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

The high reverse-recovery charge ( Qrr ) of the Si superjunction (SJ) mosfet s’ body diode leads to exacerbated switching loss and even destructive dynamic avalanche. In this article, we propose a GaN/Si-SJ cascode structure that combines the high-voltage Si SJ- mosfet s with a low-voltage GaN HEMT. Benefiting from introducing GaN HEMT, the GaN/Si-SJ cascode structure features zero Qrr at moderate current levels and substantially suppressed Qrr 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.