Air Force award supports research on electronics that can survive extremes

UNIVERSITY PARK, Pa. — Betul Akkopru-Akgun, assistant research professor in Penn State's Department of Materials Science and Engineering and the Materials Research Institute, has received an Air Force Office of Scientific Research Young Investigator Program award to investigate how electricity and heat move through materials used in extreme environments.

When extreme-environment electronics fail in harsh operating conditions, the cause is often not a single flaw or design issue. Instead, failure can emerge from complex interactions among heat, electrical charge, defects, and interfaces within the material. Understanding those interactions is the focus of Akkopru-Akgun's research.

The Air Force Office of Scientific Research's Young Investigator Program is a highly competitive initiative that supports early-career researchers pursuing fundamental scientific questions with long-term technological impact.

For Akkopru-Akgun, however, the recognition is less about the award itself and more about the scientific questions it will help answer.

Her project focuses on polar nitride materials, a class of materials that can operate at high frequencies and withstand harsh conditions, including high temperatures and radiation exposure. These materials, which include aluminum nitride and aluminum scandium nitride, are increasingly important for technologies such as communications systems, sensors, radar platforms and precision timing devices.

“What excites me most is that we still do not fully understand why these materials lose energy, generate heat or gradually change their behavior over time, especially in harsh environments,” Akkopru-Akgun said. “By uncovering the underlying mechanisms, we can develop a deeper understanding of how to design electronic materials that are more stable, efficient and reliable.”

At the center of her research is a deceptively simple question: How do electricity and heat move through materials under extreme operating conditions?

The answer could have major implications for the performance and reliability of next-generation electronics, she said. Inside these materials, tiny defects, interfaces and internal electric fields can influence the movement of both electrical charges and vibrations known as phonons, which carry heat. Scientists know these factors affect device performance, but they do not yet fully understand how they interact with one another.

"What we still do not fully understand is how defects, interfaces and domain structures interact with the strong internal electric fields generated by polar nitrides to control energy loss, self-heating and long-term drift,” Akkopru-Akgun said. “Those processes are strongly coupled because the same defects that affect electrical transport can also scatter phonons and reduce thermal transport.”

Her research aims to directly control the internal electric fields generated by polarization and measure how both electrical and thermal behavior respond.

“Can we actively control which processes dominate how electrical charges and heat move through a material?” she said. “If we can understand how they work together, we could develop a predictive framework for designing electronic materials that are more efficient, stable and reliable in extreme environments.”

The work builds on a research career focused on understanding how defects, interfaces and other microscopic mechanisms affect the reliability of electronic materials. Akkopru-Akgun has previously developed physical models that explain how these factors influence charge transport — the way electrical charges move through a material — and device lifetime in ferroelectric films, which are very thin layers of materials that can hold and switch an internal electric polarization. This makes them useful in memory, sensors and other electronic devices. Her findings have helped improve the durability of piezoelectric microelectromechanical systems, or piezoMEMS, which are tiny devices that use electrical signals to create motion or sense movement.

The new project expands that expertise into a growing area of materials science focused on understanding how charge and heat transport emerge from interactions among defects, interfaces and polarization fields in extreme environments.

“Materials like aluminum nitride and aluminum scandium nitride are attractive because they remain stable under high-temperature, high-power and radiation conditions while also supporting strong electromechanical functionality,” Akkopru-Akgun said. “Understanding how these materials behave at a fundamental level will help unlock their full potential for future aerospace and defense applications.”

The project also will create new opportunities for students at Penn State, she said. Researchers in her lab will gain experience in materials synthesis, advanced characterization techniques, charge transport measurements and thermal analysis while working on problems that bridge fundamental science and real-world technological challenges.

“I think that combination of basic science and application relevance is especially valuable for training the next generation of researchers,” Akkopru-Akgun said.

Ultimately, the significance of the work extends beyond any single device or application. By revealing how energy moves and dissipates inside materials, designed for extreme-environments, Akkopru-Akgun said she hopes to provide the scientific foundation needed for a new generation of electronics that can perform reliably in demanding thermal, electrical and radiation environments.