Investigation into the Reliability of Commercial 1.2-kV SiC MPS Diodes under Surge Current and Avalanche Events

With the prospect of WBG (wide-bandgap) devices such as SiC (silicon carbide) taking the forefront to replace Si (silicon) in commercial applications, analysis must be done on surge current and avalanche energy reliability to verify the viability of replacing Si with SiC in terms of long-term reliability. Power converters and inverters are often exposed to these events due to a load short circuit or transients before reaching steady-state. It is common for power semiconductor devices such as power MOSFETs (metal-oxide-semiconductor field-effect transistors) or diodes to experience a short duration of overcurrent or overvoltage in these power switching applications. The surge current can potentially damage devices if not properly rated. Extended duration of overvoltage leads to avalanche breakdown, ending in catastrophic failure of the device. This paper investigates the surge current and avalanche breakdown capabilities of commercial SiC MPS diodes rated for 1.2 kV reverse voltage and 20 A continuous forward current. The diodes are rated for 164 A of non-repetitive surge current and 220 mJ of total avalanche energy in the dual anode shared cathode configuration. A testbed is designed and developed to test the reliability of commercial WBG diodes in surge and avalanche events. Each device is initially characterized, exposed to testing conditions, and then characterized again to monitor signs of degradation. Analysis of the data collected during and after testing was conducted to determine the reliability in commercial applications.