High currents in graphene for ultra-fast electronics

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Electrons in graphene are extremely mobile and react quickly, according to a research team from the Institute of Applied Physics at TU Wien, the Helmholtz-Center Dresden-Rossendorf and the University of Duisburg-Essen.

Impacting xenon ions on a graphene film was said to cause a large number of electrons to be torn away from the graphene in a precise spot. However, the material could replace the electrons within femtoseconds, which resulted in extremely high currents.

As the highly charged ion approaches the graphene film, it starts tearing electrons away from the graphene due to its strong electric field. The ion can extract more than 20 electrons from the graphene film.

This means that electrons are then missing from the graphene layer, so the carbon atoms surrounding the point of impact of the xenon ions are positively charged.

“You would expect these positively charged carbon ions to repel one another, flying off in what is called a Coulomb explosion and leaving a large gap in the material,” says postdoctoral assistant Richard Wilhelm. “But the positive charge in the graphene is neutralised almost instantaneously.”

This is possible because the electrons in the graphene can be replaced within several femtoseconds.

“The current density is around 1000 times higher than that which would lead to the destruction of the material under normal circumstances – but over these distances and time scales, graphene can withstand such extreme currents without suffering any damage,” explains PhD student Elisabeth Gruber.

“The hope is that for this reason, it will be possible to use graphene to build ultra-fast electronics. Graphene also appears to be suited for use in optics, for example in connecting optical and electronic components,” concludes Professor Fritz Aumayr.