A Novel Silicon Carbide (SiC) MOSFET with Diode Integration Technology

MA Chao; CHEN Weizhong; ZHANG Bo

doi:10.11999/JEIT250180

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MA Chao, CHEN Weizhong, ZHANG Bo. A Novel Silicon Carbide (SiC) MOSFET with Diode Integration Technology[J]. Journal of Electronics & Information Technology. doi: 10.11999/JEIT250180

Citation:

MA Chao, CHEN Weizhong, ZHANG Bo. A Novel Silicon Carbide (SiC) MOSFET with Diode Integration Technology[J]. Journal of Electronics & Information Technology. doi: 10.11999/JEIT250180

MA Chao, CHEN Weizhong, ZHANG Bo. A Novel Silicon Carbide (SiC) MOSFET with Diode Integration Technology[J]. Journal of Electronics & Information Technology. doi: 10.11999/JEIT250180

Citation:

MA Chao, CHEN Weizhong, ZHANG Bo. A Novel Silicon Carbide (SiC) MOSFET with Diode Integration Technology[J]. Journal of Electronics & Information Technology. doi: 10.11999/JEIT250180

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A Novel Silicon Carbide (SiC) MOSFET with Diode Integration Technology

doi: 10.11999/JEIT250180

MA Chao^{1
,
,},
CHEN Weizhong^{2, 3},
ZHANG Bo¹

1.
The State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
2.
College of Electronics Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
3.
Chongqing Integrated Circuit Collaborative Innovation Center, Chongqing 400065, China

Funds: Chongqing Nature Science Foundation of China (CSTB2024NSCQ-MSX1069), Chongqing Innovation and Application of Major Projects (CSTB2023TIAD-STX0014)

Received Date: 2025-03-18
Rev Recd Date: 2025-03-31

Available Online: 2025-04-09

Abstract

Abstract

This paper proposes a novel double-trench Silicon Carbide (SiC) MOSFET that integrates a Schottky diode structure to improve reverse recovery and switching characteristics. In the proposed design, the conventional right-side trench channel is replaced by a Schottky diode, and a split-gate structure is connected to the source. The Schottky diode suppresses body diode conduction and eliminates the bipolar degradation effect. The split gate reduces the coupling area between the gate and drain, thereby lowering the feedback capacitance and gate charge. In addition, when the split gate is connected to a high potential, it attracts electrons to form an accumulation layer near the source, which increases electron density. During reverse conduction, the current flows through the Schottky diode, while the split gate enhances electron concentration and thus current density. The split-gate structure also shields the gate from the drain, reducing the Gate–Drain Charge (QGD) and improving switching performance. Objective Conventional Double-Trench MOSFETs (DT-MOS) typically require an external anti-parallel diode to function as a freewheeling diode in converter and inverter systems. This necessitates additional module area and increases parasitic capacitance and inductance. Utilizing the body diode as a freewheeling diode could reduce cost and save space. However, this approach presents two major challenges. First, due to the wide bandgap of SiC, the turn-on voltage of the intrinsic body diode rises significantly (approaching 3 V), which increases switching loss. This paper presents a new DT-MOS, referred to as SDT-MOS, with an integrated Schottky diode, demonstrated using TCAD SENTAURUS. In the proposed structure, the conventional right-side channel is replaced with a Schottky junction, and a source-connected split gate is embedded in the gate oxide. The SDT-MOS achieves low power consumption and reduced reverse recovery current. Methods Sentaurus TCAD is used to simulate and analyze the electrical performance of the proposed structure and its conventional counterpart. The simulation includes key physical models, such as mobility saturation under high electric fields, Auger recombination, Okuto–Crowell impact ionization, bandgap narrowing, and incomplete ionization. To improve simulation accuracy and align the results with experimental data, interface traps and fixed charges at the SiC/SiO₂ interface are also considered. Results and Discussions The Miller capacitance (Crss or C_GD) extracted at V_ds of 400 V is 29 pF/cm² for the SDT-MOS, representing a 61% reduction compared to the DT-MOS, which has a C_GD of 74 pF/cm². This reduction is primarily attributed to the integrated split-gate structure, which decreases the capacitive coupling between the gate and drain electrodes (Fig. 7). The total switching loss (Eon + Eoff) of the SDT-MOS is 1.58 mJ/cm² , which is 59.3% lower than that of the DT-MOS (3.88 mJ/cm² ), due to the improved switching characteristics enabled by the split gate (Fig. 10). In addition, the peak reverse recovery current (I_RRM) and reverse recovery charge (Q_RR) of the SDT-MOS are 165 A/cm² and 1.39 μC/cm², representing reductions of 31.3% and 54%, respectively, compared to the DT-MOS (Fig. 11). Conclusions A novel double-trench SiC MOSFET (SDT-MOS) with an integrated Schottky diode has been numerically investigated. In this structure, the right-side channel of a conventional DT-MOS is replaced with a Schottky diode, and a split gate is connected to the source. This configuration results in improved switching and reverse recovery performance. With appropriate optimization of key design parameters, the SDT-MOS retains the fundamental characteristics of a standard MOSFET. Compared with the conventional DT-MOS, the proposed device suppresses body diode conduction, mitigates bipolar degradation, and achieves a 64.9% reduction in Q_GD. Switching loss is reduced by 59.3%, and Q_RR is reduced by 54%. These enhancements make the SDT-MOS a strong candidate for high-efficiency, high–power density applications.
- Schottky diode,
- Bipolar degradation effect,
- Split gate

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References(21)

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