A new SiC asymmetric cell trench metal-oxide-semiconductor field effect transistor (MOSFET) with a split gate (SG) and integrated p(+)-poly Si/SiC heterojunction freewheeling diode (SGHJD-TMOS) is investigated in this article. The SG structure of the SGHJD-TMOS structure can effectively reduce the gate-drain capacitance and reduce the high gate-oxide electric field. The integrated p(+)-poly Si/SiC heterojunction freewheeling diode substantially improves body diode characteristics and reduces switching losses without degrading the static characteristics of the device. Numerical analysis results show that, compared with the conventional asymmetric cell trench MOSFET (CA-TMOS), the high-frequency figure of merit (HF-FOM, R (on,sp) x Q (gd,sp)) is reduced by 92.5%, and the gate-oxide electric field is reduced by 75%. In addition, the forward conduction voltage drop (V (F)) and gate-drain charge (Q (gd)) are reduced from 2.90 V and 63.5 mu C/cm(2) in the CA-TMOS to 1.80 V and 26.1 mu C/cm(2) in the SGHJD-TMOS, respectively. Compared with the CA-TMOS, the turn-on loss (E (on)) and turn-off loss (E (off)) of the SGHJD-TMOS are reduced by 21.1% and 12.2%, respectively.