An Analytical Model for Field-Enhanced Diffusion of Ionized Impurities in Highly Doped Si

Abstract

AbstractAn expression for concentration dependence of diffusion coefficient of ionized impurity in semiconductors which is derived which is valid for the whole range of carrier degeneracy under the condition that the impurity concentration greatly exceeds the intrinsic carrier density. Due to reduction of impurity field screening by mobile carriers at degenerate conditions the diffusion coefficient is shown to be a monotonously increasing function of impurity concentration. It is proved that taking band gap narrowing into account results in a reduction of the diffusion coefficient in comparison with the case of unperturbed band structure. In addition, a decreasing concentration dependence of the diffusion coefficient can be realized at relatively low impurity concentrations.