A step-varied 6.5 kV silicon carbide terminal design to improve the breakdown voltage and electric field

This paper proposed a step-varied 6.5 kV SiC field limiting ring (FLR) termination structure, which features six distinct ring structural characteristics. Especially, the ring width decreases as the distance from the active region increases, while the loop spacing exhibits the opposite trend. The junction depth was initially investigated for the proposed and conventional structures without a field plate to ensure the breakdown voltage is higher than 8150 V. Then, the field plate is combined to further improve the blocking characteristics. The proposed structure performs a much lower maximum electric field strength and uniform distribution compared to the conventional one. Finally, the oxide trapped charge effects are introduced, while the proposed structure exhibits a weaker reduction in breakdown voltage, indicating it is suitable for high-voltage applications and long-term reliability.