A UT Dallas graduate student’s surprising research results could ultimately lead to high-performance nanoelectronics applications such as electron emitters, thermal-infrared night-vision sensors and solar absorbers for harvesting sunlight.
Materials science graduate student Muge Acik has been working with graphene, a single sheet of carbon that exhibits unique electronic and mechanical properties, making it a candidate to eventually replace silicon in applications like ultrafast transistors.
Making real-world devices from graphene, however, depends upon controlling the edges of graphene sheets, which often dictate the material’s electronic properties. Simply adding oxygen atoms at the edges may turn graphene into an insulator.
Performing her experimental work on graphene oxide (GO) in Dr. Yves Chabal’s Laboratory for Surface and Nanostructure Modification, Acik discovered a new infrared absorption mechanism when GO is annealed to about 850°C to remove most oxygen. The result was a very special arrangement of oxygen atoms at the edges. This stable configuration fosters the electronic conduction or emission necessary for device operation and for electron emitters.
Moreover, “this new phenomenon opens the door to tailoring giant infrared absorption at different spectral positions by modifying the nature of the edge termination,” she and her co-investigators concluded. And that opens the door to employing graphene in a number of nanoelectronic applications in which infrared absorption is important, such as night-vision sensors and sunlight-harvesting solar absorbers.
“This work is a good example where the contribution from theory has been critical, as provided by Dr. G. Lee, a postdoctoral fellow working under the supervision of Dr. Kyeongjae ‘KJ’ Cho,” said Chabal, head of materials science and engineering and holder of the Texas Instruments Distinguished University Chair in Nanoelectronics. “The theory provided a detailed understanding of this new phenomenon that would have remained puzzling on its own.”
Cho added that “this experimental finding is consistent with an earlier theoretical prediction of the metallic state of graphene edge oxide published in Physical Review in 2009.”
The team’s results recently appeared in the journal Nature Materials in an article titled “Unusual Infrared Absorption Mechanism in Thermally Reduced Graphene Oxide.”
This absorption is a new phenomenon that’s unique to graphene, according to Chabal in an article that appeared in nanotechweb.org, noting that the potential applications are very exciting.
“The effect cannot be explained by simple infrared absorption mechanisms and can only happen if free, mobile electrons are induced in reduced graphene oxide – something that has never been observed before,” the article concluded.
The research was funded by the Semiconductor Research Corp.’s Nanotechnology Research Initiative and by Texas Instruments. The work was done in collaboration with Cecilia Mattevi and Manish Chhowalla at Rutgers University. A synopsis of the Nature Materials article is featured under Nano Focus here.