High power GTO with high turn-off ruggedness

A 6 kV, 6 kA pnpn type GTO was fabricated and its turn-off failure mechanism was investigated. Current concentration progressed remarkably in the fall period according to a simulation model. The homogenizing GTO segment on-state voltage was effective for reducing the current concentration. The maximum controllable current was increased by a factor of 1.2 by introducing a homogeneity fabrication process.