Graphene: the sexy, thin supermodel queen of the material world

Posted by Emory Kale
It's really, really thin. It's tough as lead boots. It's sexy. It's graphene. And, the science world gets all hot and heavy when it is around. Brainiacs just love the super-material.
It is a one-atom thick carbon-based material that is now recognized as the thinnest and strongest material in the world. And if that wasn't enough, it can conduct electricity as well as copper. It is a miracle material that will make the Internet go faster, and eventually let us see astronauts dressed in skintight suits instead of looking like they were swallowed by the Michelin homme
As we reporter earlier, graphene has extreme conductivity and is completely transparent while being inexpensive and nontoxic. This makes it a perfect candidate material for transparent contact layers for use in solar cells to conduct electricity without reducing the amount of incoming light - at least in theory.

Graphene, in a real world setting has been questionable as there is no such thing as "ideal" graphene - a free floating, flat honeycomb structure consisting of a single layer of carbon atoms: interactions with adjacent layers can change graphene's properties dramatically. Our lovesick scientitsts could think about it, but not really get to play with it the way they wanted. Because, to grow graphene scientists needed to create the material in very high temperatures and they hadn't managed to find a substrate that could withstand the heat. Nothing was hot enough for graphene.

Now a research team at the National Institute of Standards and Technology (NIST) in Boulder, Colo., may help bring graphene's promise closer to reality. While searching for an ideal growth platform for the material, investigators developed a promising new recipe for a graphene substrate: a thin film of copper with massive crystalline grains. The team's findings appear in the journal AIP Advances.
The key advance is the grain size of the copper substrate. The large grains are several centimeters in size – massive by microelectronics standards – but their relative bulk enables them to survive the high temperatures needed for graphene growth.
Optical microscope image of copper film, mostly destroyed during graphene growth
The inability of most copper films to survive this stage of graphene growth "has been one problem preventing wafer-scale production of graphene devices," said NIST researcher Max Keller.
Thin films are an essential component of many electronic, optical, and medical technologies, but the grains in these films are typically smaller than one micrometer. To fabricate the new copper surface, whose grains are about 10,000 times larger, the researchers came up with a two-step process.
First, they deposited copper onto a sapphire wafer held slightly above room temperature. Second, they added the transformative step of annealing, or heat-treating, the film at a much higher temperature, near the melting point of copper. To demonstrate the viability of their giant-grained film, the researchers successfully grew graphene grains 0.2 millimeters in diameter on the new copper surface.
So, graphene is not theoretically great. It is great. And as atomic materials go, it is damn sexy. I bet you want some, don't you? You know you do.