Comparison of surface and bulk effects of nuclear reactor radiation on planar devices

Surface effects of nuclear reactor irradiation are separated from bulk effects, and their relative importance compared. It is shown that the rates of change of surface recombination velocity and lifetime with dose are such that at high doses surface effects have an insignificant influence on
p-n
junction recombination-generation currents compared to bulk effects. In particular, the degradation of current gain at low collector currents in reactor irradiated bipolar transistors is shown to be the result of increased recombination in the bulk rather than at the surface of the emitter-base depletion region, in contrast with the case of ionizing radiation alone.