There is an overlap between SiC and GaN at rated voltages between 600 V and 750 V, but at lower voltages than that only GaN devices are used and at higher voltages than that only SiC devices are used.

Even at 650 V where there are available both GaN and SiC devices, there is little direct competition between them. For such voltages, SiC devices are used for controlling greater powers, where also the power dissipated by the device is great enough to require a big package that enables efficient cooling, while the pure GaN devices (i.e. not the hybrid silicon-GaN cascode transistors) are available only in small surface mounted packages, which enable much higher switching frequencies, but at lower output powers, because it is more difficult to cool them well enough.

For now, the SiC devices are only unipolar devices, i.e. MOSFETs and Schottky diodes. But in the future, when SiC crystals with fewer defects will become available, there will also be SiC bipolar devices, i.e. thyristors and IGBTs. The bipolar devices will be available for much greater powers than the current devices, while also being much faster than the silicon bipolar devices. On GaN, bipolar devices are not possible, so GaN will always be used only for higher switching frequencies, but lower output powers than SiC.

Silicon carbide MOSFETs are the best devices for the SOTA electric vehicles and also for their chargers, which work at 800 V (where 1200 V SiC MOSFETs are used) or at 1000 V (where 1400 V SiC MOSFETs are used).