Avalanche injection in high voltage Si P-i-N diodes measurements and device simulations

Measurements have been performed with a new experimental technique using optical excitation for studying avalanche injection during reverse recovery in a power diode. Effects on the diode Safe Operating Area (SOA) caused by the junction termination design can be neglected in the experiments because the optical excitation of carriers is restricted only to the central region of the diode. Measurements can be done in different diode areas, making it possible to do several SOA measurements on one diode. 1D device simulations fail to predict the turn-off failure which is observed in measurements. In the performed experiments, turn-off failure occurs at a power density varying between 500 kW/cm² at 800 V and 300 kW/cm² at 1200 V, and occurs after peak power which for some measurements is as high as 700 kW/cm². A comparison between these measurements and published results for the onset of avalanche injection in bipolar power transistors and Gate Turn-Off thyristors (GTOs) indicate a wider SOA for the power diode