Power PiN diode performance improvement through local lifetime control: numerical analysis

Numerical simulations are used to analyse the effect on static and dynamic behavior of local lifetime control applied to power PiN diodes. Extended use of mixed mode device circuit simulations allows the analysis of diode behavior in realistic working conditions. In the paper 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, the result of complex damage in the epilayer, is approximated with a rectangular shape in the simulator, and is defined by its thickness, position and amount of lifetime reduction. The simulations show that the optimal position for the low-lifetime region is at the beginning of the epilayer region on the anode side, while the optimal thickness of the low lifetime region depends on the amount of lifetime reduction. The local lifetime control design technique is shown to be effective in reducing the turn-off time and increasing diode softness with a little worsening of on-state voltage drop. It is shown that the trade-off curve obtained by diodes using local lifetime control is better than the one achieved with lifetime killing in the whole epilayer region.