Quantum simulation study of single halo dual-material gate CNTFETs

For the first time, a novel single halo dual-material gate carbon nanotube Field-Effect Transistors (CNTFETs) with doped source and drain extensions is proposed and simulated using quantum simulation. The simulations are based on two-dimensional non-equilibrium Green’s functions (NEGF) solved self-consistently with Poisson’s equations. Comparisons are made for electrical characteristics among four CNTFETs structures, which are conventional single-material-gate CNTFETs (C-CNTFETs), halo single-material-gate CNTFETs (HALO-CNTFETs), dual-material-gate CNTFETs (DMG-CNTFETs), and halo dual-material-gate CNTFETs (HALO-DMG-CNTFETs). The results show that the HALO-DMG structure decreases significantly the leakage current and increases on–off current ratio as well as cutoff frequency. It is also demonstrated that HALO-DMG structure possesses two perceivable steps in potential profile of the channel, which leads to another lateral electric field peak inside the channel, thus improve both carrier efficiency and the immunity against short-channel effects (SCE). Finally, the high-frequency characteristics of the CNTFETs have been discussed based on the channel vertical electric field distributions. The parasitic capacitance has a great influence on the cutoff frequency, and limits the RF performance of the device.