High injection in narrow uniform p-n junctions: A second-approximation model

The classical first-approximation high-injection theory in narrow uniform p-n junctions is based on two restrictive assumptions: negligible majority carrier current in the less-doped region (the theory applies to one-sided junctions only) and quasi-neutrality outside the space-charge layer. It has been shown in the literature that, in order to remove both assumptions, numerical integration methods are required. A second-approximation model is proposed in this paper, in which only the first of the two assumptions is removed. This model approaches the accuracy of the exact numerical solution, while still retaining all the advantages of the classical theory, i.e., the availability of analytical solutions and a better physical understanding of the high-injection phenomenon. Furthermore, the proposed model is not restricted to one-sided junctions only.