Static, Dynamic, and Short-circuit Characteristics of Split-Gate 1.2 kV 4H-SiC MOSFETs

Abstract

This paper reports static, dynamic, and short-circuit characteristics of split-gate (SG) 1.2 kV 4H-SiC MOSFETs. Conventional (C) MOSFETs and SG-MOSFETs were fabricated and evaluated. Identical conduction behaviors were achieved due to them having the same cell pitch. Although the maximum electric field in the gate oxide is higher in the SG-MOSFETs, this both device architectures obtained similar breakdown voltages with low leakage current. Due to the structure of the split-gate, the reverse capacitance <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathbf{C}_{\mathbf{rss}})$</tex> was reduced by 32 % when compared to conventional MOSFETs. As a result, switching loss for turn-on and turn-off transients was reduced, and thus total switching loss was reduced by 25 % in the SG- M OSFE Ts. Finally, the short-circuit (SC) ruggedness of the MOSFETs were evaluated. Even though the maximum drain current is higher in the SG-MOSFETs, under SC condition, a similar short-circuit withstand time (SCWT) was obtained. In order to further investigate short-circuit characteristics, non-isothermal simulations were conducted. It was discovered that there is no issue with the exposed edge of the gate in SG- M OSFE Ts under SC conditions despite the high electric field in gate oxide. Significantly reduced energy loss was achieved in the SG-MOSFETs with no compromise in static and short-circuit characteristics compared to the conventional MOSFETs.