Novel layout design of 4H-SiC merged PiN Schottky diodes leading to improved surge robustness

A method to improve the surge current capability of silicon carbide (SiC) merged PiN Schottky (MPS) diodes is presented and investigated via three-dimensional electro-thermal simulations. When compared with a conventional MPS diode, the proposed structure has a more uniform current distribution during bipolar conduction due to the help of the continuous P+ surface, which can avoid the formation of local hotspots during the surge process. The Silvaco simulation results show that the proposed structure has a 20.29% higher surge capability and a 15.06% higher surge energy compared with a conventional MPS diode. The bipolar on-state voltage of the proposed structure is 4.69 V, which is 56.29% lower than that of a conventional MPS diode, enabling the device to enter the bipolar mode earlier during the surge process. Furthermore, the proposed structure can suppress the occurrence of ‘snapback’ phenomena when switching from the unipolar to the bipolar operation mode. In addition, an analysis of the surge process of MPS diodes is carried out in detail.