Avalanche Ruggedness of Parallel Connected Diodes: SiC Schottky Diodes vs Silicon PiN Diodes

The impact of junction temperature variation between parallel connected SiC Schottky diodes and PiN diodes on the electrothermal ruggedness of the parallel pair have been studied. Parallel connected 600V SiC Schottky diodes and silicon PiN diodes have been subjected to electrothermal stress tests. The electrothermal robustness of the parallel connected pair have been studied as a function of 3 parameters: (i) The junction temperature difference between the device under test (DUTs). (ii). The avalanche duration of the UIS pulse (inductor size) and (iii). The current rating of the diodes. The results show that the maximum avalanche energy (EAVMAX) sustainable by the parallel connected DUTs exhibits the following characteristics: i) EAVMAX increases with the current rating (active area) of the diodes; ii) EAVMAX is 370% higher for the SiC Schottky diodes compared to the silicon PiN diodes in spite of the SiC diodes having a smaller current rating and hence smaller active area; iii) EAVMAX increases with the avalanche duration. This means that the safe operating area of the diodes is smaller for high current low duration UIS pulses than for low current high duration UIS pulses; iv) EAVMAX reduces with increasing variation in junction temperature (TJ2-TJ1) between the DUTs. This reduction is smaller for SiC diodes than for silicon PiN diodes, meaning that the SiC diodes are more avalanche rugged under electrothermal imbalance between parallel connected diodes.