If you are reading this article, you most likely used semiconductors. These materials, usually silicon, underpin most of our technology. They are incredibly useful, as one would imagine, but they are not without limitations. One of them, about the speed of transmission, might have now been overcome in a special superatomic semiconductor. This makes it the best semiconductor yet when it comes to energy transport.
In semiconductors, electrons can jump from one free spot to another, which is technically called a hole. Electrons move by themselves or they might move together with the hole. In this latter state, they are a quasiparticle, called an exciton, which behaves like a real particle but is actually just a peculiar interaction.
This is not the only quasiparticle at play in semiconductors. The natural vibrations in the material can also be represented by quasiparticles known as phonons and when they interact with the excitons they scatter them, releasing heat and reducing the maximum speed the information and energy can travel through semiconductors.
Well, until this one. The new material in question is made of Rhenium, Selenium, and Chlorine and it is known by its chemical formula Re6Se8Cl2. In the material, something weird happens between the phonons and the excitons. Instead of scattering, they merge into a new quasiparticle: the acoustic exciton-polaron.
This new quasiparticle allows information and energy transfer that's twice as fast as the speed electrons move through silicon. But it is not just motion, it is also processing speed. These quasiparticles are controlled by light and not an electrical current so that processing has the potential to get a million times faster than the current semiconductor. And it doesn’t require to be cooled down to very low temperatures for those quantum effects to manifest.
“In terms of energy transport, Re6Se8Cl2 is the best semiconductor that we know of, at least so far,” chemistry professor Milan Delor from Columbia University said in a statement.
Having discovered this amazing and unexpected property in Re6Se8Cl2, the team is now set to understand why this acoustic exciton-polaron emerges in this material. Understanding this is important in the search for better semiconductors.
Rhenium is one of the rarest elements on Earth so the commercial suitability of this semiconductor is non-existent unless we suddenly find a lot of rhenium somewhere. But the fact that this property exists in this material suggests that it might be found elsewhere too. In materials that are much cheaper to manufacture.
“This is the only material that anyone has seen sustained room-temperature ballistic exciton transport in. But we can now start to predict what other materials might be capable of this behavior that we just haven’t considered before,” said Delor. “There is a whole family of superatomic and other 2D semiconductor materials out there with properties favorable for acoustic polaron formation.”
The research is published in the journal Science.