A Novel 4H‐SiC MOSFET With High‐K/Low‐K Dielectric for Improved Frequency Characteristics

ABSTRACT Split‐Gate MOSFET (SG‐MOSFET) is promising in power‐switching circuits due to the fast turn‐on/off speed and low switching loss. However, in higher‐frequency applications, the gate architecture needs to be changed to obtain the improved high‐frequency figure of merit (HF‐FOM) over the SG‐MOSFET. In this paper, a planar split‐gate SiC MOSFET with Low‐K (nanoporous SiCOH) gate‐source dielectric and High‐K (HfO 2 ) source field‐plate dielectric (named LHK‐MOSFET) is proposed and investigated by numerical simulations. As for the proposed MOSFET, the High‐K field‐plate dielectric helps reduce semiconductor bulk capacitance ( C SiC ), thereby reducing the gate‐drain capacitance ( C GD ). Besides, the Low‐K gate‐source dielectric helps to reduce the gate‐source insulation layer capacitance ( C IL ). When compared to the SG‐MOSFET with a source field plate (SFP‐SG‐MOSFET) and SG‐MOSFET, the gate‐drain capacitance (C GD ) of the proposed MOSFET is reduced by 35.8% and 73.0%, and the gate‐drain charge ( Q GD ) is reduced by 26.9% and 62.3%, respectively. It is calculated that the HF‐FOM () of the proposed MOSFET is reduced by 35.2% and 71.0% compared to SFP‐SG‐MOSFET and SG‐MOSFET, respectively. The improved performance indicates that the proposed device is a competitive choice for high‐frequency power electronic systems.