Resonant tunneling effect in graphene superlattice heterostructures by tuning the electric potential of defect layer.

In this paper, we have demonstrated the electronic resonant tunneling effect in graphene superlattice heterostructures with an electric potential controlled defect layer. This layer is created by a single irregular electrode inserted in between two different superlattices. We have numerically investigated the tunable giant thermoelectric effect in the above-mentioned structure which is caused by complete electronic tunneling using a transfer matrix approach. The magnitude of the maximum Seebeck coefficient generated in the above structures is several times more than that in an individual superlattice as well as in superlattice heterostructures. This structure can be tuned to give a maximum Seebeck coefficient by varying the applied voltage on the defect layer. By this method, the magnitude of the Seebeck coefficient is found to be 384.9 mV/K, which is the largest reported ever. The tunneling state and the maximum value of the Seebeck coefficient are found to be located in the small overlapped forbidden gap of two graphene superlattices. This voltage controlled tuning technique for complete electronic tunneling is practically preferable against the width controlled technique reported in the literature. These types of structures are important for graphene-based devices which can be used for efficient thermoelectric devices in energy harvesting and high-Q narrowband electron wave filters. [ABSTRACT FROM AUTHOR]