Design and Characterization of High-Voltage Silicon Carbide Emitter Turn-off Thyristor

A novel MOS-controlled silicon carbide (SiC) thyristor device, the SiC emitter turn-off thyristor (ETO), as a promising technology for future high-voltage and high-frequency switching applications has been developed. The world´s first 4.5-kV SiC p-type ETO prototype based on a 0.36 cm² SiC p-type gate turn-off (GTO) shows a forward voltage drop of 4.6 V at a current density of 25 A/cm² and a turn-off energy loss of 9.88 mJ. The low loss shows that the SiC ETO could operate at a 4-kHz frequency with a conventional thermal management system. This frequency capability is about four times higher than the 4.5-kV-class silicon power devices. The numerical simulations and theoretical analysis have been carried out to show the potentially improved performance of the high-voltage SiC ETOs. The results show that the high-voltage (10-kV) SiC n-type ETO has much better tradeoff performance than that of the p-type ETO due to a smaller current gain of the lower bipolar transistor in the SiC n-type GTO. Further improvement of the 10-kV SiC n-type ETO can be made with the optimum design of the drift layer carrier lifetime and buffer layer doping concentration of the 10-kV SiC GTO. The theoretical analysis and numerical simulation shows the SiC ETO also has the excellent reverse bias safe operating area. The experimental and theoretical studies show that the SiC ETO is a promising candidate for high-voltage (> 5 kV) power conversion applications.