Transmission spectra of the ultrarelativistic quasielectrons in the single barrier structures based on the gapped graphene

Abstract

Contact structures composed of three regions of graphene are considered, the middle of which is the potential barrier for the quasielectrons. Within the framework of the continuum model, based on the Dirac-type equation, the transmission coefficient T of quasielectrons is calculated and analyzed: In one of them the barrier region (which is believed to be of a rectangular shape) is represented by the gapped graphene and out-of-barrier regions—by the gapless one (structure “b”), in another structure on the contrary, the barrier region is a massless graphene, out-ofbarrier regions—massive graphene (structure “a”). It is believed that there is an electrostatic barrier, as well as the Fermi velocity barrier due to the fact that this quantity may acquire different values in the barrier and out-of-barrier regions (υ F2 and υ F1, respectively) of the considered structure. The presence of an energy gap can lead to significant reduction of T. This fact can be used in the development of transistor-type devices based on graphene. The transmission coefficient T is very sensitive to the parameter ɛ = υ F2/υ F1. The resonances of the Fabry-Perot type as well as the presence of a critical angle of incidence of quasielectrons on the barrier play an important role in the formation of the transmission spectra. The analysis of the coefficient T dependence on the quasielectron energy and other (except for ɛ) problem parameters, such as the energy gap, the barrier width, is also provided.