By Josh Perry, Editor
A team of researchers from the Technical University of Denmark (DTU) Center for Nanostructured Graphene, which was created explicitly for studying the electrical properties of graphene, and Aalborg University developed a method for creating and controlling a bandgap in graphene to enable the production of nanoscale electronics.
Researchers have found a method for patterning graphene to control its electrical properties. (Carl Otto Moesgaard/DTU)
For years, graphene has been considered a building block for next-generation electronics, but scientists were unable to pattern the one atom-thick material to introduce a bandgap, according to a report from DTU.
Initially, the DTU scientists had the same issue as previous efforts, but they recently had a breakthrough by encapsulating graphene in hexagonal boron nitride and using electron beam lithography to pattern the protective layer and the graphene with an array of holes.
“The holes have a diameter of approx. 20 nanometers, with just 12 nanometers between them – however, the roughness at the edge of the holes is less than 1 nanometer, or a billionth of a meter,” the article explained. “This allows 1,000 times more electrical current to flow than had been reported in such small graphene structures.”
In addition, researchers controlled the material’s band structure to determine its behavior. This allowed the scientists to think up new components and devices on the computer and then create them in the lab.
The research was recently published in Nature Nanotechnology. The abstract stated:
“Two-dimensional materials such as graphene allow direct access to the entirety of atoms constituting the crystal. While this makes shaping by lithography particularly attractive as a tool for band structure engineering through quantum confinement effects, edge disorder and contamination have so far limited progress towards experimental realization.
“Here, we define a superlattice in graphene encapsulated in hexagonal boron nitride, by etching an array of holes through the heterostructure with minimum feature sizes of 12–15 nm.
“We observe a magnetotransport regime that is distinctly different from the characteristic Landau fan of graphene, with a sizeable bandgap that can be tuned by a magnetic field. The measurements are accurately described by transport simulations and analytical calculations.
“Finally, we observe strong indications that the lithographically engineered band structure at the main Dirac point is cloned to a satellite peak that appears due to moiré interactions between the graphene and the encapsulating material.”