Electrically-Controlled Carrier Guiding in Single-Channel Graphene Device

Abstract

We propose a single-channel graphene device where charge carriers can be guided to a specific direction just by controlling the electrostatic environment in the channel. The almost perfect ballistic propagation of electrons and the angle-dependent electron transmission can be achieved in graphene with well-designed one-dimensional external periodic potentials. We have performed theoretical calculations on the time-evolving probability density of an electron wave packet in graphene superlattice structure, which is a Kronnig-Penny type of periodic potential generated with alternating n- and p-type doping regions in graphene. The alternating n- and p-type doping regions are formed by applying proper voltages on the comb-shape top gate and global bottom gate electrodes. Our calculations show that the propagation direction and spread of electron wave packet in graphene sensitively depend on the magnitude of superlattice potential. The ratio between the number of electrons flowing into the drain electrode and that of electrons flowing into the side drain is found to be modulated arbitrarily by tuning the biases applied to the top and bottom gate electrodes. Our work provides an efficient and scalable method to fabricate graphene field effect transistors with large on-off ratio while maintaining the high carrier mobility of graphene, associated with its zero band gap nature.