How wide is your bandgap?

Image courtesy Zephyris via Wikipedia Commons

A new consortium of universities, corporate research centers and government agencies takes aim at commercializing a potentially game-changing technology.

On Wednesday, January 15th, President Obama visited the campus of North Carolina State University to announce the creation of a new Manufacturing Innovation Institute. The consortium will be focused on a advancing a technology known as wide bandgap or “WBG” semiconductors.

Now, ABB is about as engineering-friendly an environment that you’ll find outside of, well, an institute studying something called wide bandgap semiconductors.  But even here many of us here were looking to our degree-laden colleagues asking, “wide what?”

So, what exactly are wide bandgap semiconductors?

Let’s start with the last term: semiconductors.  These are materials that conduct electricity better than insulators like glass but not as well as conductors like copper or aluminum. They are used in more applications than you can possibly imagine.

OK, now for the hard one. “Bandgap” refers to a kind of threshold measurement, namely the amount of energy it takes to make a semiconductor start to conduct electricity. Silicon, for example, has a bandgap of 1.1 eV whereas Silicon Carbide has a bandgap of 3.3 eV.

What this means is that a semiconductor made out of SiC is capable of handling much higher voltage levels that the one made out of plain Si.  That, in turn, means it can operate at higher temperatures with less resistance and lower losses. WBG semiconductors are also capable of switching faster than conventional semiconductors.

In practical terms, WBG technology allows semiconductor devices to be made smaller and perform better while operating more efficiently than they do today.

To take one example, inverters used to convert the DC power produced by solar panels to the AC used by the grid typically are around 96 percent efficient (i.e., 4 percent of the energy passing through the device is lost). An inverter made with WBG semiconductors is around 99 percent efficient. That may not seem like a big difference, but when you multiply a 3 percentage point gain across hundreds of megawatts flowing out of utility-scale solar plants, it really adds up.

Of course, there’s a catch. WBG semiconductors are presently very expensive to manufacture. They are also not always capable of replacing conventional semiconductors in certain applications. These challenges will need to be overcome, but that’s precisely the raison d’étre of the Manufacturing Innovation Institute.

Should WBG reach commercial viability, its potential is staggering. The US Department of Energy estimates its share of the global lighting sector alone could reach $84 billion by 2020. Now that’s what I call a disruptive technology.


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About the author

Bob Fesmire

Bob Fesmire is a Content Manager at ABB, based in Cary, North Carolina. He has written more than 150 articles and white papers on a variety of topics including energy efficiency, industrial automation and big data. In addition to his work at ABB, Bob is also the co-author of Energy Explained, a non-technical introduction to all aspects of the energy industry.
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