Effect of NO annealing on radiation detection performance of Ni/SiO2/4H-SiC MOS capacitors

In this study, Ni/SiO₂/4H-SiC metal-oxide-semiconductor (MOS) devices were fabricated, achieving high-energy resolution for alpha particle radiation detection. The SiO₂/4H-SiC interface was treated with two different methods: i) annealing in N₂ environment, ii) annealing in NO environment. Devices manufactured using the former method show lower dark currents than the latter. This difference is due to a decrease in trap density at the SiO₂/4H-SiC interface caused by NO annealing, resulting in a higher barrier height for the device. The NO-30 exhibited a much higher energy resolution of 0.46%@5486 keV compared to 0.95%@5486 keV observed in N₂-30, despite both devices exhibiting good energy linearity in response to alpha particles. The SiO₂/4H-SiC interface trap density revealed a significant decrease after NO treatment, indicating NO treatment can effectively improve the electrical performance of 4H-SiC MOS devices. CCE analysis showed the NO-30 had a lower surface recombination field (13000 V/cm) compared to N₂-30 (35000 V/cm), which improved the charge collection efficiency and energy resolution. This study provides a practical approach for enhancing the energy resolution of 4H-SiC MOS detectors.