Graphene—a sheet of sp2-bonded carbon atoms one atom thick—increasingly shows promise for nanotech applications, but ultimately it would be useful to be able to control the edges of the planar sheet to atomic precision. In one step toward the goal of atomically precise graphene nanostructures, researchers have demonstrated atomically precise cuts through a few graphene layers. From the University of Pennsylvania, via AAAS EurekAlert “Penn Scientists Carve Functional Nanoribbons Using Super-Heated, Nano-Sized Particles of Iron“:
Due to its remarkable electronic properties, few layer graphene, or FLG, has emerged as a promising new material for use in post-silicon devices that incorporate the quantum effects that emerge at the nanoscale. Now, physicists at the University of Pennsylvania have demonstrated a new method by which FLG can be etched along flawless, crystallographic axes by using thermally activated nanoparticles, a technique that results in atomically precise, macroscopic length ribbons of graphene. The advance could enable atomically precise, and far simpler, construction of integrated circuits from single graphene sheets with a wide range of technological applications.
A.T. Charlie Johnson, professor in the Department of Physics and Astronomy at Penn, and his team have demonstrated this new etching process which relies on catalytic metal particles to etch the graphene along precise atomic directions.
Johnson’s team is now attempting to refine their control of the process and test Penn’s capability to fabricate devices whose properties will reflect the intrinsic quality of atomically precise graphene.
“Graphene is a great material for electronics, but it would be even better if it were possible to create devices with crystallographic edges, that is, edges where the atoms lie along single lines in the graphene plane,” Johnson said. “Standard etching techniques being used in the semiconductor industry do not allow this sort of fabrication. Instead, they produce rough edges with lots of atomic scale defects that limit the performance of the fabricated devices.”
Specifically, the Penn team investigated the construction of atomically precise graphene nanoribbons in which charge-carrying electrons are confined in a nearly two-dimensional, lateral plane and the electronic properties of the ribbon are controlled by the width and specific crystallographic orientation of the material. These structures hold enormous promise as nanoscale devices, with the advantage that graphene’s two-dimensionality lends itself to existing device architectures based on planar geometries.
The research was published in Nano Letters (abstract).