A study into the applicability of p +n + (universal contact) to power semiconductor diodes for faster reverse recovery

Abstract

The use of p +n + universal contact for improving switching performance in diodes is studied in detail. A theoretical framework is described which shows that the incorporation of universal contact either at the end of the lightly doped region or in the injecting p or n regions of the diode can all be viewed as an attempt to reduce the effective minority carrier lifetime in the diode by redistributing minority carrier current from the lightly doped region of the diode where recombination lifetime is high to other regions of the diode where the presence of universal contact results in smaller recombination lifetime. It is shown that the incorporation of universal contact allows a new tradeoff between the effective recombination lifetime and the reverse blocking voltage determined by the proximity of universal contact to the lightly doped region of the diode. The impact of insertion of universal contact on reverse recovery is discussed as a function of current density and reverse blocking voltage.