Thermal breakdown in silicon p-n junction devices

Current constriction in a p-n junction under a thermal mode of breakdown is analyzed and expressions for terminal voltage and radius of constriction are derived for silicon devices. The values predicted by this model are of the same order as those observed for transistors under second breakdown; it is proposed that second breakdown in transistors is a thermal mode of breakdown which inevitably follows if energy dissipated in the avalanche mode of breakdown is large enough to increase the temperature of some portion of the junction to the intrinsic or turnover temperature of the junction.