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; β 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 β 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 phe-nomena were observed: Ic–Ic0 will increase after the radiation of 7 000 krad in less than 0.65 V and as will β in less than 0.75 V. The mechanism of radiation-induced change in DC characteristics 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 l×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 4×10~10 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.
