Reliability of gamma-irradiated silicon carbide devices and circuits

Electronics for space, nuclear and accelerator systems must work close to sources of heat and radiation, without heavy shielding or cooling. 4H-SiC bipolar technology is a strong candidate: its wide bandgap (3.26 eV), roughly 2.2 times lower electron-hole pair yield than Si, and strong Si-C bond give an intrinsic advantage, and earlier KTH work showed SiC TTL circuits surviving very high doses. Survival is, however, not qualification. In Si bipolar technology the total-ionizing-dose (TID) response is known to depend on bias and dose rate (enhanced low-dose-rate sensitivity, ELDRS). This work summarizes a systematic study of how bias state, dose rate, temperature and oxide/interface processing govern the gamma response of 4H-SiC bipolar junction transistors (BJTs) and monolithic TTL inverters from the KTH bipolar process.