Graphene is amazing stuff. The one-atom-thick carbon-based material is not only the strongest, lightest material in the world, it’s completely flexible and can conduct electricity at least as well as copper. Discovered just over a decade ago, this remarkable material could revolutionize the way electronic devices are manufactured and used–and promises everything from faster internet speeds to improved smart phones to more efficient bioelectric sensory devices.
Up to now, however, the graphene revolution has been purely hypothetical. This is because scientists couldn’t find the right substance to use as a substrate, or supporting material, for the graphene–a substance that would have to survive the high temperatures needed for graphene growth.
Now, a research team at the National Institute of Standards and Technology (NIST) in Boulder, Colorado, may have brought graphene’s promise closer to becoming a reality. While searching for a workable substrate for graphene, the team found that a thin film of copper with massive crystalline grains could be just the right recipe. Their findings appear in the journal AIP Advances, which is produced by AIP Publishing.
The key advance is the grain size of the copper substrate, according to an AIP news release. Because the large grains are several centimeters in size, their relative bulk allows them to survive the high temperatures required for graphene growth, according to NIST researcher Mark Keller.
The inability of most copper films to survive this state of graphene growth “has been one problem preventing wafer-scale production of graphene devices,” Keller said.
Thin films are an essential component of many electronic, optical, and medical technologies, but the grains in these films are generally smaller than one micrometer–much smaller than those in the newly developed graphene substrate. To fabricate the new copper surface with grains some 10,000 times larger, the researchers came up with a two-step process, AIP explained.
First, they deposited copper onto a sapphire wafer held slightly above room temperature. Then they made the transformative step of annealing, or heat-treating, the film at a much higher temperature, near the melting point of copper. To demonstrate that their new large-grained film worked, the researchers successfully grew graphene grains 0.2 millimeters in diameter on the new copper surface.