What are the characteristics of body diode in SiC MOSET?

A body diode in a general SiC MOSFET is a SiC pn junction diode. The reverse recovery time (trr) of this pn junction diode is faster than that of a normal Si pn junction diode.

As shown in Figure 1, Toshiba’s third generation SiC MOSFET has a built-in SiC Schottky barrier diode (SBD) between SiC MOSFET’s drain and source. This reduces the inductance due to wires and circuit boards when the SBD is connected externally. Threfore Toshiba’s third generation SiC MOSFET is a suitable device for reducing the losses and noises caused by high frequency switching. In addition, the forward voltage (VF) is smaller than that of SiC MOSFET without a built-in SBD, and conduction loss can be reduced as shown in Figure 2.
Built-in SBD is also effective for improving reliability. As mentioned above, Toshiba’s SiC MOSFET has a built-in SiC SBD and is designed to be less conductive to the body diode (pn junction diode). This reduces the risk of variations in characteristics such as the forward voltage of pn junction diode (VF), the threshold voltage (Vth) and the on-resistance (RDS(ON)) of SiC MOSFET, due to crystal dfects generated during long-term operation.

Figure 1. The third generation SiC MOSFET Equivalent Circuit
Figure 1. The third generation SiC MOSFET Equivalent Circuit
Figure 2. I<sub>DR</sub>-V<sub>DS</sub> Characteristics
Figure 2. IDR-VDS Characteristics

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