The changes of DC characteristics of SiGe HBT after being submitted to γ-ray irradiation of 700 krad, 7 000 krad and 10 000 krad were compared to those of Si BJT. Generally speaking, Ib and Ib- Ib0 increase with the doses increasing. For SiGe HBT, with the doses increasing, Ic and Ic-Ic0 as well as the related changes of the current gain （β） will decrease at higher Vbe, while for Si BJT, with the doses increasing, after irradiation, Ib and Ic-Ic0 increase; ,8 and its related changes also decrease with their differences, however, tending to be very small at high doses of 7 000 krad and 10 000 krad. Moreover, given the same doses, the decreases of,a are much larger than SiGe HBT, which shows that SiGe HBT＇s anti-radiation performance proves to be better than Si BJT. Still, in SiGe HBT, some strange phenomena were observed： Ic-Ic0 will increase after the radiation of 7 000 krad in less than 0.65 V and as will ,8 in less than 0.75 V. The mechanism of radiation-induced change in DC characteristies was also discussed.
MENG Xiang-tiHUANG QianWANG Ji linCHEN Pei-yiTSIEN Pei-hsin
The 9 and 12 MeV proton irradiations of the Chinese CMOS Image Sensor in the fluence range from 1× 10^9 to 4×10^10 cm^-2 and 1 × 10^9 to 2×10^12 cm^-2 have been carried out respectively. The color pictures and dark output images are captured, and the average brightness of dark output images is calculated. The anti-irradiation fluence thresholds for 9 and 12 MeV protons are about 4×10^l0 and 2×10^12 cm^-2, respectively. These can be explained by the change of the concentrations of irradiation-induced electron-hole pairs and vacancies in the various layers of CMOS image sensor calculated by the TRIM simulation program.
