Quantum dot resonant tunneling FET on graphene

At this paper a field effect transistor based on graphene nanoribbon (GNR) is modeled. Like in most GNR-FETs the GNR is chosen to be semiconductor with a gap, through which the current passes at on state of the device. The regions at the two ends of GNR are highly n-type doped and play the role of metallic reservoirs so called source and drain contacts. Two dielectric layers are placed on top and bottom of the GNR and a metallic gate is located on its top above the channel region. At this paper it is assumed that the gate length is less than the channel length so that the two ends of the channel region are un-gated. As a result of this geometry, the two un-gated regions of channel act as quantum barriers between channel and the contacts. By applying gate voltage, discrete energy levels are generated in channel and resonant tunneling transport occurs via these levels. By solving the NEGF and 3D Poisson equations self consistently, we have obtained electron density, potential profile and current. The current variations with the gate voltage give rise to negative transconductance.