Researchers at the Department of Energy’s Oak Ridge National Laboratory and the University of Tennessee, Knoxville have pioneered a new technique for forming a two-dimensional, single-atom sheet of two different materials with a seamless boundary.
By rethinking a traditional method of growing materials, the researchers combined two compounds -- graphene and boron nitride -- into a single layer only one atom thick. Graphene, which consists of carbon atoms arranged in hexagonal, honeycomb-like rings, has attracted waves of attention because of its high strength and electronic properties.
“People call graphene a wonder material that could revolutionize the landscape of nanotechnology and electronics.”An-Ping Li, ORNL
“People call graphene a wonder material that could revolutionize the landscape of nanotechnology and electronics,” ORNL’s An-Ping Li said. “Indeed, graphene has a lot of potential, but it has limits. To make use of graphene in applications or devices, we need to integrate graphene with other materials.”
One method to combine differing materials into heterostructures is epitaxy, in which one material is grown on top of another such that both have the same crystalline structure. To grow the 2-D materials, the ORNL-UT research team directed the growth process horizontally instead of vertically.
The researchers first grew graphene on a copper foil, etched the graphene to create clean edges, and then grew boron nitride through chemical vapor deposition. Instead of conforming to the structure of the copper base layer as in conventional epitaxy, the boron nitride atoms took on the crystallography of the graphene.
“The graphene piece acted as a seed for the epitaxial growth in two-dimensional space, so that the crystallography of the boron nitride is solely determined by the graphene,” UT’s Gong Gu said.
Not only did the team’s technique combine the two materials, it also produced an atomically sharp boundary, a one-dimensional interface, between the two materials. The ability to carefully control this interface, or “heterojunction,” is important from an applied and fundamental perspective, says Gu.
The new technique also allows researchers to experimentally investigate the scientifically intriguing graphene-boron nitride boundary for the first time.
The research team anticipates that its method can be applied to other combinations of 2-D materials, assuming that the different crystalline structures are similar enough to match one another.
This story is reprinted from material from Oak Ridge National 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.