Comparing Hexagonal and Circular Cell designs for SiC MPS Diode: The Curvature Effect on Avalanche Capability

In this work, the avalanche ruggedness of 1200V /2A SiC MPS diodes with hexagonal and circular cells are studied through experiment, modeling analysis, and 3D- TCAD simulation. The experimental result demonstrated that the avalanche energy/current capability of the circular cell-designed MPS diode (MPS-B) exhibit higher than the hexagonal cell-designed one (MPS-A). Further analysis and simulation results both reveal the MPS-A diode with hexagonal cell design will suffer higher junction temperature rise (ΔT
j
) due to the more serious curvature effect and subsequent current/heating crowding during avalanche duration. This is adverse to the avalanche ruggedness. Therefore, it is recommend that a smoother design (such as the circular cell design in this case) is employed to replace the corner area and to alleviate the curvature effect, which helps to enhance the avalanche reliability of the SiC device.