The Performance of Operational Amplifiers Consisting of 4H-SiC CMOS After Gamma Irradiation

The operational amplifier was fabricated by 4H-SiC complementary MOS on the same die for sensors installed in nuclear power plants, and it showed over 100× the radiation resistance compared with Si bipolar junction transistors. The closed-loop gain at 50 kGy was 11% lower than it of preirradiation because the allowable output voltage range became small by the threshold voltage degradation of p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs), and the offset voltage became unstable when the gamma integral dose was beyond 30 kGy. To reduce the influence of gamma irradiation, we propose a MOSFETs structure which features both thin gate oxide and field plate electrodes connected to an isolation layer. We evaluated the proposed isolation structure using the single device, and our experiments confirmed that the proposed isolation structure has potential of gamma irradiation resistance of 100 kGy.