Improving the Reverse-Recovery Performance of Si SJ-MOSFETs With a Low-Voltage GaN HEMT in a Cascode Configuration

The high reverse-recovery charge ( Q rr ) of the Si super-junction (SJ) MOSFETs' body diode leads to exacerbated switching loss and even destructive dynamic avalanche. In this paper, we propose a GaN/Si-SJ cascode structure that combines the high-voltage Si SJ-MOSFETs with a low-voltage GaN HEMT. Benefiting from introducing GaN HEMT, the GaN/Si-SJ cascode structure features zero Q rr at moderate current levels and substantially suppressed Q rr at high current levels. Such a significant improvement in the reverse-recovery process leads to a more than 50% reduction in switching loss and significantly enhanced hard-commutation robustness simultaneously.