What kind of material SiC is? And what kind of characteristics does SiC MOSFET have?

SiC (silicon carbide) is a compound semiconductor material that consists of Si (silicon) and C (carbon) atoms with the densest tetrahedral arrangement.

Each atom is surrounded by four different atoms in the form of a regular tetrahedron. SiC has many crystalline structures called polytypes that exhibit different physical properties because of periodic differences in the overlap of tetrahedrons.
Compared to Si, SiC has a wider energy gap of the forbidden band (band gap) where no electron states between the valence band (an energy band filled with valence electrons) and the conduction band (an empty energy band in which electrons can exist), and the chemical bonds among atoms are strong, resulting in a higher electric breakdown field strength. SiC has about 10 times higher breakdown field strength than that of Si and can realize a power device with high withstand voltage and low voltage drop. If the withstand voltage is the same, the on-resistance per unit area can be reduced compared to Si.
While Si MOSFET is generally only commercialized up to 1000V level, SiC MOSFET is commercialized up to 3300V level because it can suppress on-resistance even at high withstand voltages. SiC can realize MOSFET, the unipolar device that operates only with electrons even in high voltage products. Because tail current is not generated, turn-off loss is reduced compared to bipolar devices. Therefore, SiC MOSFET can operate in the high switching frequency range, which was difficult with Si IGBT, and it also has the great advantage of contributing to the miniaturization of passive components such as transformers. It is suitable for power conversion applications requiring miniaturization and low loss.
SiC products offer lower on-resistance in the high voltage range and lower power loss due to high-speed switching compared to commonly used Si products. Because of its capability to operate at high temperatures, it is expected to expand among power devices that are expected to grow.
For example, as shown in Figure 1, it is widely used in electric railways, PV inverters and EV power supply equipment.

Figure 1. Power devices and applications
Figure 1. Power devices and applications

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