Optimization of transistor neutron tolerance

A detailed analysis has been performed for neutron-irradiated p⁺-n junction diodes to determine the influence of the recombination model, doping profile, and operating point on the minority carrier recombination throughout the devices. The calculations give the recombination rate, carrier distributions, and electric field in the various device regions and separate the device current into its space-charge-region recombination and diffusion components. At low bias levels, where space charge region recombination dominates, both the calculations and experimental data on irradiated devices show that the recombination current can be greatly reduced by employing heavy base doping in the vicinity of the junction.