It is literally big news for nanotechnology applications that may use graphene – a European consortium of researchers (UK, Sweden, Italy) has learned how to make bigger pieces. That’s phrased a little too colloquially. Previously samples of graphene, a one atom thick honeycomb of carbon, were laboriously created as tiny flakes fractions of a millimeter in size. With the new process, which grows the graphene layers on silicon carbide, sizes up to 50 mm2 have been achieved. So what is, pardon the expression, the big deal?
Graphene sheets are the hottest shape in carbon nanotechnology, which is to say that researchers and engineers continually find new ways to use them in applications ranging from semiconductors (computer chips) to LCD screens and solar panels. Graphene is a versatile material, quite strong and highly conductive, despite its extreme thinness. However, practical applications of graphene have been held back because it was available only in very small sizes.
Another limiting factor for commercial purposes was the precise measurement of graphene’s electrical properties. In particular, the measurement of the quantum Hall effect is considered critical for precision electrical engineering. The quantum Hall effect is measured at very cold temperatures (near absolute zero) and under strong magnetic fields. The result is an extremely precise measurement of electrical resistance, a new practical standard called the von Klitzing constant. Relatively few semiconductor materials have been measured with sufficient precision to this standard. Although it was suspected that Graphene would have a superior quantum Hall effect, it was not available in the quantities needed for measurement – until now. One of the follow-on effects of the research was to provide enough graphene so that it could be tested. It was found that graphene not only can be measured with great precision, but that it demonstrates the quantum Hall effect at higher temperatures than other semiconductor materials. This makes it easier to test for manufacturing standards – further increasing the commercial advantage of graphene.
Prof Alexander Tzalenchuk from NPL’s Quantum Detection Group and the lead author on the Nature Nanotechnology paper observes: “It is truly sensational that a large area of epitaxial graphene demonstrated not only structural continuity, but also the degree of perfection required for precise electrical measurements on par with conventional semiconductors with a much longer development history.”
Dr JT Janssen, an National Physical Laboratory (UK) Fellow who worked on the project, said: “We’ve laid the groundwork for the future of graphene production, and will strive in our ongoing research to provide greater understanding of this exciting material. The challenge for industry in the coming years will be to scale the material up in a practical way to meet new technology demands. We have taken a huge step forward, and once the manufacturing processes are in place, we hope graphene will offer the world a faster and cheaper alternative to conventional semiconductors”.