A model of thep—njunction with exponential doping profile†

Abstract The exponential p-n junction shows some peculiarities, which make its theoretical study interesting. In this paper some characteristics of the transition layer of such a junction are analysed, taking into account the mobile carriers in this region. Following a method introduced by Sab, the Poisson-Boltzmann equation is linearized using a parameter α, which is a measure of the relative importance of the fixed, ionized impurity space charge compared with the mobile carrier charge in the transition layer of the p-n junction. The width of the transition layer, on the left and on the right of the junction, the built-in voltage, the total potential difference across the transition region and the total capacitance are derived. The d.c. theory of the junction capacitance is compared with experimental data obtained on implanted silicon junctions : ft satisfactory agreement is found.