Traditional power electronic converters using Si-based power devices will not be able to satisfy the increasing demands for higher efficiency, control bandwidth, power density, and switching frequency.
Higher switching frequencies, leading to smaller magnetics and higher operating temperatures, are useful especially in harsh industrial applications.
When we compare Si to GaN and SiC, we find some distinctive properties that allow these devices to operate at lower leakage currents and higher voltages. It is a fact that a higher operational frequency can be achieved through an increase in the electron mobility and electron saturation velocity. Compared to Si devices, WBG semiconductors have a lower intrinsic carrier concentration (10–35 orders of magnitude), higher thermal conductivity (3–13 times), higher electric breakdown field (4–20 times), and larger saturation velocity (2–2.5 times).
SiC also has higher electron mobility than Si and GaN exhibits a higher electron mobility than both Si and SiC. This means that GaN delivers the best performance at very high frequencies. It is predicted that the total price gap between SiC/GaN and Si will continue to steadily decrease. It is also projected that GaN will offer a better result over SiC and even Si in terms of the added cost in the highest switching frequency applications
Let’s look at thermal conductivity which represents another crucial factor: the higher the thermal conductivity, the more efficient the heat conduction properties. SiC exhibits a higher thermal conductivity than either GaN or Si; so SiC devices are theoretically able to operate at higher power densities than both GaN and Si devices. In summary, the higher thermal conductivity, wider bandgap, and higher breakdown field give SiC semiconductors the edge over other semiconductor devices in high-power applications.
In conclusion, SiC and GaN discrete devices are moving into higher content modules which lower cost, reduce size, and improve performance. WBG devices have made a significant strides in replacing Si, offering the benefits of reduced switching losses, lower cooling volume, and reduced thermal solutions cost.