Modeling Fermi Level Effects in Atomistic Simulations

In this work, variations in electron potential are incorporated into a Kinetic Lattice Monte Carlo (KLMC) simulator and applied to dopant diffusion in silicon. To account for the effect of dopants, the charge redistribution induced by an external point charge immersed in an electron (hole) sea is solved numerically using the quantum perturbation method. The local carrier concentrations are then determined by summing contributions from all ionized dopant atoms and charged point defects, from which the Fermi level of the system is derived by the Boltzmann equation. KLMC simulations with incorporated Fermi level effects are demonstrated for charged point defect concentration as a function of Fermi level, coupled diffusion phenomenon and field effect on doping fluctuations. INTRODUCTION Kinetic Lattice Monte Carlo (KLMC) simulations study diffusion/clustering of defects in silicon at a microscopic level [1,2]. Simulations are performed on a silicon (diamond) lattice structure with impurities and point defects mapped to lattice sites. The system evolves through transitions from one atomic configuration to the next, by virtue of point defect migration/reaction. The rates of these transitions are determined by the migration barriers combined with changes in system energy associated with transitions: