Design and fabrication of monolithic light triggered thyristor

Light triggered thyristors (LTT) have attracted considerable attention because of their high insulation of the main circuit and the control circuit, good trigger characteristics, and high reliability. In this work, we propose and fabricate a high-power LTT with monolithic and direct-triggering structure design, triggered by infrared light with a wavelength of 940 nm. The device structure is simplified, and the step by step drive is changed to direct drive, which further improves the response speed. By improving the cathode metal structure, changing from a large area of cathode metal coverage to an interdigitated cathode structure, thus the light injection window area is increased. A reasonable cathode shorts distribution is choosed for the interdigital cathode structure to ensure [dV/dt] tolerance. The test results show that the forward repetitive peak voltages (VDRM) and reverse repetitive peak voltages (VRRM) of the device are all higher than 900V, the rise-time ($\boldsymbol{T_{rise}}$) is as short as $2.3 \mu\mathrm{s}$, the [dV/dt] tolerance is larger than $1000\ \mathrm{V}/\mu\mathrm{s}$, and the maximum optical trigger power is as low as 7 mW/cm². This upgraded LTT will be widely used in power electronic circuits because of its excellent characteristics.