Graphene has revealed yet more interesting characteristics, as researchers in the US investigate the way the two-dimensional form of carbon reacts to light. Regular readers will not be surprised to learn that it differs a little from a typical semi-conductor.
When exposed to light, graphene – a one-atom-thick sheet of carbon – produces so-called 'hot carriers' that generate a photocurrent. These are normally only seen at extremely low temperatures, but according to MIT and Harvard university researchers, graphene will produce them right up to room temperature.
Usually, light falling on a semi conductor will produce electron-hole pairs which in turn produce a photocurrent. This is known as the photoelectric effect.
According to Institute of Physics publication nanotechweb, some researchers suspected that a graphene might be slightly different. Indeed, when the MIT and Harvard team investigated, they detected a photocurrent six times higher than has been seen in previous graphene optoelectric devices.
Researcher Pablo Jarillo-Herrero told the publication that this was caused by the photothermoelectroic effect: "It turns out that when you shine a light on graphene, the electrons in the material heat up, and remain hot, while the underlying carbon lattice remains cool." These hot electrons then produce a current.
The work will be published in the journal Science, but you can read more here.