Silicon Carbide (SiC)

Silicon Carbide (SiC) is a wide-bandgap semiconductor used in high-voltage power MOSFETs and diodes. Its bandgap of about 3.26eV, very high critical breakdown field (roughly 2.2MV/cm), and excellent thermal conductivity (around 4.9 W/cm-K) make it well suited to the high-voltage, high-temperature sections of a power supply. Where GaN tends to dominate lower-voltage, ultra-fast switching, SiC shines at higher voltages and higher operating temperatures.

Why the wide bandgap helps

Because SiC withstands roughly ten times the electric field of silicon, the drift region of a SiC device can be about ten times thinner for the same blocking voltage. Thinner drift means lower on-resistance, faster switching, less reverse-recovery charge, and shorter dead times, all of which cut both switching and conduction losses. Commercial SiC MOSFETs span roughly 650V to 3300V ratings, covering the front-end of high-power and three-phase supplies.

Practical payoff

In server, industrial, and data-center power, replacing silicon switches with SiC can roughly halve power-stage losses, which matters when a facility runs racks of high-draw hardware around the clock. SiC also tolerates higher junction temperatures, easing the thermal design of dense converters, though the devices cost more and demand careful gate-drive design.

SiC is frequently paired with soft-switching topologies; see our entries on soft switching (ZVS/ZCS) and the LLC resonant converter for how these devices get used in real supplies.