Cut Off Frequency Variation by Ambient Heating in Tunneling p-i-n CNTFETs

Abstract

In this paper, we study the effects of ambient temperature variations on the high frequency behavior of tunneling carbon nanotube field effect transistors (T-CNTFETs). Device characteristics including transconductance, gate capacitance, and intrinsic cutoff frequency are extracted and their variations by temperature are investigated. To study and simulate a tunneling carbon nanotube field effect transistor we used self-consistent numerical solution of Poisson-Schrodinger equations and non-equilibrium Green's function method. The studies carried out on 20 nm channel length and in the range of 270 to 400°K. The results show that in T-CNTFETs by increasing the temperature, a simultaneous reduction in the transconductance (gm) and gate capacitance (Cg) is observed and there is a linear relation between them. The reduction in these two parameters causes to reduction in cutoff frequency which means the reduction in their ratio (gm/Cg) by temperature. By increasing the temperature from 270 to 400°K, at 20 nm channel length, about 33 GHz reduction in cutoff frequency is observed. Also, Simulation results show that the threshold voltage experiences slight increment, i.e. decrease in its ON-state current. In addition, the leakage current increases by increasing the ambient temperature.