Electrostatic and substrate-based monolayer graphene superlattices: Energy minibands and its relation with the characteristics of the conductance curves

Abstract

We study the transmission, transport and electronic structure properties of monolayer Graphene Superlattices (GSLs). The transfer matrix method has been implemented to obtain the transmittance, linear-regime conductance and electronic structure. In particular, we have studied two types of GSLs: (1) Electrostatic GSLs (EGSLs), structures formed with electrostatic potentials and (2) Substrate GSLs (SGSLs), obtained by alternating substrates that can open and non-open, such as SiC and SiO2, an energy bandgap on graphene. We have found that the transmission properties can be modulated readily by changing the main parameters of the systems: well and barrier widths, energy and angle of the incident electrons and the number of periods of GSLs. In the case of the linear-regime conductance turns out that it diminishes by increasing the barrier width as well as the number of periods for SGSLs. On the contrary, Klein tunneling sustains the conductance in EGSLs. Calculating the electronic structure or miniband-structure formation we establish a direct connection between the conductance peaks and the start–end and degeneration (narrowing) of the energy minibands for EGSLs, and start–end, degeneration (narrowing) and closure in the case of SGSLs.