Huan Wu
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1
This article compares and evaluates the single pulse short-circuit robustness of silicon carbide (SiC) MOSFETs with linear and hexagonal cell topologies under different gate voltages, bus voltages, and case temperatures. The short-circuit failure mechanisms of the linear and hexagonal cell topologies are studied. A new switching model for gate failure and thermal runaway short-circuit failure modes is proposed and analyzed. The robustness performance of the linear and hexagonal cell topologies is compared and evaluated under the same short-circuit power for the first time, fully revealing the comprehensive impact mechanism of cell topologies on the short-circuit robustness for SiC MOSFETs.
A novel 4H-SiC Multiple Stepped SGT MOSFET (MSGT-MOSFET) is presented and investigated utilizing TCAD simulations in this paper. We have quantitatively studied the characteristics of the device through simulation modeling and physical model calculations, and comparatively analyzed the performance and application prospects of this novel device. The gate-to-drain capacitance (Cgd) and gate-to-drain charge (Qgd) of the MSGT-MOSFET are significantly reduced in comparison with the double trench MOSFET (DT-MOSFET) and the conventional SGT MOSFET (CSGT-MOSFET), due to the reduction of the overlapping area of the split gate (SG) structure and drift region. Therefore, the obtained high frequency figure of merit (HF-FOM) defined as [Ron × Cgd] reduced by 23.9% compared with DT-MOSFET and CSGT-MOSFET. And the HF-FOM [Ron × Qgd] for the MSGT-MOSFET significantly decreased by 71% and 50%, respectively, compared to that of the DT-MOSFET and CSGT-MOSFET. Furthermore, the switching loss is also simulated and calculated. And the total switching loss of the proposed MSGT-MOSFET realizes 42.9% and 21.7% reduction in comparison with the DT-MOSFET and CSGT-MOSFET. The overall enhanced performances suggest that the MSGT-MOSFET is an excellent choice for high frequency power electronic applications.