Revised model of asymmetric p-n junctions

The standard physical model by which p-n junctions in semiconductors are generally analyzed is shown to need significant revisions when applied to strongly asymmetrical junctions, such as commonly used in diffused silicon transistor emitters and solar cells. The potential, field, and space-charge density have much wider spatial distributions on the heavily doped side than generally thought, thus, in effect, widening the ’’junction region’’ there. In addition, Auger processes on that side can reduce the minority-carrier lifetime sufficiently to cause recombination without defects in the widened space-charge region and a consequent excess junction saturation current not previously recognized.