Study of discrete doping-induced variability in junctionless nanowire MOSFETs using dissipative quantum transport simulations

Abstract

The impact of discrete doping in junctionless gate-all-around n-type silicon nanowire transistors is studied using 3-D nonequilibrium Green's functions simulations. The studied devices have a 20 nm long gate and cross sections of 4.2 x 4.2 and 6.2 x 6.2 nm(2). The average doping concentration is 1020 cm(-3). The dopant distributions are randomly generated and modeled in a fully atomistic way. Phonon scattering, elastic and inelastic, is also included in the simulations. We show that junctionless nanowire transistors have a much higher subthreshold variability than their inversion mode counterparts for the equivalent geometry and doping level.