Energy selective tunneling in doped graphene ribbons

We present a numerical study of the differential conductance of doped zigzag graphene ribbons with an even or odd number of chains. In the even case, it is shown that a perfect blocking of current flow occurs in bipolar graphene strips, when a single conductive channel is active in both the p-doped and the n-doped regions. It is also discussed how to extend the energy region where the Klein tunneling is forbidden. The occurrences of selective energy ranges, ideally opaque to carrier tunneling, enriches the applicative perspectives of carbon-based nanostructures.