Transport Properties Of Electron In T-Stub P-N Graphene Junctions

In recent years, the advanced nanotechnology makes the condensed matter physics to be a popular research field. Graphene as a single sheets material has generated a great interest in the study of the dynamics of carriers, both from a fundamental standpoint, as well as in view of possible applications. In this dissertation, we have studied the transport properties of the electrons through a single stub (T-stub) graphene P-N junction. Compared to the graphene nanoribbions with normal shapes, the existence of the stub induces quantum interference effects of the electrons during they transport, which have the obvious influences on the conductance. Meanwhile, an external vertical magnetic field can change the quantum interference effect of the electrons with different spin orientations. Furthermore, the electric conductance can also be controlled by magnetic field. Transport properties are quite different between zigzag and armchair edge stub structures because of the different edge shapes.By using Landauer-Buttiker equation combined with lattice Green function method, we study the influence of order and disorder on the conductance of the nano-stub structures with zigzag and armchair edge. We have find:the conductance platform can be obtained by changing the magnetic field and the gate voltage in the N-N region. On the contrary, the conductance decreases with the increase of the applied magnetic field in the P-N region, some new peaks of conductance arise. It can also be found that some conductance platform decrease and disappear due to suppression of the magnetic field on the conductance. The conductance shows some peaks in the P-N region when the disorder strength approach zero, which is attributed to the interference effects of electrons.