Comparitive study of electrical properties of carbon nano tube (CNT) and silicon nanowire (SNW) MOSFET devices

Abstract

Metal oxide semiconductor field effect transistor (MOSFET) is a semiconductor device used in many electronic devices for amplification and switching electrical signals. MOSFET downscaling has been the driving force towards the technological advancement, but continuous scaling down of MOSFET causes problem of high power dissipation, high leakage current, Short Channel Effects (SCEs), excessive process variation and reliability issues. In this work, comparative study of electrical properties of carbon nanotube (CNT) and silicon nanowire (SWN) were carried out using CNT and SNW as channel materials, silicon dioxide as the gate dielectric, silicon substrate as base material. The analysis is carried out using FETTOY simulating software for oxide thickness (0.3,0.5,0.7,0.9 and 1.2nm). The results show that carbon nanotube channel material have highest transconductance (g_m) of 1.00 x 10^-4S, highest conductance (g₄) of 4.00 x 10^-6S, highest carrier injection velocity (v_inj)of 5.43 x 10 ⁵m/s, highest on current (Ion) of 59.79uA, at oxide thickness of 0.3nm when used as MOSFET device and improved short channel effects with subthreshold swing (S) of 67.79 mV/dec and drain induced barrier lowering (DIBL) of 39.67. More results such as drain current (I_d) versus gate voltage ( V_g) , quantum capacitance (QC) versus gate voltage (V_g) , and average velocity of mobile electron versus gate voltage (V_g) for all devices are also investigated. Various results obtained indicate that CNT has the higher performance of decreasing gate capacitance with decrease in oxide thickness ( T_Ox) in deep nanometer regime. This decrease in gate capacitance is observed at a gate voltage of 0.5V and above which leads to the reduction of propagation delay, lower leakage current, low power dissipation, short channel effects (SCEs) as compared to silicon nanowire MOSFET device.

KEYWORDS: Ballistic nanoscale MOSFET, Channel materials, FETTOY simulating software, Short channel effects (SCEs), Drain Induces Barrier Lowering (DIBL)