Switching ruggedness and surge-current capability of diodes using the self-adjusting p emitter efficiency diode concept

The surge-current ruggedness of free-wheeling diodes can be improved by implementing the self-adjusting p emitter efficiency diode concept (SPEED). Simulations indicate that the switching ruggedness is reduced because of the occurrence of cathode-side filaments during reverse-recovery. Experiments confirm the weak switching performance of such a diode in comparison to a conventional diode. By implementing the controlled injection of backside holes concept cathode-side filaments can be suppressed. However, this measure is not sufficient to regain the switching ruggedness of a conventional diode. It is also necessary to fully embed the p+-areas of the SPEED anode in the low-doped p-type area to avoid high electrical field strengths at the p+p-junction and pinning of anode-side filaments. However, anode-side adjustments for improving the switching ruggedness can reduce the benefit of the SPEED concept regarding the surge-current capability.