Improving Surge Current Capability of SiC Merged PiN Schottky Diode by Adding Plasma Spreading Layers

In this article, a novel structure design concept [plasma spreading layer (PSL)] is introduced into silicon carbide (SiC) merged PiN Schottky (MPS) diode to improve the surge current capability. Compared to the isolated P+ island design in traditional MPS diode, the P+ islands in the proposed new structure are connected by the P+ plasma spreading layers which can spread bipolar current from P+ islands to the other parts of the device during the surge pulse. Therefore, the effective conducting area of the device is increased and the energy dissipation capability can be improved. In this article, 1.2-kV SiC MPS diodes with two types of plasma spreading layers are designed and fabricated. Their forward characteristics and surge current capability are compared to traditional stripe cell and hexagonal cell designed MPS diodes. The experimental results show that, with the help of the plasma spreading layers, a 20% increase of energy dissipation capability is achieved by the new structure design, which results in a 10% improvement of the surge current capability.