Performance of Wide-Bandgap Gallium Nitride vs Silicon Carbide Cascode Transistors

Wide-bandgap (WBG) cascodes combine the advantages of gate drivability and reliability of silicon MOSFETs with the conversion efficiency of WBG devices. In cascodes, a low voltage silicon MOSFET drives a vertical SiC JFET or a lateral GaN HEMT. This paper will present the first systematic comparison of the WBG cascodes considering static & dynamic performance, 3 rd quadrant operation and avalanche ruggedness, as well as the temperature sensitivities. The results show that the GaN cascode outperforms the SiC cascode in switching performance, however, demonstrates is more temperature sensitive at on-state. A model is developed to predict the dI DS /dt and its derivative against R G . Whilst turn-ON dI DS /dt and dV DS /dt have positive temperature coefficients in the SiC cascode and negative coefficients in the GaN cascode, the SiC cascode is more avalanche rugged, whereas the GaN cascode is incapable of unclamped inductive switching.