Electronic components for 5G

The digital revolution we’re currently experiencing is based on the transmission of huge quantities of data at ever-increasing speeds. It’s this constant flow of information that enabled us, for example, to stay in touch with our loved ones or work remotely during the recent pandemic.

This revolution, however, comes at a significant environmental cost,because the energy consumed by our electronic devices is constantly increasing. Access to the non-renewable raw materials at the heart of electronic chips has become a major geopolitical issue.

The Institute of Electronics, Microelectronics and Nanotechnology(IEMN¹) at the University of Lille is heavily involved in the search for solutions to build the electronics of the future, with ever-better performance and lower environmental costs.

It was against this backdrop that a research group from this institute joined forces with a Texan team to develop new radio frequency switches(RFswitches). These switches, which are widely used in electronic devices, perform many functions. These, for example, are what enable smartphones to switch from Bluetooth to Wi-Fi, 4G or 5G. The problem is that they are power-hungry, requiring constant power. This has an impact on battery life.

The Texan group had developed its first switches based on two-dimensional materials (only one layer of atoms thick) in 2018. More energy-efficient, these devices consisted of a single sheet of molybdenum disulfide sandwiched between two metal electrodes. However, they didn’t cope well with high levels of electrical power. In addition, the team had not been able to determine whether they were capable of operating at electrical signal frequencies greater than 50 gigahertz. However, modern communications increasingly require us to go beyond these limits, especially when it comes to transporting high-definition video.

It was at a conference, during a discussion in the streets of San Sebastián, in Spain’s Basque Country, that the collaboration around these switches began. This discussion took place between IEMN’s Emiliano Pallecchi and Texas team manager Deji Akinwande. During these exchanges, which continued the following year with two other IEMN professors, Henri Happy and Guillaume Ducournau, the two teams realised that a new material, hexagonal boron nitride (hBN), should be able to tolerate higher powers. It belongs to a new family of two-dimensional materials (2D materials) currently being researched at the University of Lille.

But it still needs to be tested experimentally. To achieve this, the Lille team’s expertise and the IEMN’s state-of-the-art facilities are essential. After two years’ work, tests carried out at IEMN show that hBN-based switches tolerate high power levels (100 milliwatts) and operate at frequencies up to 200 GHz: one test showed that the switch could transmit a high-definition video stream very quickly.

As predicted by the research teams, these switches are particularly energy-efficient. In fact, they don’t need to be permanently powered, and the energy expended when they switch is lower than that of all other RF switch technologies. The Lille-Texas collaboration, meanwhile, is ongoing, working to improve the reliability of these devices and make progress towards the electronic future of 6th generation (6G) mobile networks.

Scientific publication

• Analogue switches made from boron nitride monolayers for application in 5G and terahertz communication systems,Nature Electronics.
• The IEMN co-signatories are Emiliano Pallecchi, Guillaume Ducournau and Henri Happy.

¹ (Univ. Lille/CNRS/Centrale Lille/ICL/UPHF)