Rare earth metals can tune graphene’s electronic properties

Scientists at the US Department of Energy's Ames Laboratory have successfully manipulated the electronic structure of graphene. As they report in a paper in Carbon, this could allow the fabrication of graphene transistors, which would be faster and more reliable than existing silicon-based transistors.

The researchers were able to calculate theoretically the mechanism by which graphene's electronic band structure could be modified with rare earth metal atoms such as ytterbium and dysprosium. This work will experimentally guide the use of the effect in layers of graphene with rare earth metal ions ‘sandwiched’ (or intercalated) between them and a silicon carbide substrate. Because the metal atoms are magnetic, they could even allow graphene to be used for spintronics, where digital information is encoded in electron spins.

"We are discovering new and more useful versions of graphene," said Ames Laboratory senior scientist Michael Tringides. "We found that the placement of the rare earth metals below graphene, and precisely where they are located, in the layers between graphene and its substrate, is critical to manipulating the bands and tune the band gap."

"We found that the placement of the rare earth metals below graphene, and precisely where they are located, in the layers between graphene and its substrate, is critical to manipulating the bands and tune the band gap."Michael Tringides, Ames Laboratory

Graphene, a two-dimensional layer of carbon, has been extensively studied by researchers everywhere since it was first produced in 2004. One reason for this is because electrons travel much faster along its surface, making it an ideal potential material for future electronic technologies. But the inability to control or tune graphene's unique properties has been an obstacle to its application.

The scientists used Density Functional Theory calculations to predict the configurations necessary to demonstrate control of the band gap structure. "Ames Laboratory is very good at synthesis of materials, and we use theory to precisely determine how to modify the metal atoms," said Minsung Kim, a postdoctoral research associate. "Our calculations guided the placement so that we can manipulate these quantum properties to behave the way we want them to."

This story is adapted from material from Ames Laboratory, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.