Source-to-Drain Tunneling of Nanoscale MOSFETs at Cryogenic Temperatures by NEGF Simulation

Abstract

As the progress in the semiconductor industry downsizing the critical dimensions of devices to nanascale has played a significant role until now Thus it’s getting so closer to the fundamental limits of semiconductor physics that there are all kinds of challenges for us to conquer In this thesis the nanoMOS4 0 simulator applies the non-equilibrium Green’s function (NEGF) to solving the Schro?dinger equation for the quantum transport of electrons in a nanoscale double-gate MOSFET By the self-consistently iteration of the Schro?dinger equation and the Poisson equation we can thus obtain the electron density and current etc Because of the potential of quantum computing for the powerful computing ability and commercial feasibility the quantum computer technology has rapidly developed in recent years However how to systematically realize the quantum practicality by the controlling chips has become a big challenge Applied to the fabrication of the chips for quantum operation controlling Cryo-CMOS technology thus flourishes On the basis of calculating the quantum transport the incomplete ionization at temperatures lowering to 4 K is taken into account in the thesis Additionally the lateral doping diffusion from the process is also considered to investigate their influences on the device characteristics with the channel length decreasing It’s shown that reducing the channel length and the lateral doping diffusion extending can let the effect of incomplete ionization on the transfer characteristics more noticeable besides low temperatures Moreover the direct tunneling current crossing through the barrier between the source and drain causes the transformation in the subthreshold region and even suppresses subthreshold swing lowering at low temperatures into the saturation

Date of Award	2020
Original language	English
Supervisor	Kuo-Hsing Kao (Supervisor)