Fast power switching with cascode diamond MOSFET–SiC MOSFET/GaN HEMT complementary half-bridge inverter

For expanding vehicle electrification and the use of renewable energy, high power density inverters are required. One of the ways to achieve high power density is by enhancing the switching frequency on the inverters, which can reduce the volume of passive components. By accelerating the switching frequency, the dead time ratio in one switching cycle increases, and dead time issues such as higher conduction losses caused by diode current become conspicuous. The dead time issues consequently limit the switching frequency on the inverters. Complementary inverters, which consist of n- and p-channel field effect transistors (FETs) in the same leg, have been proposed to resolve the issues by automatically minimizing the dead time. The n- and p-channel FETs, which exhibit equivalent performance, are required to fabricate the complementary inverters. However, wide-bandgap semiconductors such as SiC and GaN are unsuitable for the p-channel FETs because of their deep acceptor levels and low hole mobility. In contrast, diamond is the most promising candidate for the p-channel FETs due to its superior physical properties. In this study, a complementary half-bridge inverter was fabricated using a cascode diamond MOSFET and either an SiC MOSFET or a GaN HEMT, and fast power switching on the complementary half-bridge inverter with no intentional dead time at 100 kHz was successfully demonstrated. This result indicates that complementary inverters using diamond MOSFETs have the potential to overcome the dead time issues and achieve higher power density.