Strong negative differential conductance in strained graphene devices

In this work, we investigate the transport properties of devices made of graphene strained heterochannels. Due to the effects of local strain on the band structure, the Klein tunneling is strongly suppressed and transport gaps can appear in the unstrained/strained graphene junctions. The gap regions can be modulated in k-space and in energy by strain and doping engineering, respectively. We show that these effects can be exploited to achieve a strong negative differential conductance (NDC) in single gate-induced barrier structures and in p–n junctions. When the local strain is suitably applied, the peak-to-valley ratio (PVR) of the current-voltage characteristics can be as high as a few hundred. The dependence of NDC effect on structure parameters is investigated systematically. In particular, a strong NDC is obtained in single barrier structures with large strained region, while the PVR is not strongly sensitive to the transition length in p–n junctions.