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Black phosphorus is new 'wonder material'

Press Trust of India  |  Washington 

Move over, graphene! Black phosphorus may become the new 'wonder material' as it can be used for high-speed data communication on nanoscale optical circuits, scientists say.

Phosphorus, a highly reactive element commonly found in match heads, tracer bullets, and fertilisers, can be turned into a stable crystalline form known as black phosphorus.

In a new study, researchers from the University of Minnesota used an ultrathin black phosphorus film - only 20 layers of atoms - to demonstrate high-speed data communication on nanoscale optical circuits.

The devices showed vast improvement in efficiency over comparable devices using the earlier "wonder material" graphene, researchers said.

As consumers demand electronic devices that are faster and smaller, electronics makers cram more processor cores on a single chip, but getting all those processors to communicate with each other has been a key challenge for researchers.

The goal is to find materials that will allow high-speed, on-chip communication using light, researchers said.

Due to its unique properties, black phosphorus can be used to detect light very effectively, making it desirable for optical applications.

For the first time, the team created intricate optical circuits in silicon and then laid thin flakes of black phosphorus over these structures.

"After the discovery of graphene, new two-dimensional materials continue to emerge with novel optoelectronic properties," said Professors Mo Li, who led the research team.

"Because these materials are two-dimensional, it makes perfect sense to place them on chips with flat optical integrated circuits to allow maximal interaction with light and optimally utilise their novel properties," said Li.

The team demonstrated that the performance of the black phosphorus photodetectors even rivals that of comparable devices made of germanium - considered the gold standard in on-chip photodetection.

Germanium, however, is difficult to grow on silicon optical circuits, while black phosphorus and other two-dimensional materials can be grown separately and transferred onto any material, making them much more versatile.

The team also showed that the devices could be used for real-world applications by sending high-speed optical data over fibres and recovering it using the black phosphorus photodetectors.

The group demonstrated data speeds up to three billion bits per second, which is equivalent to downloading a typical HD movie in about 30 seconds.

The finding was published in the journal Nature Photonics.

First Published: Tue, March 03 2015. 17:57 IST