Study of the Filtering and Noise Properties of a Series of Tunnel Barriers in a Graphene Ribbon

Using our envelope-function based simulator, we study the transport and noise properties of a graphene ribbon with a series of unevenly spaced parallel potential barriers, as a function of the number of cascaded barriers. In our calculations, performed assuming various potential profiles, we consider barriers both with identical and with different width. In particular, exploiting Klein tunneling, we propose to use this device as a mode filter, allowing the propagation of just a small number of modes along the ribbon. Then, we examine the onset of localization as the number of barriers is further increased. Finally, we analyze how the conductance and noise behavior is affected by the inclination of the barriers with respect to the nanoribbon axis. In order to gain a more complete understanding of the observed phenomena and for comparison purposes, a few analogous calculations are performed also for GaAs quantum wires