A Comparative Study of MOSFET (Single and Double Gate), Silicon Nanowire FET, and CNTFET by Varying the Oxide Thickness

Abstract

In this work, performance analysis of electrical properties of the single gate MOSFET (SG-MOSFET), double-gate MOSFET (DG-MOSFET), silicon nanowire FET (SNWFET) and carbon nanotube FET (CNTFET) devices is done using FETTOY simulator at room temperature by varying the oxide thickness for 0.3, 0.7 and 1.2 nm. The electrical parameters include average velocity, quantum capacitance, ratio of transconductance/drain current and drain current. The simulation for CNTFET and SNWFET were carried out using CNT and SNW as channel materials, silicon dioxide as the gate dielectric, and silicon substrate as a base material. Quantum capacitance has an impact in calculating the gate capacitance of a FET device at nanometer scale. The simulations performed show that CNTFET has 35% better average velocity when compared to SNWFET for 0.3 nm oxide thickness. The average velocity of DG-MOSFET and SG-MOSFET is zero. It was also observed that with the increase in gate oxide thickness, average velocity decreases. CNTFET and DG-MOSFET have 12.6 and 52% better drain current than SNWFET and SG-MOSFET respectively. The drain current decreases with the increase in gate oxide thickness. Also, it can be observed that the quantum capacitance for CNTFET (for 0.3 nm oxide thickness at 1 V) is less than SNWFET by 6.38%. The transconductance/drain current ratio is better for DG-MOSFET which is around 1.2% more when compared to SG-MOSFET.