Materials Engineering and the 'science of stuff'

Posted: December 20, 2017

Left to right: Subrina Rafique, Md Rezaul Karim, Hongping Zhao and Zixuan Feng.
Advanced semiconductor materials, found nowhere in nature, are being created in labs at The Ohio State University. Nationally, the work is respected for continually enhancing the efficiency and functionality of anything from cell phones to space shuttles.

As one of the newest faculty members in the Department of Electrical and Computer Engineering (ECE) at Ohio State, Associate Professor Hongping Zhao specializes in such materials research.

Technological devices are all made from some form (or combination) of metals, ceramics, semiconductors, polymers or even biomaterials, each advancing the capabilities of science daily. In its most basic explanation, the study of materials is often called the "science of stuff." 

Zhao said Ohio State is an excellent place for her to maximize her potential and make the greatest contributions to the field of semiconductor materials science and device technologies, as it's one of the top five universities currently advancing the field.

“I was very impressed with the research infrastructure, as well as Ohio State’s focus and strengths in semiconductor materials and devices,” Zhao said.

Institute for Materials Research Director and ECE Professor Steven Ringel made it his mission a decade ago to make Ohio State a leader in materials science.

Zhao said facilities such as Nanotech West, the Center for Electron Microscopy and Analysis (CEMAS), the Clean Room (SEAL), and the university’s commitment toward establishing the metal organic chemical vapor deposition (MOCVD) capability for wide bandgap semiconductors ultimately convinced her Ohio State was where to begin the next phase of her career.

“We need a lot of infrastructure and facilities support, and Ohio State is well-established with that,” Zhao said.

Her team works on advancing semiconductor material growth, with the goal of exploring fundamental materials science and attaining high-quality novel structures with well-controlled properties for device applications.

“Device performance, to a large extent, depends upon your material quality,” Zhao said. “It usually takes a tremendous amount of effort and time to fully understand these materials and their basic properties. Once we have a better understanding, we have better control.”

Decades ago, she said, Thomas Edison had a breakthrough when he invented lightbulbs.

“Today, LED-based solid state lighting technology advanced this application away from tungsten and filaments,” she said. “Nowadays, we don’t use that. We use a chip of semiconductor materials. We apply voltage across the semiconductor to produce light in a much more efficient way.”

Such advancements, she said, allowed many cities to replace traditional street lighting technology infrastructure with LED, resulting in greater efficiency, energy, and annual electricity cost savings.

“We are still working on research to improve LED efficiency, to lower the price even further,” she said. “For example, our recent installation of the nitride MOCVD system at Ohio State will allow us to explore novel materials and structures for high efficiency LEDs, especially those emitting beyond blue and green. LEDs also apply broadly in the automotive industry, serving as the backlight for computer screens. You may not even notice, but there are so many implementations in our daily lives from LED technology."

As a young Chinese student, how did Zhao ultimately decide to focus on something so scientifically specific?

“My background was in physics. I was always interested in physics and mathematics since I was young. I always wanted to pursue my career in research and education,” Zhao said.

Ultimately, she wanted to learn more about how physics applied to engineering and technology, going on to earn her MS degree in electrical engineering.

Upon graduation, she went on to pursue a PhD in the United States, allowing her to perform cutting edge research in the MOCVD growth of III-nitride materials and nanostructure engineering for high efficiency LEDs. The experience convinced her toward a career in academia.

“Right now we are working on a very emerging ultra-wide band gap semiconductor, Gallium Oxide. We use a different approach to develop the growth of this semiconductor, to study its fundamental material properties and their device applications,” she said. “This ultra-wide band gap material recently attracted a lot of interest due to its promising application toward high-power electronics. (These) devices can be widely used in your computer adapter or adapters in your cell phones, appliances at home, as well as anything from electrical cars, to high-powered grid applications. All of these impact energy efficiencies significantly.”

Being associated with the Materials and Manufacturing for Sustainability (M&MS) Discovery Theme also expanded her collaborations with faculty across campus. While only recently hired, Zhao is already working on solid state technology with Ringel, as well as fellow colleagues Siddharth Rajan and Jinwoo Hwang, and professors Sanjay Krishna, Len Brillson, and Roberto Meyers.

“There are so many opportunities to work with our colleagues here,” she said. “Not only in our department, but more broadly across the campus.”

Article by: Ryan Horns, PR Coordinator