Analysis of plasma extraction transit time oscillations in bipolar power devices

The occurrence of high-frequency PETT (plasma extraction transit time) oscillations is related to the transit-time of the carrier transport through the already formed space-charge region at the end of the turn-off process of bipolar power devices. These oscillations are found only in the case of a matching external LC circuit which acts as a resonance circuit. It is shown that the occurrence of this type of oscillation depends on a wide range of parameters. 3D EMC simulation is used for the estimation of resonance points of a complete power module.