The founders of Cree, Inc. started a company based on the potential of silicon carbide, a finicky but promising compound long employed as an abrasive but with the potential for much more.
Used since the 1800s for sandpaper and grinding wheels and as a hard and durable ceramic for automotive brake pads or turbine blades, silicon carbide is also a semiconductor that is particularly well suited for efficiency at high operating temperatures.
“That’s what it was born from the stars for,” said John Edmond, a Cree co-founder and NC State materials science and engineering alumnus. “As a power electronic semiconductor.”
Cree is now Wolfspeed, Inc. and the focus has shifted from using silicon carbide to make LED lights to using it to make semiconductor wafers for power electronic devices. In 2022, Wolfspeed announced plans to build a manufacturing campus in Chatham County, about 50 miles west of NC State. The company intends to invest $5 billion and create 1,800 new jobs by 2030. It will be the largest silicon carbide materials production facility in the world and represents the largest economic development project in North Carolina’s history.
The company feels strongly that silicon carbide, which it has 36 years of experience working with, will soon power everything from electric vehicles and fast chargers for them to 5G wireless infrastructure and renewable energy capture and storage.
“It’s going to be the next power semiconductor,” Edmond said. “We are going to replace all silicon power with silicon carbide. And the industry knows it.”
It all started in a laboratory in the Department of Materials Science and Engineering (MSE) at NC State.
Beyond the lights
Cree was founded in 1987 by Edmond, John Palmour, Neal Hunter, Thomas Coleman, Calvin Carter and Eric Hunter. Five of the six were MSE alumni.
The company was born out of the lab of Robert Davis, now an emeritus professor in MSE. Davis had begun work with silicon carbide as a semiconductor and had received funding from the Office of Naval Research to study it for microwave applications. The Cree founders worked on different aspects of silicon carbide for their Ph.D. and master’s degrees — and, in Carter’s case, as a postdoctoral scholar helping run Davis’ lab — but were collaborating every day. Those roles would carry through when they started the company.
Cree was founded over lunch at a restaurant on Hillsborough Street next to campus. Neal Hunter and Eric Hunter maxed out their credit cards and Neal took out a second mortgage so that they could hire Edmond as the first employee.
At the time, LED lights were the most commercially viable end-use product for the work that the founders had done at NC State. Blue LED lights were not being produced to the extent that red and green ones were (combine those three and you could create a full-color LED display). Cree saw an opportunity to produce blue lights with silicon carbide, and later with gallium nitride on a silicon carbide substrate.
The years of success as an LED-lighting company gave Cree valuable experience with creating silicon carbide crystals and wafers, an intensive process because the material wants to form at one of 200 different structures and there’s only one that you want. The payoff, though, is significant: silicon carbide and gallium nitride, so-called wide bandgap semiconductors, are 10 to 15 percent more efficient than current silicon semiconductors.
As lighting became more of a commodity, the company began to shift its focus to high-power semiconductor devices. Wolfspeed has now sold off its LED and microwave businesses to focus exclusively on these devices.
“This world is going electric, and silicon carbide for anything over 100 volts saves you energy,” Carter said. “It can handle a lot more power in the same area than silicon can, so it keeps things small and light. That’s a big deal.”
Close to home
The company and its founders have maintained their ties to the University, including with a name that’s a nod to the NC State Wolfpack.
NC State’s strength in research on wide bandgap devices, including collaborations with Wolfspeed, helped the University land the lead role in the PowerAmerica National Manufacturing Innovation Institute in 2014. Now, Wolfspeed is one of six companies partnering in a $39.4 million Department of Defense regional innovation hub led by NC State. The hub, Commercial Leap Ahead for Wide Bandgap Semiconductors (CLAWS) is funded by the federal CHIPS Act and is focused on wide bandgap devices.
When the company made the decision to build the materials facility in Chatham County, proximity to NC State’s research and workforce was one of many reasons that staying close to home made sense.
And several of the Cree founders have stayed connected to the College and NC State, giving their time and making philanthropic gifts to support scholarships and fellowships.
“NC State, that’s a special place,” said Edmond. “It’s very near and dear to my and all the founders’ hearts.”
This post was originally published in College of Engineering News.