Since its inception, scientists have tried to exploit graphene to produce nano-sized electronics. However, since graphene is only an atom thick, all atoms are exposed to the outside world, and even small amounts of defects and impurities impede its properties. Now, Graphene Flagship researchers at the Technical University of Denmark (DTU) solved this problem by protecting graphene with insulating layers of hexagonal boron nitride, another two-dimensional material with insulating properties.
Since 2010, scientists at Graphene Flagship partner DTU have tried to tailor the electrical properties of graphene, by making a very fine pattern of holes, so that channels through which an electric power can flow freely are formed. "Creating nanostructured graphene turned out to be amazingly difficult, since even small errors wash out all the properties we designed it to have," comments Peter Bøggild, researcher at DTU.
Now, the DTU team has made a leap forward. They encapsulated graphene with another 2D material, hexagonal boron nitride, which is very similar to graphene, but electrically insulating. Then, using nanolithography, they carefully drilled nanoscopic holes in graphene through the protective layer of boron nitride. The holes have a diameter of approximately 20 nanometers, and are separated from each other with just 12nm. This great precision makes possible to send an electrical current through the graphene that is 100-1000 times higher than typical numbers for lithographically carved nanographene.
"We have shown that we can control graphene's band structure and that deterministic design of nanoelectronics is realistic. Looking solely at electronics, this means that we can make insulators, transistors, conductors and perhaps even superconductors, as our nanolithography can preserve the subtle inter-layer physics that was recently shown to lead to superconductivity in double-layer graphene. However, it goes way beyond that," says Bøggild.
"When we control the band structure, we have access to all of graphene's properties. In other words, we could sit in front of the computer and dream up other applications - and then go to the laboratory and make them happen. There are plenty of practical challenges, but the fact that we can tailor electronic properties of graphene is a big step towards creating new electronics with extremely small dimensions."
