A novel graphene nanoribbon field effect transistor with two different gate insulators

• A novel structure with two different gate insulators for GNRFET (TDI-GNRFET) is proposed.
• Mode-space Non-Equilibrium Green's Function (NEGF) formalism in the ballistic regime is used.
• TDI-GNRFET has lower leakage current and higher Ion/Ioff ratio in comparison with low-K GNRFET.
• TDI-GNRFET has smaller capacitances and lower intrinsic delay in comparison with high-K GNRFET.
• The proposed TDI-GNRFET has good Drain Induced Barrier Lowering (DIBL) and subthershold swing.

In this paper, a novel structure for a dual-gated graphene nanoribbon field-effect transistor (GNRFET) is offered, which combines the advantages of high and low dielectric constants. In the proposed Two Different Insulators GNRFET (TDI-GNRFET), the gate dielectric at the drain side is a material with low dielectric constant to form smaller capacitances, while in the source side, there is a material with high dielectric constant to improve On-current and reduce the leakage current. Simulations are performed based on self-consistent solutions of the Poisson equation coupled with Non-Equilibrium Green's Function (NEGF) formalism in the ballistic regime. We assume a tight-binding Hamiltonian in the mode space representation. The results demonstrate that TDI-GNRFET has lower Off-current, higher On-current and higher transconductance in comparison with conventional low-K GNRFET. Furthermore, using a top-of-the-barrier two-dimensional circuit model, some important circuit parameters are studied. It is found that TDI-GNRFET has smaller capacitances, lower intrinsic delay time and shorter power delay product (PDP) in comparison with high-K GNRFET. Moreover, mobile charge and average velocity are improved in comparison with low dielectric constant GNRFET. The results show that the TDI-GNRFET can provide Drain Induced Barrier Lowering (DIBL) and Subthreshold Swing near their theoretical limits.