Detailed Lumped-Model Analysis of Transistor Ionizing Radiation Effects

Transient response of a transistor exposed to an ionizing radiation environment can be predicted solely from knowledge of the radiation environment and transistor lumped-model parameters calculated from geometrical and electrical data. Accuracy of the lumped-model transistor representation depends on the detail and accuracy of the data used for calculation of the lumped-model parameter values, an accurate representation of the carrier generation rate in the semiconductor transistor chip, and an accurate representation of the interaction of the radiation environment and the transistor leads and package. In general, we have found that the detailed transistor model represents the common emitter transient response to well within a factor of two. The transistor response is calculated from electrical and geometrical data and the measurement of the radiation intensity from a silicon PIN detector. The transistor response is considered over the entire practical range of quiescent emitter current (<10 μa to > 10 ma) and common-emitter source resistance (100 ohms to 10 kilohms).