Scaling laws and performance limitations of power turn-off devices

The performance of multiple-cell devices is limited by a redistribution of current during turn-off because minor differences between the otherwise identical cells seem to become important. A simple model based on Gaussian statistics gives a quantitative explanation of this phenomenon for the first time. For the example of a gate turn-off thyristor (GTO) it leads to an approximate square-root scaling of turn-off current with device size. Good agreement with experimental results is found. The model is not GTO-specific and may cover other devices as well