Suppressing the Reverse Recovery of Si Super-Junction MOSFET with a Low-Voltage GaN HEMT in a Cascode Configuration

The pn-junction body diode of Si super-junction MOSFET (SJ-MOSFET), when turned ON for reverse conduction, will result in a reverse-recovery process that exacerbates the switching loss. In this work, a cascode GaN/Si-SJ structure based on a high-voltage Si SJ-MOSFET and a low-voltage GaN HEMT is first proposed to suppress SJ-MOSFET's reverse-recovery process. Experiment results verified that the reverse-recovery charge ($Q_{\text{rr}}$) of a Si SJ-MOSFET can be suppressed by 98% with the cascode structure, reducing the overall switching loss by 50% at high current levels.