Self-protection functions in direct light-triggered high-power thyristors

Abstract Direct light-triggered thyristors with integrated protection functions were fabricated and investigated. It is shown that the simultaneous integration of the light-trigger function and a reliable overvoltage self-protection can be achieved by integrating a diode into the centre of the thyristor. In addition, a d V /d t self-protection function can be integrated by a proper adjustment of the d V /d t capability of the amplifying gates and the main cathode area, ensuring a safe turn-on of the thyristor when a voltage pulse with a d V /d t value exceeding the maximum d V /d t value is applied to the device. Thyristors with different breakdown voltages ranging from 5 to 8 kV on 2-, 4- and 5-inch wafers have been realised.