A Low-Loss 1.2 kV SiC MOSFET with Improved UIS Performance

Area of Science:

• Materials Science
• Electrical Engineering
• Semiconductor Physics

Background:

• Silicon carbide (SiC) MOSFETs are crucial for high-power applications due to their superior properties.
• Traditional SiC MOSFETs face challenges like bipolar degradation of the body diode and significant switching losses.
• Improving avalanche stability and reducing on-resistance are key objectives for advanced SiC power devices.

Purpose of the Study:

• To propose and analyze a 1.2-kV-rated double-trench 4H-SiC MOSFET with an integrated low-barrier diode (DT-LBDMOS).
• To demonstrate the elimination of body diode bipolar degradation and reduction in switching losses.
• To enhance avalanche stability and improve overall device performance metrics.

Main Methods:

• Numerical simulations were employed to verify the device physics and electron transport mechanisms.
• The proposed DT-LBDMOS was compared against the gate p-shield trench 4H-SiC MOSFET (GPMOS).
• Key performance parameters including reverse on-voltage, reverse recovery charge, gate-to-drain capacitance, switching losses, and on-resistance were evaluated.
• Unclamped inductive switching (UIS) tests were conducted to assess avalanche energy and stability.

Main Results:

• The integrated low-barrier diode (LBD) creates an easier electron transfer path, eliminating body diode bipolar degradation.
• Compared to GPMOS, DT-LBDMOS exhibits a 37.8% lower reverse on-voltage (1.54 V vs. 2.46 V).
• Significant reductions were observed in reverse recovery charge (28%), gate-to-drain capacitance (76%), turn-on loss (52%), and turn-off loss (35%).
• Specific on-resistance decreased by 34% due to weakened interface state scattering, improving both HF-FOM and P-FOM.
• Enhanced avalanche energy and stability were confirmed through UIS testing.

Conclusions:

• The proposed DT-LBDMOS effectively overcomes the bipolar degradation issue in SiC MOSFETs.
• The integrated LBD significantly enhances device performance, including lower losses and improved stability.
• DT-LBDMOS demonstrates considerable potential for practical applications in high-performance power electronics.