Nonlinearity Analysis of Quantum Capacitance and its Effect on Nano-Graphene Field Effect Transistor Characteristics

Abstract

A simple, compact, and fundamental physics-based quasi-analytical model for single-layer graphene field effect transistors (GFETs) with large-area graphene is presented using a quantum mechanical density gradient method-based calculation. The device statistical physics of the two-dimensional (2D) graphene channel is studied analytically. This modelling leads to the precise drain current of the GFETs. The drain current calculation for the GFETs starts from charge carrier concentration, its density of states, and quantum capacitance (QC). QC depends primarily on the channel voltage, and is also a function of the gate-to-source voltage Vgs and drain-to-source voltage Vds. The formulation of the drain current with velocity saturation was carried out using the Monte Carlo simulation method. The performance of the analytical GFET model is characterized by the precise values of QC, its impact on drain current, and output characteristics. The impact of QC on FET devices at nanoscale is that it adds nonlinearity to the characteristic curves. The proposed method provides better QC results than the available analytical and simulated models.