Mechanisms of ionizing-radiation-induced degradation in modern bipolar devices

The perimeter dependence of ionizing-radiation-induced increases in base current in both poly-emitter and crystalline-emitter devices is examined. The increase in base current occurs at the surface near the emitter-base junction. In the poly-emitter devices, the increase in base current is due to a buildup of interface states. In the crystalline-emitter devices, the increase in base current is caused by both an increase in the interface-trap density and a spread in the field-induced depletion layer. The perimeter dependence is shown to be similar to that caused by electron-beam damage and hot-carrier stressing