Graphene Conducts Electricity Ten Times Better Than Predicted


Carbon layers grown on silicon carbide conduct electricity even better than theory predicted. Physicists have produced nanoribbons of graphene, the single-atom-thick carbon, that conducts electrons better than theory predicted even for the most idealised form of the material. The finding could help graphene realise its promise in high-end electronics, where researchers have long hoped it could outperform traditional materials such as silicon.
In graphene, electrons can move faster than in any other material at room temperature. But techniques that cut sheets of graphene into the narrow ribbons needed to form wires of a nano-scale circuit leave ragged edges, which disrupt the electron flow until recently when a team led by physicist Walt de Heer at the Georgia Institute of Technology in Atlanta has made ribbons able that conduct electric charges for more than 10 micrometres without meeting resistance.
This is a thousand times farther than in old type graphene nanoribbons. The ribbons made by de Heer’s team in fact conduct electrons ten times better than standard theories of electron transport suggest they should. This unimpeded motion means that circuits could transmit signals faster and without the overheating issues that hamper typical semiconductor chips.
The results, published online in Nature Magazine suggest that “…the electrons move down the edges of the ribbons more like light travels down an optical fibre, rather than the way electrons normally bump and scatter as they move in a standard conductor.” says de Heer.
Francisco Guinea, a theoretical physicist at the Institute of Materials Science in Madrid, says that the evidence for this ‘ballistic’ transport is absolutely amazing.
That the ribbons conduct even better than most theories predict remains a puzzle and even De Heer is reluctant to speculate why and he believes that they’re simple charge carriers.
Others are more sceptical that this result will herald a revolution. Years of theoretical work have shown that in narrow ribbons, disorder due to imperfections in the material will destroy this rapid conduction, says Antonio Castro Neto, director of the National University of Singapore’s Graphene Research Centre. If the researchers looked at longer ribbons they would see these effects, he says. “It’s unavoidable. Unfortunately, graphene is not the material one should use for digital applications,” he adds, instead recommending new semiconducting materials, such as phosphorene.