Strong power-law thickness dependence of total-ionizing-dose degradation in SiC MOSFETs

This work investigates total-ionizing-dose (TID) degradation in SiC MOS capacitors and MOSFETs as a function of gate oxide thickness (Tox) and process conditions. Radiation-induced charge accumulation follows a power-law dependence on Tox (ΔVOT ∝  Tox2.8), significantly stronger than in Si devices, while interface state density remains stable—confirming that positive oxide-trapped charge dominates degradation. Reducing Tox, combined with high-temperature oxidation and short annealing, enhances TID tolerance. X-ray photoelectron spectroscopy correlates trapped charge with near-interface Si–Ox suboxides. The optimized process withstands 500 krad with ΔVTH ∼−1.1 V under positive gate bias (+18 V), far exceeding the unhardened reference device, which exhibits ΔVTH ∼−18 V and fails below 100 krad.