Gate-tuning of graphene plasmons, concept and experimental images (via University of California & Nature)
Graphene is back on the scene once again. Researchers from the University of California have found that they could use the super-material to turn electron waves both on and off by using a simple circuit. The team, led by Professor Dimitri Basov, made the discovery by stripping a 1-atom thick single layer of graphene from graphite. They then rubbed the material onto silicon-oxide chips where they then fired an infra-red laser onto the surface of the chips which created waves of electrons. They then measured the length and height of the oscillations (plasmons) produced using an atomic-force microscope. The team found that when the electrons reached the edge of the graphene surface they reflected back to the point of origin where they then would either add to, or cancel out, the subsequent waves.
The oscillation of plasmons resulted in a pattern which resulted in determining their wavelength and amplitude frequencies. The researchers found that when the connected a pair of electrodes to both the graphene and silicon layers they could alter these patterns which then formed an electrical circuit (or tunable plasmonic device). Theoretically, this method could be used to transmit data through extremely tight spaces where light wave-lengths (hundreds of nano-meters long) can’t squeeze through such as fiber-optics. That would mean that we could have super-efficient and ultrafast processors that would make today’s generation of CPU’s look archaic in comparison.
Another team from Spain, led by Frank Koppens, was successful in creating the same circuit; however they used a gas process to create their graphene sheet instead of shaving it off of graphite. As scientists continue to develop and create new technologies using the super-material, it makes me wonder what else might graphene be used to accomplish.
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