Reverse recovery and avalanche injection in high voltage SiC PIN diodes

Measurements of the limit for safe reverse recovery was performed for high voltage 4H-SiC diodes, using a special optical experimental technique. This technique was used with the intention to minimize the influence of the junction termination region at voltages below the diode static breakdown voltage. Turn-off failures occurred for the majority of measurements after the reverse voltage had reached a constant value independent of the reverse current density. This, together with the fact that repeated turn-off failure pulses resulted in visible damage in the junction termination region, strongly indicates that the observed turn-off failures are caused by avalanche breakdown in the junction termination region. The maximum power density which could be measured for safe turn-off was 1240 kW/cm(2) (1220 A/cm(2) and 1010 V). According to numerical device simulations, the safe turn-off limit imposed by avalanche injection should not be reached for the experimentally studied diodes which have static breakdown voltages up to 1200 V.