Double Quantum Dot Field Effect Transistor on Graphene

A novel functional field effect transistor (FET) is introduced. The proposed FET is modeled on graphene nanoribbon (GNR), however it is applicable for any two-dimensional (2D) structures with energy gap. As in most graphene-based FETs, current passes through semiconducting 2D GNR. But here by the special geometry of gate contact, the GNR is turned into two coupled quantum dots in series. By applying gate voltage, discrete energy levels are generated in the two quantum dots of the channel and resonant tunneling transport occurs through these levels. The coupling between dots and sizes of dots determine the current characteristic of the device. By self consistently solving the NEGF and 3D Poisson equations, current of the FET is derived. Resonant tunneling of carriers results in a stepwise increase in current with drain voltage and current peaks are observed by the increment of gate voltage; i.e., negative differential conductance occurs.