2D materials may lead to faster, smaller, efficient devices

Manipulation of 2D materials such as graphene could make modern day electronic and photonic devices faster, smaller and efficient, a new study suggests.
Two-dimensional (2D) materials are a class of nanomaterials that are only a few atoms in thickness.
Electrons in these materials are free to move in the two-dimensional plane, but their restricted motion in the third direction is governed by quantum mechanics.
The 2D materials such as graphene, transition metal dichalcogenides and black phosphorus have garnered tremendous attention from scientists for their amazing properties and potential to improve electronic and photonic devices.
Researchers, including those from the University of Minnesota and Stanford University in the US, examined the optical properties of several dozens of 2D materials.

They analysed how polaritons, a class of quasiparticles formed through the coupling of photons with electric charge dipoles in solid, allow researchers to marry the speed of photon light particles and the small size of electrons.

"With our devices, we want speed, efficiency and we want small. Polaritons could offer the answer," said Tony Low, a University of Minnesota electrical and computer engineering assistant professor and lead author of the study.
By exciting the polaritons in 2D materials, electromagnetic energy can be focused down to a volume a million times smaller compared to when its propagating in free space.
"Layered two-dimensional materials have emerged as a fantastic toolbox for nano-photonics and nano-optoelectronics, providing tailored design and tunability for properties that are not possible to realise with conventional materials," said Frank Koppens, group leader at the Institute of Photonic Sciences at Barcelona, Spain, and co-author of the study.

"This will offer tremendous opportunities for applications," said Koppens.
"The study of the plasmon-polaritons in two-dimensions is not only a fascinating research subject, but also offers possibilities for important technological applications," said Phaedon Avoruris, IBM Fellow at the IBM T J Watson Research Center.
"For example, an atomic layer material like graphene extends the field of plasmonics to the infrared and terahertz regions of the electromagnetic spectrum allowing unique applications ranging from sensing and fingerprinting minute amounts of biomolecules, to applications in optical communications, energy harvesting and security imaging," said Avoruris.
The study also examined the possibilities of combining 2D materials. Researchers point out that every 2D material has advantages and disadvantages. Combining these materials create new materials that may have the best qualities of both.

The findings were published in the journal Nature Materials.