Numerical and experimental study of the mesa configuration in high-voltage 4H–SiC PiN rectifiers**Project supported by the State Key Program of the National Natural Science Foundation of China (Grant No. 61234006), the Open Foundation of the State Key Laboratory of Electronic Thin Films and Integrated Devices, China (Grant No. KFJJ201301), and the National Science and Technology Major Project of the Ministry

Abstract

The effect of the mesa configuration on the reverse breakdown characteristic of a SiC PiN rectifier for high-voltage applications is analyzed in this study. Three geometrical parameters, i.e., mesa height, mesa angle and mesa bottom corner, are investigated by numerical simulation. The simulation results show that a deep mesa height, a small mesa angle and a smooth mesa bottom (without sub-trench) could contribute to a high breakdown voltage due to a smooth and uniform surface electric field distribution. Moreover, an optimized mesa structure without sub-trench (mesa height of 2.2 μm and mesa angle of 20°) is experimentally demonstrated. A maximum reverse blocking voltage of 4 kV and a forward voltage drop of 3.7 V at 100 A/cm2 are obtained from the fabricated diode with a 30-μm thick N− epi-layer, corresponding to 85% of the ideal parallel-plane value. The blocking characteristic as a function of the JTE dose is also discussed for the PiN rectifiers with and without interface charge.