Investigation of Total Ionizing Dose Radiation Effects on SiC MOSFETs by Modulating the Nitrogen Content in Gate Oxide Processing

Nitric oxide (NO) annealing was commonly employed to reduce the interface state density of SiC MOSFETs in industrial. However, the introduction of hole traps by NO annealing might deteriorate the radiation characteristics of SiC MOSFETs. In this paper, we introduced varying amounts of nitrogen (N) elements into the gate oxide of SiC MOSFETs and MOS capacitors through different gate oxidation processes and conducted gamma-ray irradiation experiments with doses up to 2000 krad. We discussed the effects of different N element content in the gate oxide on the static performance of the devices after irradiation, and extracted the change of trapped charges in gate oxide after irradiation. It found that introducing rich concentration of N elements into gate oxide leads to more severe degradation in the performance of SiC MOSFETs after irradiation, for the reason of more gate oxide-trapped charges under irradiation. Additionally, it also introduced more hole traps in the gate oxide, thereby reducing the gate oxide layer lifetime of the MOSFETs after irradiation.