Researchers from the University of North Carolina, led by Jay Narayan have integrated gallium nitride with silicon as a material for electric grids.

 Despite the recent efforts for energy independence, modern energy needs are growing steadily. Viable options moving forward are reduced consumption and more efficient means of delivering energy.

In light of this, the University of North Carolina is researching how to balance an increased energy demand with a more efficient means of delivery through "smart" grids.

The smart grid is a recent development in electrical engineering, which increases current distribution efficiency compared to traditional electric grids. However, with new technology comes the need for new material.

Jay Narayan and John C. Fan have led a team of researchers for the past decade into the process of developing a way to "integrate" gallium nitride (GaN) onto silicon chips for the use of smart grids and other technologies.

GaN is a substance that can handle high voltage and current."This is an exciting material, which is needed for these high power devices directly," Narayan said. "So you can make these smart grids, which are electric grids married with a computer chip. So you can transmit power more efficiently. If there is trouble, you can sense and manipulate it, since it is on a chip. The smartness means there is something you can sense, manipulate, and respond."

Smart grids are remarkable for being able to detect levels of demand for generated current and adjust distribution accordingly, according to Narayan.

"For example, suppose parts of the region are not using or expending much energy. This grid will automatically divert energy to places where it's needed the most," Narayan said. "This is extremely valuable to sources of energy that can't be stored well, like solar. If you have a solar farm, you can't store that energy for very long. Batteries have limited capacity. So in a smart grid, this energy can be used at the point of generation—immediately."

Although storage capacity is limited, there is a large response on the industry's side to confront the problem. ABB, a multinational power technology company, has been looking into ways to improve storage technology. Despite being the leading company in the world for power technology, ABB has set up an outpost on Centennial Campus to research and enhance the present grid.

"You need the storage in order to charge up batteries when you can produce the energy, so you can use the stored energy when it's not sunny, if you're using solar energy as an example," Le Tang, the VP and Head of the U.S. Corporate Research Center for ABB, said. "We are working on the interface of the renewable sources with the power grid. They don't naturally go together."

Narayan's goal is to be able to apply his new discoveries to the industry, especially for the "smart grid." He has been working closely with technology companies like ABB, Cree and Kopin to develop the connections necessary to make an impact with his new discoveries. Nevertheless, Narayan's focus is not limited to smart grids. He is first and foremost a materials scientist, so his main concern was to figure out a way to "marry" GaN to silicon. Considering applications for these techniques came later.

Narayan employed the help of former PhD student and now current assistant professor of materials engineering Tom Rawdanowicz to progress the research process back in 2000.

"Narayan is a visionary and when he sees his students working on something, he has a knack to see something much farther down the road more often than the student does," Rawdanowicz said.

Their research consisted of achieving a "marriage" of GaN on silicon similar to prior existing integrations of GaN on sapphire chips.

"Right now, for GaN, they are using sapphire in two-inch and three-inch wafers," Narayan said. "If you could increase that to twelve inches, on silicon, that would be like an increase in a factor of 14. More efficient basically."

Moreover, GaN on silicon will be more energy efficient and cost efficient. "Silicon is just sand," Narayan laughed. "The manufacturing prices are a fraction of that of sapphire."

However, GaN does not exist in a vacuum ; "It's interesting working in the field with real world applications, especially with GaN," Rawdanowicz said.

Besides its use in smart grids, GaN can be used in various sorts of electronics, including LED lighting and high frequency communications for the military.

"The power savings, especially with regards to the environment, can save this country," Rawdanowicz said. LED lights that use this technology require less energy, last longer, and are brighter, he pointed out.

The potential for savings is so great that the government has invested a plethora of resources into the research. Narayan has received much of his funding from the National Science Foundation (NSF), which has been an important contributor to smart grid research. The NSF has poured an additional $18.5 million into the FREEDM Center on Centennial Campus, which is the center for the university's smart grid research.

Narayan stressed the importance of this new technology to the nation's economy saying, "This is also an issue of money. We get federal grants. This building here was built and maintained by the taxpayers of North Carolina. They need to see the benefits."

Many businesses have already expressed interest in utilizing GaN to various electronic needs. However, the GaN discoveries have been slow to catch on to the corporate sector, due to its novelty as well as a healthy dose of skepticism on the industry's part.

"ABB is very involved with the research and development of the smart grid, but the use for Narayan's new invention, we don't know yet," Tang said. "What I understood from him is that this is a new possibility to produce a relatively high performance sensor combination with computing power. However, we didn't get beyond that level, so we probably need to discuss more how this can be used in the smart grid."