In this paper, a new structure for a dual-gated graphene nanoribbon field-effect transistor (GNRFET) is proposed, which each part of the source and drain regions are divided into three sections with different doping concentrations. We use highly doped concentration in the first part of both contacts for achieving ohmic structure. For obtaining the high current ratio and consequently high efficiency, the number and doping concentrations of lightly doped regions are optimized. In order to simulate the device characteristics, the self-consistent solution of Poisson and Schrödinger equations based on the non-equilibrium Green's Function (NEGF) formalism is used in the ballistic regime. To write the Hamiltonian matrix, we use the tight-binding approximation method in the real space, which has high precision. The obtained simulation results show that, the band-to-band tunneling (BTBT) and ambipolar behavior in the proposed double-lightly doped GNRFET (DLD-GNRFET) are significantly reduced and consequently, the OFF current and delay time are decreased, which are significantly observed in the conventional GNRFETs (C-GNRFETs). Furthermore, the proposed structure has larger ON/OFF ratio, lower subthreshold swing and smaller drain induced barrier lowering (DIBL), in comparison with the C-GNRFETs.
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