A Computational Study on the Performance of Graphene Nanoribbon Field Effect Transistor

Despite the simplicity of the hexagonal graphene structure formed by carbon atoms, the electronic behavior shows fascinating properties, giving high expectation for the possible applications of graphene in the field. The Graphene Nano-Ribbon Field Effect Transistor (GNRFET) is an emerging technology that received much attention in recent years. In this paper, we investigate the device performance of Graphene Nanoribbon Field Effect Transistor (GNRFET) as a function of contact doping concentration and the gate insulator dielectric constant. The simulations are based on the Non-Equilibrium Green’s function (NEGF) method coupled with a two dimensional Poisson equation in the ballistic regime. We assume a tight-binding Hamiltonian in mode space representation. By applying proper symmetric source and drain doping concentrations, It is observed that the GNRFET with low doping concentration has higher transconductance, lower Subthreshold Swing, lower Off-current (Ioff), and higher ratio of On-current to Off-current (Ion/Ioff). Moreover, The GNRFET with high doping concentration has smaller quantum capacitance, higher intrinsic cut-off frequency, and lower gate capacitance in comparison with low doping GNRFET. As we know, Selection of a suitable gate dielectric constant is important in determining device performance. The results indicate that the GNRFET with high dielectric constant has higher transconductance, lower Off-current, higher On-current and higher ratio of Ion/Ioff in comparison with low dielectric GNRFET. Furthermore, the GNRFET with low dielectric constant has smaller capacitances in gate, drain and source. The GNRFET with high dielectric constant has lower Sub-threshold Swing.