RADIATION-INDUCED GAIN DEGRADATION IN LATERAL PNP BJTS WITH LIGHTLY AND HEAVILY-DOPED EMITTERS

Radiation-induced gain degradation is compared in two types of lateral PNP bipolar devices that are identical except for the emitter doping. The devices with heavily-doped emitters (1x10(20) cm(-3)) degrade les s than the devices with lightly-doped emitters (1x10(18) cm(-3)). Both device types are sensitive to interface-trap formation in the oxide a bove the emitter-base junction and the neutral base region. In additio n, the devices with lightly-doped emitters experience spreading of the depletion region into the emitter, increasing their sensitivity to to tal-dose irradiation. The gain degradation in both device types is due to a combination of increased base current and decreased collector cu rrent. The radiation-induced decrease in collector current is more sig nificant for devices from this technology than for other devices studi ed previously. Increased gain degradation is observed in heavily-doped devices irradiated at low dose rates, but the enhanced degradation ap pears to be due to time-dependent effects rather than true dose-rate e ffects. The lightly-doped devices do not exhibit a clear dose-rate tre nd and the gain of these devices improves during post-irradiation anne aling.