Modeling of high-dose-rate transient ionizing radiation effects in bipolar devices

We have developed a dynamic model for photoelectric effect in bipolar devices exposed to a wide range of ionizing radiation intensities. We represent the stationary and dynamic photocurrents by current sources in parallel with each p-n junction. These sources include the prompt photocurrent of the depletion regions and the delayed response associated with the buildup and discharge of excess charge carriers in the quasi-neutral (q-n) regions adjacent to the junctions. The latter are described in terms of dynamic delay times for each q-n region, which can be represented by RC equivalent delay circuits. The model has been implemented in the circuit simulator AIM-Spice and has been verified by numerical simulations.