Design and Application of High-Voltage SiC JFET and Its Power Modules

This paper presents the structural design, prototype development, and testing of high-voltage silicon carbide (SiC) trenched-and-implanted vertical JFETs. Key design factors including drift layer doping concentration and thickness, channel dimensions, and termination structures are studied with numerical simulations. Devices are then fabricated in our research level facilities. The fabricated device has an active region of 4 mm(2) and can conduct a current of 2.8 A at a drain voltage of 3 V and a gate bias of 2.9 V. With a negative gate bias of -5 V, the breakdown voltage is over 4500 V. Based on these devices, two modules are designed and developed. One is a 4500 V/50-A SiC JFET power module. The other one is an all-SiC power module with SiC JFETs and SiC JBS diodes. And the second one is also evaluated in a high-frequency boost converter. The testing results show that this All-SiC module is capable of working at a frequency up to 100 kHz with both turn-on and turn-off time less than 150 ns. A high converter efficiency of 97% is obtained at a 50-kHz switching frequency and the efficiency is 95% at a switching frequency of 100 kHz. This paper demonstrates that the SiC JFET and its power module can be used for SiC device applications in medium-voltage range.