Breaking the graphene barrier

IMAGINE TONNES of data being transferred from Mars to Earth in just a few minutes, or your high definition movie getting downloaded even before you can blink an eye. My team at Indian Institute of Science Bangalore, has made a major breakthrough in graphene-based transistor technology, which can eventually have such communication capability.

Graphene is a wonder material with many special properties. It was known to scientists for several years but was isolated for the first time only in 2004, a feat that fetched its discoverer the Nobel Prize six years later. Chemically, it is only carbon, just like graphite which is nothing but layers of graphene stacked one atop the other, but its uniqueness comes from its structure. It is the thinnest and lightest material known, just one atom thick. Essentially, it is just a twodimensional material.

We were particularly interested in graphene’s ability to control flow of electrons at a speed several notches higher than the materials we currently have. Electrons in graphene behave differently than in any other material; as such, it has the potential to revolutionise electronics. For example, graphene transistors can potentially enable communication in the terrahertz frequency range, which is 1,000 times faster than frequencies used in today’s communication. In layman's terms, one can think of wireless communication that may be 1,000 times faster than 4G or 5G technologies. It can also enable flexible, transparent electronics.

But the very structure that lends the special properties to graphene also acts as a huge barrier to its utilisation. Essentially, the problem is inherent in its dimension. Everything we otherwise work with is three-dimensional, whereas graphene is two-dimensional. It might not be very obvious, but there is a compatibility problem. These different materials are unable to “communicate” with each other.

The problem comes when graphene is put in contact with any other material. As soon as it comes in contact with a metal, it gets contaminated by electrons, which behave conventionally. The contamination often nullifies the special properties of electrons that graphene intrinsically possesses. For this reason, attempts to use graphene in electronics have so far not produced any significant improvement. For example, the terrahertz frequencies are yet to be achieved.

We have been working on this fundamental concern for some time. Our effort was to improve the contact chemistry without contaminating it. While doing this, we had to go into a deep understanding of the quantum physics and quantum chemistry of such contacts. After two years of work, we have now been able to break the barrier, which was unsolved for many years. The discovery and subsequent invention has broken several performance records; it was presented at International Electron Device Meeting, the world’s most competitive platform in the field of electron devices.

With this breakthrough we foresee commercialisation of THZ graphene technology in the near future, which was earlier projected beyond 2022. This kind of communication capability is also highly desired for communication between satellites, between spacecrafts and in interplanetary operations. For example, the data that we receive from Mars in months, we can get the same in a few hours with a THZ link. In addition to this it can be used for homeland security. THZ radiation can non-invasively detect if someone is carrying a metallic object like a weapon or a plastic explosive under the clothes, without penetrating the skin. This can be done remotely without informing the person that she/he is being scanned. Hence this is a technology of high importance for India.