Normally-Off SiC VJFETs for 800 V and 1200 V Power Switching Applications

This paper reports on the development of a normally- off 4H-SiC VJFET power switch technology suitable for drop in replacement in switching-mode power supplies (SMPS). The fabricated devices exhibited a low specific on-resistance (Ron-sp) measured at V_DS=1 V and V_Gs=2-5 V. The transistors designed for 800 V applications had R_ON-SP < 2.9 mOmegaldrcm² and R_ON-SP < 6.6 mOmegaldrcm² at 25degC and 200degC, respectively. The devices designed for 1200 V application had R_ON-SP < 4.3 mOmegaldrcm² at 25degC and R_ON-SP < 12.8 mOmegaldrcm² at 200degC. The total delay time of 73 ns was measured on a 1200 V device when switching from 600 V to 4.9 A with the gate bias ranging from 0 V to 2.75 V. The highest measured off-state drain voltage blocked by a 1200 V device at V_GS=0 V exceeded 1800 V with the total drain leakage of 1 mA.