Optimization of the MPS rectifier via variation of Schottky region area

The authors discuss the optimization of the switching characteristics of the MPS (merged PIN/Schottky) rectifier by varying the relative area of the P-N junction and Schottky regions. Extensive two-dimensional numerical simulations have been performed of the forward condition and reverse recovery switching characteristics. It has been found that a trade-off curve between the forward voltage drop and the reverse recovery time can be obtained by varying the area of the Schottky region, while maintaining a constant minority carrier lifetime. This trade-off curve is superior to that obtained for the PIN rectifier using lifetime control. Experimental data that corroborate this theoretical prediction have been obtained by fabrication of 700 V devices. This method of performing the trade-off between the forward drop and the turn-off time has the advantage that it can be done by device design without the problems and additional processing cost associated with lifetime control