Researchers at the Norwegian University of Science and Technology's (NTNU) Department of Electronic Systems, led by professors Helge Weman and Bjørn-Ove Fimland, have succeeded in building UV LEDs by growing AlGaN nanowires on graphene. "We've shown that it's possible, which is really exciting," says PhD candidate Ida Marie Høiaas, who has been working on the project with PhD candidate Andreas Liudi Mulyo.
A layer of graphene placed on glass forms the substrate for the researchers' new diode that generates UV light. Researchers then grew nanowires of AlGaN on the graphene lattice, using molecular beam epitaxy. This was conducted in Japan, where the NTNU research team collaborates with Katsumi Kishino at Sophia University in Tokyo.
After growing the sample, researchers at the NTNU NanoLab made metal contacts of gold and nickel on the graphene and nanowires. Graphene is transparent for light of all wavelengths, so the light emitted from the nanowires shines through the graphene and glass.
"We've created a new electronic component that has the potential to become a commercial product. It's non-toxic and could turn out to be cheaper, and more stable and durable than's fluorescent lamps. If we succeed in making the diodes efficient and much cheaper, it's easy to imagine this equipment becoming commonplace in people's homes. That would increase the market potential considerably," Høiaas says.
Concurrently with her research at NTNU, Høiaas is working with the same technology on an industrial platform for CrayoNano. The company is a spinoff from NTNU's nano research group.
UVC LEDs that can replace fluorescent bulbs are already on the market, but CrayoNano's goal is to create far more energy-efficient and cheaper devices.
Høiaas believes that a lot of improvements are needed before the process developed at NTNU can be scaled up to industrial production level. Necessary upgrades include conductivity and energy efficiency, more advanced nanowire structures and shorter wavelengths to create UVC light.
CrayoNano has progressed further, but their results have not yet been published.
"CrayoNano's goal is to commercialize the technology sometime in 2022," says Høiaas.