Performance limitations of nanowire resonant-tunneling transistors with steep switching analyzed by Wigner transport simulation

Abstract

We conducted a quantum transport simulation of nanowire resonant-tunneling field-effect transistors (NW-RTFETs) based on the Wigner function model. The current-voltage characteristics of the NW-RTFETs were compared with those of the nanowire transistors and nanowire resonant-tunneling diodes. For the selection of a gate with appropriate performance, symmetric and asymmetric gates with various lengths were tested, and a symmetric gate, covering the quantum well and barrier regions, was chosen as a main gate. The source-side asymmetric gates did not produce a negative differential resistance at low gate voltages in contrast to the symmetric or drain-side asymmetric gates. Although steep switching is achieved in the negative differential resistance region, the ON/OFF current ratio (ION/IOFF) is extremely low, compared to those of conventional transistors. In an attempt to increase the ION/IOFF ratio, the sizes of the semiconductor cylinder and the oxide tube were changed. This study discusses the requirements for increasing the applicability of steep switching.