Fast power rectifier design using local lifetime and emitter efficiency control techniques

Local lifetime control and emitter efficiency control techniques and their effect on static and dynamic behavior of power PiN diode are investigated in this article. Mixed-mode device circuit simulations are used in order to analyze the effect of thickness and position of a reduced lifetime region and of emitter efficiency on the diode. With reference to local lifetime control the emphasis is given on the effect of the position and of the extension of the reduced lifetime region on diode performance. The low lifetime region, result of an induced damage in the epilayer, is approximated with a rectangular shape, and is defined by its thickness, position and lifetime values. The simulations show that the optimal position for the low-lifetime region is at the beginning of the base region on the anode side, while the optimal thickness of the low lifetime region depends on the amount of lifetime killing. The simulation of PiN diodes using emitter efficiency control shows that similar performance is achieved reducing anode doping or reducing anode thickness and that main limitation to their performance is reach-through phenomenon. Both local lifetime control and emitter efficiency control design techniques are shown to be effective in reducing the turn-off time and increasing diode softness with a little worsening of on-state voltage drop.