Large Area Silicon Carbide Vertical JFETs for 1200 V Cascode Switch Operation

Abstract

SiC VJFETs are excellent candidates for reliable high-power/temperature switching as they only use pn junctions in the active device area where the high-electric fields occur. VJFETs do not suffer from forward voltage degradation, exhibit excellent short-circuit performance, and operate at 300°C. 0.19 cm2 1200 V normally-on and 0.15 cm2 low-voltage normally-off VJFETs were fabricated. The 1200-V VJFET outputs 53 A with a forward drain voltage drop of 2 V and a specific onstate resistance of 5.4 mΩ cm2. The low-voltage VJFET outputs 28 A with a forward drain voltage drop of 3.3 V and a specific onstate resistance of 15 mΩ cm2. The 1200-V SiC VJFET was connected in the cascode configuration with two Si MOSFETs and with a low-voltage SiC VJFET to form normally-off power switches. At a forward drain voltage drop of 2.2 V, the SiC/MOSFETs cascode switch outputs 33 A. The all-SiC cascode switch outputs 24 A at a voltage drop of 4.7 V.