NEGF simulations of a junctionless Si gate-all-around nanowire transistor with discrete dopants

We have carried out 3D Non-Equilibrium Green Function simulations of a junctionless gate-all-around n-type silicon nanowire transistor of 4.2 × 4.2 nm² cross-section. We model the dopants in a fully atomistic way. The dopant distributions are randomly generated following an average doping concentration of 10²⁰ cm^-3. Elastic and inelastic Phonon scattering is considered in our simulation. Considering the dopants in a discrete way is the first step in the simulation of random dopant variability in junctionless transistors in a fully quantum mechanical way. Our results show that, for devices with an “unlucky” dopant configuration, with a starvation of donors under the gate, the threshold voltage can increase by a few hundred mV relative to devices with a more homogeneous distribution of dopants.