Attributes in the Performance and Design Considerations of Asymmetric Drain and Source Regions in Carbon Nanotube Field Effect Transistors: Quantum Simulation Study

Abstract

For the first time, in this paper the effects of asymmetric drain and source lengths and doping densities on the performance of carbon nanotube field effect transistors (CNTFETs) have been investigated. Some of main digital and analog parameters such as saturation current, leakage current, current ratio, subthreshold swing (SS), and drain-conductance have been studied. Simulation results show that ON-OFF current ratio depends on both drain and source lengths and densities. The SS value varies by source doping density and drain length but other drain and source parameters don't have conspicuous impacts on it. According to the simulation, drain-conductance depends on drain doping density and drain length. The source parameters have negligible effects on this characteristic in comparison with drain parameters. By using the results of this paper one can select CNTFET parameters to obtain more reliable device with better analog and digital characteristics. Simulation results have been obtained using quantum simulation based on self-consistently solution between two-dimensional Poisson equation and Schrödinger equation with open boundary conditions, within the non-equilibrium Green's function (NEGF) framework.