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When it comes to mobile phones, many people are only just making the switch from 3G to 4G, or even 5G, but those who like to keep up with the latest technology are already thinking about the next set up to the sixth generation of wireless mobile technology, 6G.
But it turns out that cannot happen without the help of wonder material graphene. Discovered in 2004, this single-layer, hexagonal matrix could be the key to faster communications and has implications for computing, the internet, and even global energy consumption.
In 2020, a $1 billion dollar investment was promised to kickstart 6G communications, as researchers forecast terahertz beams that will charge our phones, work unpowered devices, and improve sensing and positioning to within one centimeter.
But 5G is really only just emerging, and slowly at that. It is expected that 6G will be available by 2030, but much of the essential new hardware needed, like software programmable metasurfaces, does not exist yet.
The current copper sheets, printed circuit boards and conventional components just will not cut it. Power, performance, size and space constraints mean that intelligent reconfigurable surfaces and software-controlled metasurfaces are required to deliver the delicate far-infrared signals needed to massively advance smartphones, the Internet of Things (IoT), ICT, entertainment and medicine.
Graphene has a number of diverse and useful properties that make it ideal for numerous applications; used in metamaterials, it will become important for thermal, optical, electrical and electronic functions. It will be important in 6G active devices and the metamaterials essential to the manufacture of smart surfaces.
6G will not be successful without Reflective Intelligent Surfaces (RIS) - a revolutionary technology that can improve the performance of wireless data transmission systems - and they cannot succeed unless they are fabricated as metasurfaces affordably aligning, polarizing and redirecting beams with almost no electricity.
RIS will do more than just neaten and redirect the terahertz beams; it will also amplify them, and charge your phone and devices with no power – all with the use of graphene.
The biggest leap forward in the development of equipment will be batteryless devices, instead, the signal will provide the power. Fit-and-forget graphene supercapacitors could replace batteries as 6G devices require less power. These devices excel in energy and power density, making the most of graphene’s exceptional conductivity and large area density.
Graphene also exhibits great thinness, electrical conductivity and heat conduction, making it ideal for the smaller, thinner devices that consumers crave, which often show problems with heat dissipation.
Further developments will see the provision of device power by Wireless Information and Energy Transmission (WIET), along with energy harvesting. The technology will also have an impact on sensing and positioning. Next come optical devices and terahertz antennas for 6G and then transceivers, transistors, diodes, emitters.
A variety of optically stimulated graphene-based metasurfaces have been proposed and a number of dynamically controlled graphene multifunctional metasurfaces are being experimentally tested, including the so-called graphene field-effect transistor. The transistor features a large array of graphene reflective unit cells controlled independently by size and external static gate voltage for multifunctionality.
Other developments are making use of epitaxial graphene i.e., graphene grown by thermal decomposition on another surface. Epitaxial graphene on silicon carbide is being used in an efficient terahertz Schottky-diode detection scheme which could be used in 6G for ubiquitous sensing and positioning.
A second use sees epitaxial graphene on gallium nitride and promises the detection of ultrafast electronic processes as well as functional and single-molecule electronics, phononics and plasmonics.
Graphene-enabled on-chip optical data, spin-logic devices and 6G networks are expected to be undergoing development by 2030. Due to its unique band structure, graphene conductivity can be used to create reprogrammable optoelectronic and electric devices. A new type of optical transistor uses a high-temperature superconductor and graphene; in which graphene excels in insensitivity to light, massless electrons and transparency.
In summary, exploiting the wide range of benefits of graphene for metasurfaces, supercapacitors and various active components will lead to 6G systems becoming a trillion-dollar industry, and not only make for faster communications and improved internet but result in new materials that can charge phones and power our devices.
References and Further Reading
Harrop, D and Edmondson J, (2021) 6G Communications Market, Devices, Materials 2021-2041, IDTechEx: https://www.idtechex.com/en/research-report/6g-communications-market-devices-materials-2021-2041/797. Accessed 19th May 2021.
Harrop, D et al (2021) 6G Communications Reconfigurable Intelligent Surfaces Roadmap, Materials, Market 2021-2045 IDTechEx: https://www.idtechex.com/en/research-report/6g-communications-reconfigurable-intelligent-surfaces-roadmap-materials-market-2021-2045/805. Accessed 19th May 2021.
Harrop, D. (2021) Graphene for 6G Communications IDTechEx: https://www.idtechex.com/fr/research-article/graphene-for-6g-communications/23776. Accessed 19th May 2021.