Application of the equivalent circuit model for semiconductors to the study of Au-doped p-n junctions under forward bias

Abstract

The Green-Shewchun method of solution is applied to the transmission line circuit model of Sah to obtain the forward current-, capacitance-, and conductance-voltage characteristics of semiconductor p-n junctions. Numerical solutions are obtained for diffused dopant impurity profiles and several position dependent concentration profiles of gold recombination centers to illustrate the variation of the reciprocal slope parameter m in the dc current, exp (qV/mkT). A new behavior of m = 2 is observed for many decades of current in the low-level range when the recombination centers are concentrated at the edge of the space-charge layer as expected from ion implantation. The theoretical calculations are compared with experimental forward current-, conductance-, and capacitance-voltage data from 10 to 106Hz and 77 to 300 K. Excellent agreements are obtained without adjustable parameters for boron and gold diffused p+-n silicon diodes from low to high injection levels. A twenty-five fold increase of the steady-state hole lifetime from low to high injection level is both observed and predicted. Agreements are also obtained for phosphorus- and gold-diffused n+-p silicon diodes from low to intermediate injection levels where the steady-state electron lifetime is nearly constant and controlled by electron capture into the positively charged gold donor centers.