Manipulating graphene for transistor applications

Scientists at the US Department of Energy’s Ames Laboratory have come one step closer to manipulating the electronic structure of graphene, which may enable the fabrication of graphene transistors that would be faster and more reliable than existing silicon-based transistors.

Graphene, a two-dimensional layer of carbon, has been extensively studied since it was first produced in 2004 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.

Now, the Ames researchers have used density functional theory calculations to predict the configurations necessary in order to modify graphene’s electronic band structure with metal atoms. Their breakthrough has been published in the journal Carbon.

“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 in the laboratory. “Our calculations guided the placement so that we can manipulate these quantum properties to behave the way we want them to.”

The team’s work will guide experimentally the use of the effect in layers of graphene with rare-earth metal ions ‘sandwiched’ (or intercalated) between graphene and its silicon carbide substrate. Because the metal atoms are magnetic, the additions can also modify the use of graphene for spintronics.

“We are discovering new and more useful versions of graphene,” said Ames Laboratory Senior Scientist Michael C 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.”