Fig. 1. (Color online) (a) Conventional SiC MOSFET. (b) Hk SiC MOSFET. (c) SJ SiC MOSFET. (d) Proposed Hk-SJ-SBD SiC MOSFET.

Fig. 2. (Color online) (a) BVs of the conventional MOSFET and Hk MOSFET with different permittivity of high-k insulators. (b) BVs of the proposed Hk-SJ-SBD MOSFET with different permittivity of high-k insulators. (c) BVs of differentN_d,N_CSL,N_p in SJ MOSFET and proposed Hk-SJ-SBD MOSFET (k = 30).

Fig. 3. (Color online) (a) Breakdown voltage of SJ MOSFET and proposed Hk-SJ-SBD MOSFET at differentN_d andN_CSL. (b) Breakdown voltages versus the deviation ofN_d for SJ MOSFET and proposed Hk-SJ-SBD MOSFET.

Fig. 4. (Color online) Equipotential line distributions of (a) the conventional MOSFET, (b) the Hk MOSFET, (c) the SJ MOSFET, and (d) the proposed Hk-SJ-SBD MOSFET (50V/line) at their own breakdown voltage.

Fig. 5. (Color online) Electric field distributions of the oxide at the trench corner of (a) the conventional MOSFET, (b) the Hk MOSFET, (c) the SJ MOSFET, and (d) the proposed Hk-SJ-SBD MOSFET at their own breakdown voltages.

Fig. 6. (Color online) Electric field distributions along the dotted lineab of the four devices at their own breakdown voltages.

Fig. 7. (Color online) Three-dimensional electric field distributions of the (a) the conventional MOSFET, (b) the Hk MOSFET, (c) the SJ MOSFET, and (d) the proposed Hk-SJ-SBD MOSFET at their own breakdown voltages.

Fig. 8. (Color online) Breakdown voltages at different interface charge densities in SJ MOSFET, Hk MOSFET and proposed Hk-SJ-SBD MOSFET.

Fig. 9. (Color online)I–V curves of the four devices atV_GS = 20 V.

Fig. 10. (Color online) Current density distributions atV_GS = 20 V,V_DS = 2 V of (a) the conventional MOSFET, (b) the Hk MOSFET, (c) the SJ MOSFET, and (d) the proposed Hk-SJ-SBD MOSFET.

Fig. 11. (Color online)R_on,sp results of the Hk MOSFET, SJ MOSFET and conventional MOSFET compared with that of the proposed Hk-SJ-SBD MOSFET device.

Fig. 12. (Color online) (a) Reverse conduction characteristics of the four devices. (b) Reverse recovery characteristics and the simulation circuit diagram of the four devices.

Fig. 13. (Color online) (a) the drain-gate capacitance (C_gd) and (b) the drain-source capacitance (C_ds) of the conventional MOSFET, Hk MOSFET, SJ MOSFET and proposed Hk-SJ-SBD MOSFET.

Fig. 14. (Color online) (a) Simulation circuit of four SiC MOSFET switching transients (R_G = 5 Ω). (b) Switching performances of the four SiC MOSFETs. (c) Switching loss (E_on +E_off) of the four SiC MOSFETs.

Fig. 15. (Color online) Trade-off relationship between theR_on,sp and BV of the four SiC MOSFET devices and other SiC MOSFET devices.

Fig. 16. (Color online) Brief fabrication process flow of the proposed 4H-SiC Hk-SJ-SBD MOSFET. (a) The process starts with a SiC epitaxial wafer. (b) Deep trench etching and ion implantation to form p-type region. (c) Gate trench etching and p-type region etching. (d) Ion implantation and annealing to form p-base, n⁺ and p⁺ regions, respectively. (e) Deposition of high-k insulating layer, depositing the trench bottom source metal, formation of gate oxide by atomic layer deposition (ALD) and deposition of polysilicon by chemical vapor deposition (CVD) to form the gate. (f) Drain and surface source metal deposition and annealing to form Schottky and ohmic contacts.