X-ray irradiation and bias effects in fully-depleted and partially-depleted SiGe HBTs fabricated on CMOS-compatible SOI

X-ray total ionizing dose effects in both fully-depleted and partially-depleted SiGe HBT-on-SOI transistors are investigated at room and at cryogenic temperatures for the first time. Devices irradiated in grounded and forward-active mode configurations exhibit a different behavior depending on the collector doping of the device. The degradation produced by 10 keV x-rays is compared to previously reported 63 MeV proton results on the same fully-depleted SiGe HBT-on-SOI devices, showing decreased degradation for proton irradiation. Both collector and substrate bias are shown to affect the two-dimensional nature of the current flow in these devices, resulting in significant differences in the avalanche multiplication characteristics (hence, breakdown voltage) across temperature. © 2006 IEEE.