Design and optimization of linearly graded field limiting ring termination for high-voltage SiC diodes

An optimized linearly graded field limiting ring (LG-FLR) termination structure for high voltage power 4H-SiC diodes has been presented in this paper. Simulated optimized designs were performed to investigate SiC field limiting ring termination, and determine the optimum guard ring spacing for planar diodes. Simulated results show that the LG-FLR provides a smooth and uniform surface electric field distribution without field spikes. In addition, LG-FLR consumes smaller termination length than conventional FLR structures. Implanted 4H-SiC JBS diodes with optimized guard ring designs were fabricated and results correlated to simulation. Experimental breakdown values of 5 kV for LG-FLR structure with 35 rings were in good agreement with simulated results.