6-kV, 5.5-kA light-triggered thyristor

A 6-kV, 5.5-kA light-triggered thyristor has been developed for BTB (back-to-back) converter systems. A double-diffused p emitter structure was used to improve the trade-off relationship between on-state voltage and blocking capability, and a high-injection low-lifetime structure was used to improve the trade-off relationship between on-state voltage and reverse recovery charge. The double-diffused p emitter consists of a thin p⁺ emitter in the main area and a thick p^- emitter there and elsewhere. High injection was achieved by increasing the p⁺ emitter concentration and decreasing the p^- emitter thickness. A locally controlled lifetime profile was used to compensate for the high injection efficiency. These structures decreased the on-state voltage by about 0.15 V