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#Science

Black phosphorus pegged as silicon-replacement candidate in transistors

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Ever since scientists first discovered the properties of Graphene, two-dimensional materials have garnered a lot of attention for the possible use in electronics – specifically transistors – and one such material that researchers have been actively investigating is black phosphorous.

Black Phosphorous is quite similar to graphite and can also be separated into layers just one-atom thick known as Phosphorene. The natural semiconducting properties of black phosphorous and the capability of separating it into one-atom thick layers makes it a strong contender in the race of replacing silicon. Graphene is definitely one of the contenders, but owing to semiconducting properties of black phosphorous, it is a more suitable replacement.

The material is central to a research carried out by scientists at McGill University and Université de Montréal, which has provided evidence that black phosphorus could emerge as a strong candidate.

In a study published today in Nature Communications, the researchers report that when electrons move in a phosphorus transistor, they do so only in two dimensions. The finding suggests that black phosphorus could help engineers surmount one of the big challenges for future electronics: designing energy-efficient transistors.

Researchers observed the electrons of phosphorous under the influence of a magnetic field in experiments performed at the National High Magnetic Field Laboratory in Tallahassee, Florida. They observed that electrons are able to be pulled into a sheet of charge which is two-dimensional, even though they occupy a volume that is several atomic layers in thickness.

The finding is significant because it could potentially facilitate manufacturing the material — though at this point “no one knows how to manufacture this material on a large scale.”

“There is a great emerging interest around the world in black phosphorus,” says Thomas Szkopek, an associate professor in McGill’s Department of Electrical and Computer Engineering and senior author of the new study. “We are still a long way from seeing atomic layer transistors in a commercial product, but we have now moved one step closer.”

“Transistors work more efficiently when they are thin, with electrons moving in only two dimensions,” said Szkopek. “Nothing gets thinner than a single layer of atoms.”

Researchers say that the key to lower operating voltage of transistors so that they generate less heat there is a need to design transistor at the atomic level and scientists who intend to work at these levels would require a variety of atomic-layered materials including an ideal semiconductor, an ideal metal, and an ideal dielectric.

“All three components must be optimized for a well designed transistor. Black phosphorus fills the semiconducting-material role”, Szkopek said.