Schematic diagram of the n-type GAA Si NW MOSFET. Discrete distributions of the active As atoms are introduced into the S/D extensions. To mimic metal electrodes, the S/D regions are heavily doped with Nd = 5 × 1020 cm−3 (continuously doping). The channel region is intrinsic. We simulated 100 samples using 200 different random seeds (each sample needs two random seeds for S/D extensions).