Atomistic simulations of the effect of Coulombic interactions on carrier fluctuations in doped silicon

Carrier distributions associated with point charges in silicon are calculated via the quantum perturbation method and used to determine Coulombic interactions between charged defects in the presence of carrier screening. The resulting interactions are used in kinetic lattice Monte Carlo simulations of defect-mediated diffusion to study dopant redistribution and associated variations in carrier concentration. Over a broad range of doping concentrations, Coulombic repulsion between like dopants leads to ordering, resulting in a more uniform electrical potential distribution (and therefore reduced threshold voltage variations) compared with random doping, the standard condition assumed in previous doping fluctuation analyses.