Effect Mechanism of Dynamic Avalanche on Turn-Off Behavior and Ruggedness of IGCT

By analytical analysis and TCAD device simulation, the physical mechanisms behind the dynamic avalanche and resulting current filament during IGCT turn-off are revealed. It is demonstrated that dynamic avalanche can greatly increase the turn-off time and loss of the device, and with the $\alpha_{pnp}$ increasing, the avalanche-generated current filament becomes stronger and moves slower, which will weaken the ruggedness of the device at the turn-off.