Asymmetric lateral graphene/h-BCN heterojunctions: A new method for separation of carriers in graphene nanoribbon photodetectors

Abstract

Separation of photo-excited carriers (electrons and holes) is one of the most basic mechanisms needed in any photodetector and implies the efficiency of the photodetector. Applying electric field in the longitudinal direction of the photodetector channel is the traditional way to this end. The necessary electric field can be applied externally by a voltage bias or internally by a p-n junction, a Schottky barrier, etc. However, recently it is shown that any factor that causes any asymmetry in the channel of the photodetector can induce carrier separation. Asymmetric potential barriers can be used to this end. In this paper, a new method will be introduced. Recently, new 2D hybrid structures of carbon and boron-nitride, h-BCN, have been introduced. Different mole fractions of carbon, boron, and nitrogen atoms in these structures can lead to different band-gaps and electron affinities. This property can be used to construct different heterostructures. In this work, we use these heterostructures to produce asymmetric potential barriers for separation of photo-excited carriers. The structures are computed with a TB model and NEGF formalism in this paper and the results show that they can produce carrier separation.