Effect of molybdenum disulfide nanoribbon on quantum transport of graphene

Based on the density functional theory method in combination with the nonequilibrium green's function formalism, the quantum transport properties in graphene–${MoS}_2$ vertical heterojunction were investigated in this work. The leads are boron doped graphene and seamlessly connect to the graphene nanoribbon in central scattering region. Although there is a weak graphene–${MoS}_2$ interaction, molybdenum disulfide can smooth the electrostatic potential and enlarge the transport properties of the whole device. However, another competitive factor is that of the edge states of the ${MoS}_2$ nanoribbon. When the transport is along the zigzag direction of graphene, the armchair ${MoS}_2$ nanoribbon simply enlarges the transmission coefficient. Nevertheless, in the armchair transport system, there is an asymmetric electrostatic potential induced by the different atomic potentials of S and Mo atoms at both edges in the zigzag ${MoS}_2$ nanoribbon, whose potential can lead to obvious scattering from graphene to ${MoS}_2$ and suppress the transmission probability. Therefore, it also suppresses the influence of zigzag ${MoS}_2$ nanoribbon on the transmission coefficient. Our first principles simulations provide useful predictions for the application of graphene based emerging electronics, which may stimulate further experimental exploration. (paper)