Power diodes with active control of emitter efficiency

In bipolar devices, active control of emitter efficiency allows an improved compromise between the on-state behaviour and the turn-off characteristics. This has been previously demonstrated in lateral IGBTs and in MOSFET type diode devices operating in the third quadrant. To avoid serious trigger problems occuring in MOSFET type devices, we propose a novel anode emitter structure for diodes with controlled emitter efficiency (Emitter Controlled Diode, ECD). This is achieved by an additional gate terminal, which controls the minority carrier extraction in the p-emitter via a MOS inversion channel. A suitable pretrigger time interval of the gate signal has been determined. It has also been demonstrated that though introducing a parasitic npn transistor, the safe operation at hard turn-off is not seriously affected