Impact of Scaling Gate Insulator Thickness on the Performance of Carbon Nanotube Field Effect Transistors (CNTFETs)

As scaling down Si MOSFET devices degrade device performance in terms of short channel effects. Carbon nanotube field effect transistor (CNTFET) is one of the novel nanoelectronics devices that overcome those MOSFET limitations. The carbon nanotube field effect transistors (CNTFETs) have been explored and proposed to be the promising candidate for the next generation of integrated circuit (IC) devices. To explore the role of CNTFETs in future integrated circuits, it is important to evaluate their performance. However, to do that we need a model that can accurately describe the behavior of the CNTFETs so that the design and evaluation of circuits using these devices can be made. In this paper, we have investigated the effect of scaling gate insulator thickness on the device performance of cylindrical shaped ballistic CNTFET in terms of transfer characteristics, output characteristics, average velocity, gm/Id ratio, mobile charge, quantum capacitance/insulator capacitance, drive current (Ion), Ion / Ioff ratio, transconductance, and output conductance. We concluded that the device metrics such as Ion, Ion / Ioff ratio, transconductance, and output conductance increases with the decrease in gate insulator thickness. Also, we concluded that the gate insulator thickness reduction causes subthreshold slope close to the theoretical limit of 60 mV/decade and DIBL close to zero at room temperature.