U of A researchers improve sensing for fusion energy, space science
Materials scientist Zafer Mutlu’s study proves graphene nanoribbons send electrical signals in harsh conditions.
University of Arizona Provost Postdoctoral Fellow Ali Habiboglu synthesizes graphene nanoribbons – a material Zafer Mutlu and collaborators are investigating to withstand and sense radiation in devices and electronics.
Graphene nanoribbons – tiny strips of carbon material that withstand extreme environments – could help researchers track radiation in fusion reactors and deep space technology.
University of Arizona researchers integrated graphene nanoribbons, or GNRs, into semiconductor devices and exposed them to intense radiation. The ribbons' atomic framework stayed intact while still producing a measurable electrical response. This result suggests the ribbons could serve as radiation sensors in extreme environments, such as a fusion reactor, where radiation levels run high.
"The devices survive the exposure and still respond, but their electrical performance changes dramatically," said principal investigator Zafer Mutlu, assistant professor of materials science and engineering. "That's exactly the behavior we want from a sensor."
These GNR-enhanced sensors could help engineers monitor conditions inside a fusion reactor. Fusion power generates electricity when light nuclei merge into a single heavier nucleus, releasing a massive amount of energy. The process requires little fuel to produce that energy, so it could serve as a limitless source of clean power.
Because GNR sensors are more resilient than today's silicon-based sensors, they can operate closer to the reactor core. That could reduce costly shutdowns for inspection and maintenance and increase the time fusion power plants stay in operation.
"Real-time monitoring is our vision for this project," Mutlu said.
Similarly, these sensors could detect early signs of radiation damage in space systems like satellites.
Pushing materials design at the nanoscale
For the proof-of-concept study, published in the journal ACS Applied Materials and Interfaces, researchers synthesized GNRs at the molecular level, then embedded them in common semiconductor devices. They used emerging fabrication techniques Mutlu helped develop to make the ribbons exactly nine atoms wide and one atom thick – tens of thousands of times thinner than a human hair.
The next step for Mutlu and his collaborators is to test the same device under different radiation doses. They also plan to explore GNRs of different sizes. After those investigations, Mutlu is confident the synthesis method used in the study will allow researchers to customize more ribbons.
"You can design the material atom by atom, molecule by molecule. You can make it less sensitive, more sensitive, non-sensitive," said Mutlu, whose research has focused on quantum materials and semiconductor devices for more than a decade.
U of A researchers are also collaborating with industry on efforts to scale these enabling technologies and deliver fusion power to the electrical grid.
Mutlu and eight other U of A researchers published this proof-of-concept study. Mutlu's group carried out the nanoribbon synthesis, device fabrication and electrical characterization, and the gamma irradiation experiments were led by MSE professor Barrett G. Potter and University Distinguished Outreach Professor Kelly Simmons-Potter of electrical and computer engineering.
Co-authors included postdoctoral researcher Kentaro Yumigeta and doctoral student Muhammed Yusufoglu, both of whom work in the Department of Materials Science and Engineering.
