Monolithic Reverse Blocking 1.2 kV 4H-SiC Power Transistor: A Novel, Single-Chip, Three-Terminal Device for Current Source Inverter Applications

Current sourceinverters (CSIs) require power switches with first quadrant current conduction and gate-controlled output characteristics as well as reverse blocking capability. Experimental demonstration of a SiC monolithic reverse blocking transistor (MRBT) suitable for CSI applications is described in this letter. The proposed device is based on the integration of a SiC JBS diode with a SiC power mosfet on the same chip. The cathode of the SiC JBS diode is connected to the drain of the SiC power mosfet by their common N+ substrate. The proposed device structure creates a novel SiC-based unipolar single-chip three-terminal transistor with reverse blocking capability. The measured characteristics of a 1.2 kV 4H-SiC MRBT, fabricated in a commercial six-inch wafer foundry, are reported in this letter. The devices show a diode-like on-state characteristic with a low knee voltage of 1.3 V and an on-state voltage drop of 2.8 V at 5 A. The measured reverse transfer capacitance and output capacitance for the MRBT at a drain bias of 2 and 1000 V are a factor of similar to 3x and similar to 1.6x smaller than the measured values for the internal mosfet device. Switching measurements show a 12% reduction in the gate-drain charge for the MRBT compared with the internal mosfet which is favorable for reducing switching losses.