An Improved 4H-SiC Trench-Gate MOSFET With Low ON-Resistance and Switching Loss

Abstract

In this paper, an improved 4H-SiC U-shaped trench-gate metal–oxide–semiconductor field-effect transistors (UMOSFETs) structure with low ON-resistance ( ${R}_{ \mathrm{\scriptscriptstyle ON}}$ ) and switching energy loss is proposed. The novel structure features an added n-type region, which reduces ON-resistance of the device significantly while maintaining the breakdown voltage ( ${V}_{\textsf {BR}}$ ). In addition, the gate of the improved structure is designed as a p-n junction to reduce the switching energy loss. Simulations by Sentaurus TCAD are carried out to reveal the working mechanism of this improved structure. For the static performance, the ON-resistance and the figure of merit (FOM $= {V}_{\textsf {BR}}^{\textsf {2}}/{R}_{ \mathrm{\scriptscriptstyle ON}}$ ) of the optimized structure are improved by 40% and 44%, respectively, as compared to a conventional trench MOSFET without the added n-type region and modified gate. For the dynamic performance, the turn-on time ( ${T}_{ \mathrm{\scriptscriptstyle ON}}$ ) and turn-off time ( ${T}_{ \mathrm{\scriptscriptstyle OFF}}$ ) of the proposed structure are both shorter than that of the conventional structure, bringing a 43% and 30% reduction in turn-on energy loss and total switching energy loss ( ${E}_{\mathbf {SW}}$ ).