At the intersection of future semiconductor technologies and the reduction of greenhouse gasses emitted by the U.S. power grid is research from four electrical and computer engineers at Virginia Tech.

Principal investigator Yuhao Zhang and three other professors from the Bradley Department of Electrical and Computer Engineering have been awarded a $1.5 million grant from the National Science Foundation’s Electrical, Communications and Cyber Systems flagship program, ASCENT.

Otherwise known as Addressing Systems Challenges through Engineering Teams, ASCENT is focused on future semiconductor technologies. Zhang and his team are proposing a first-of-its-kind semiconductor technology that is optically driven for use in grid power electronics.

Key collaborators in this project include faculty from the Center for Power Electronics Systems (CPES) in Arlington and Blacksburg and the Center for Photonics Technology (CPT). Both of these research centers are based at Virginia Tech and are world leaders in their areas of focus.

CPES Lab in Blacksburg, VA. Computer screens and desks in a line
The Center for Power Electronics Systems Lab in Blacksburg. Photo courtesy of Howell Creative Group.

Working with Zhang, an expert in the areas of power electronics, micro/nano-electronic devices, and advanced semiconductor materials, are Assistant Professors Dong Dong and Christina DiMarino and Associate Professor Xiaoting Jia.

Dong is a Center for Power Electronics Systems faculty member with research expertise in power electronics and power conversion systems. DiMarino is also a member of that's center's faculty and has expertise in power electronics packaging. Jia is a Center for Photonics Technology faculty member with a background in fiber-based neural interfaces, nano-bio interfaces, and fiber sensors and devices.

The current U.S. power grid relies primarily on coal and natural gas to produce electricity. Furthermore, electricity generation is responsible for about 25 percent of greenhouse gas emissions. In an effort to reduce this environmental impact, the team will leverage the unique electronic and optical properties of ultra-wide-bandgap semiconductors, materials that can withstand a very high electric field.

Semiconductor devices within the power grid can be thought of as “switches” that turn on and off. When a switch is turned on, it allows power to flow. When it is off, it blocks the power current. These on and off “switches'' are important for the power grid because they dictate when power flow should and should not occur.

Most of today’s power switches are electrically driven, meaning they rely on the base drive current or the gate-drive voltage to turn the device on and off. As more renewable energies and higher power levels have been introduced into the grid structure, the high switching frequency needed has increased the risk of “noise.” In addition, stacking hundreds of devices to enhance power means it is difficult for them to be driven synchronously.

DiMarino explained the current setbacks of semiconductors and the potential for optically driven devices. She said advanced devices can transition on and off very quickly, which generates noise that can cause the devices to turn on when they should be off, also known as false triggering. This can cause problems such as short circuits. Further, when multiple devices are operated together, nonsynchronous driving can occur, resulting in some devices turning on before others and therefore being overstressed. Optically driving devices can significantly reduce and potentially eliminate these challenges, enabling simpler and smaller converters that can be used in the grid.

Optically driven semiconductors operate on the principle of photo-generation, using a light source from a laser fiber to turn the switch on and off. This approach provides more noise immunity because photons, or light, are being used instead of electrons. The fast speed of light allows for an ideal synchronization for driving hundreds of devices, and the number of required electrical components can be reduced.

Implementing these devices into the semiconductor power grid would drastically simplify the complexity of grid scale power, resulting in greatly improved scalability, efficiency, interactivity, and resiliency.

Zhang recently published a review on the field of power semiconductors and power electronics in Nature Electronics in collaboration with faculty from the University of Cambridge and the University of Southern California.

“The power semiconductor market has reached $40 billion and is forecasted to more than double that amount by the year 2030,” said Zhang. “Innovation in power semiconductors is a driver for energy savings in data centers, electric vehicles, and the electric grid. Therefore, it holds the key for realizing the unprecedented cuts in carbon dioxide for a greener and more sustainable environment.”

Zhang noted the strength of the electrical and computer engineering department and the quality of researchers available for innovative projects like this one.

“Our department is very diverse and transdisciplinary,” said Zhang. “One unique thing about the department is that we are not just collaborating with individuals but also collaborating with different centers — in this case, CPES and CPT. These research centers add another opportunity to strengthen the bond.”

Each team member will contribute to different areas of the project at different stages throughout the four-year timeline. Zhang, Jia, and Dong are all National Science Foundation CAREER Award winners and provide strong knowledge in their respective fields. DiMarino has received the Virginia Tech College of Engineering Outstanding New Assistant Professor Award and the DOE ARPA-E OPEN 2021 Award.

Christina DiMarino works on electronics packaging in the CPES Lab in Arlington, VA.
Christina DiMarino works on electronics packaging in the Center for Power Electronics Systems lab in Arlington. Photo by Anthony Wright for Virginia Tech.

As part of the ASCENT grant, the team will provide educational opportunities to train future engineers in the areas of semiconductor technologies, optical systems, power electronics, and microelectronics. The researchers will partner with a team in electrical and computer engineering’s Major Design Experience, a two-semester senior design project course that gives students industry-like experience.

The team members also will add project-related curriculum to their current undergraduate and graduate courses. With additional access to Center for Power Electronics Systems resources, students will have real-world learning experiences while interacting with industry professionals.

Zhang's students working on semiconductor wafers in the lab
One of Yuhao Zhang's students measures semiconductor devices that were fabricated in the clean room. Photo courtesy of Uncork-it!

The researchers also plan to collaborate with the Center for the Enhancement of Engineering Diversity at Virginia Tech to introduce semiconductor, power electronics, and nanotechnology to students, particularly middle school and high school girls. The resulting summer camps will provide hands-on experiences of the new technologies.

Zhang is hopeful for the future of the grid based on the research being done, the technology being developed, and the training being provided to students — all focused in the area of semiconductors.

“The advancements we are going to develop are for the next generation of power electronics,” said Zhang. “If successful, the hope is that in 10 to 20 years, we can have these devices built into the system.”

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