the variation of the geometrical size.