A high voltage, high current light-activated thyristor with a new light sensitive structure

To improve performance of a light-activated thyristor, its light sensitivity and dv/dt-capability were optimized by developing a novel structure of light sensistive area composed of a grooved light-incident region, n-emitter stripes and a new n-emitter shunt area. This shunt area is a by-pass of the dv/dt-induced displacement current. The relation between light-sensitivity and dv/dt-capability was studied on the basis of a quasi one-dimensional model. Applying this model for designing the structure of the light sensitive area, we developed a 4kV, 1200A light-activated thyristor composed of a tablet of 64mm diameter. This thyristor has a short turn-on delay time of 3 μsec at an incident light power of 5 mW and a high dv/dt-capability of 2000 V/μsec at a junction temperature of 125°C.