Diffusion-limited saturation current of a finite p-n junction

We present a quantitative analysis of the diffusion-limited saturation current of a finite planar p-n junction. In addition to the current that is given by Shockley’s analysis for a junction with infinite extent, there is a contribution from the periphery of the device. In many cases of practical interest the net effect may be approximated by considering the junction area to be supplemented by a border with width equal to one half the minority-carrier diffusion length of the surrounding semiconductor. This simple result may be modified by the effects of finite specimen thickness, reduction of the junction dimensions to values less than the diffusion length, and the proximity of other p-n junctions. Our analysis includes the effects of these parameters.