
Hexagonal boron nitride memristor for 6G RF MOSFET
An international collaboration has developed a 120GHz RF MOSFET for 6G using hexagonal boron nitride (hBN).
Researchers from the UAB Department of Telecommunications and Systems Engineering at the University of Barcelona have developed the MOSFET with twice the operating frequency of current silicon-based devices for 6G and without the need to apply a constant voltage.
hBN allows its ON or OFF state to be activated by applying an electrical voltage pulse instead of a constant signal. In this way, the energy savings that can be reached in 6G RF systems are very significant.
“Our research team from the Department of Telecommunications and Systems Engineering at the UAB was involved in the design of the devices and their experimental characterisation in the laboratory,” said researcher Jordi Verdú. “For the first time we have been able to demonstrate the operation of a switch based on hBN, a non-volatile material, in a frequency range of up to 120 GHz, which suggests the possibility of using this technology in the new 6G mass communications systems, where a very high number of these elements will be required.”
These devices use the property of memristance, the change in electrical resistance of a material when a voltage is applied. Until now, very fast switches had been developed experimentally from memristors created with two-dimensional networks of hexagonal boron nitride (hBN) bonded together to form a surface.
With this arrangement, the device frequency could reach up to 480 GHz, but only for 30 cycles. The new design uses the same material, but arranged in a superposition of layers (between 12 and 18 layers in total) that can operate at 260 GHz and with a sufficiently high stability of about 2000 cycles to be implemented in electronic devices.
The team showed switching in 21 devices with low-resistance states averaging 294 Ω and endurances of 2,000 cycles. With further biasing optimization, the resistance reduced to 9.3 ± 3.7 Ω over more than 475 cycles, and achieve an insertion loss of 0.9 dB at 120 GHz. The team also built a series–shunt device configuration with an isolation of 35 dB at 120 GHz.
The research was coordinated by the King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, with researchers from the University of Texas at Austin (USA), the Tyndall National Institute and University College Cork in Ireland.
