Neutron Dependence of Neutral Base Region Recombination

A discrete, deterministic mathematical model has been developed for the bulk base region of graded base devices that accounts for both the effects of neutron-induced recombination and built-in electric field in the base region at low, intermediate, and moderate current/injection levels. Exact expressions are developed for the bulk base recombination current and the collector current as functions of neutron fluence. EBact expressions are derived for the base recombination term and the relative rates of neutroninduced base current increase and collector current decrease. These expressions involve exponential and hyperbolic functions and are well suited for numerical computations and theoretical analysis. Damage cpefficients for the bulk base recombination current and for the collector current are computed theoretically and are experimentally verified.