Improvement of power rectifier and thyristor characteristics by lifetime control

It is shown that the ratings of rectifiers can be optimized by maximizing the ratio of the high level to the low level lifetime. An optimization criterion relating the recombination center location to its capture cross-section ratio for holes and electrons is derived. In the case of thyristors, the leakage current must also be considered in the optimization. This results in a criterion which relates the recombination center location to the resistivity and capture cross-section ratio. In addition, it is shown that the ideal recombination center must have large capture cross-sections for holes and electrons, a large capture cross-section ratio, and must lie at about 0.70 eV above the valency band in order to fabricate devices with good forward voltage drop - reverse recovery time trade-off characteristics and low leakage currents over a broad range of resistivities and operating temperatures.