The effect of the internal electric field on ionized impurity diffusion in semiconductors

Abstract

The equation for the diffusion of a singly ionized acceptor or donor impurity into a uniformly doped n- or p-type semiconductor is derived and solutions obtained by numerical integration for impurity concentrations ranging from the extrinsic to the intrinsic range. The local electric field gives rise to an effective diffusion coefficient which is concentration dependent and has a maximum value near the p-n junction. Appreciable enhancement of the diffusion of the impurity due to the local electric field is found and is most marked in the region of the p-n junction.