High-Power Efficiency and Reliability: One SiC Solution

By Mouser Electronics, www.mouser, (800) 346-6873

The increased demand for smaller solar inverters and a mandate to increase the overall efficiency of white goods in China are only two of the factors driving innovation in high-voltage power semiconductors. Key to delivering this new development is the arrival of wide band-gap (WBG)-based devices that promise higher efficiency, more compact, and lighter systems. These new substrate materials can reduce up to 50% of the thermal management requirements with smaller EMI filters and inductors due to a higher operating frequency.

MOSFET case temperature in a power factor control circuit with Si and SiC diodes. (Figure courtesy of Cree)

Why is being SiC so special

Silicon carbide (SiC) is one of the new WBG substrate materials currently being used in semiconductor devices. As semiconductors get hotter, electrons begin to jump the band-gap spontaneously, and the circuit is no longer controllable. SiC materials can operate at higher voltages and in hotter and more hazardous locations.

WBG materials are also more rugged when exposed to radiation. Satellites can have less shielding. Heavy equipment requires more fuel, and the picture is clear for other applications. WBG devices will enable us to apply integrated circuits in ways and places that we could not go before.

Summary of Inverter Switching Losses.  (Table courtesy of Cree)  

Since WBG materials are also thinner, they fit in smaller locations with less packaging for the same functionality. Hazardous locations are often size restricted as well. SiC has the potential to make significant changes to the oil industry and geology-based industries in general.

A SiC sibling: Gallium nitride (GaN)

Another WBG material is gallium nitride. GaN has a wide band-gap and is less expensive. However, both SiC and Si are significantly more thermally conductive than GaN. Therefore, as these devices heat up, both give up their heat more readily to heat sinks and heat does not build up. A GaN substrate is less able to transfer heat away from itself. This affects GaN’s ability to operate at high temperatures. Nevertheless, GaN is used for other WBG properties and is applied where SiC is cost prohibitive. Of course, the overall cost of SiC in a system may outweigh the initial low-cost advantage of GaN, and technology is known to rapidly improve for the betterment of humans, especially when profit is involved. For power supplies, magnetics design, materials, and construction also greatly affect efficiency, so large gains in efficiency can still be found elsewhere. WBGs have much more to offer in terms of generating new applications and making possible the formerly impossible.

CMF10120D 1200V SiC MOSFET  (Image courtesy of Cree)

Mouser stands at the forefront of this new generation of power discrete semiconductors. Through supplier partners including Cree, Fairchild, International Rectifier, and others, Mouser offers the latest power technology to design engineers worldwide with next-day delivery of all in-stock SiC and GaN products. Visit www.mouser.com to see What’s Next in power electronics.