Resonant tunnelling diode speeds ahead of 5G

Researchers at the US Naval Research Laboratory have developed an RTD (resonant tunnelling diode), a new gallium nitride-based electrical component with performance claimed to be beyond the anticipated speed of 5G.

Storm and Growden with their molecular beam epitaxy system that develops gallium nitride-based (GaN) semiconductors (Image: US Navy photo by Jonathan Steffen)

The fifth-generation network technology is now just starting to roll out across the United States.

NRL’s David Storm, a research physicist, and Tyler Growden, an electrical engineer and NRC post-doc, have reported their electronic component diode research in Applied Physics Letters.

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“Our work showed that gallium nitride-based RTDs are not inherently slow, as others suggested,” Growden said in a statement. “They compare well in both frequency and output power to RTDs of different materials.”

The diodes are said to enable extremely fast transportation of electrons to take advantage of quantum tunnelling. In this tunnelling, electrons create current by moving through physical barriers, taking advantage of their ability to behave as particles and waves.

According to NEL, Storm and Growden’s design for gallium nitride-based diodes displayed record current outputs and switching speeds, enabling applications requiring electromagnetics in the millimetre-wave region and frequencies in terahertz. Such applications could include communications, networking, and sensing.

The team developed a repeatable process to increase the diodes yield to approximately 90 per cent compared to previous typical yields of around 20 per cent.

Storm said accomplishing a high yield of operational tunnelling devices can be difficult because they require sharp interfaces at the atomic level and are very sensitive to many sources of scattering and leakage.

Sample preparation, uniform growth, and a controlled fabrication process at every step were the key elements to the diodes satisfactory results on a chip.

“Until now, gallium nitride was difficult to work with from a manufacturing perspective,” Storm said. “I hate to say it, but our high yield was as simple as falling off a log, and a lot of it was due to our design.”

Storm and Growden said they will continue refining their RTD design to improve the current output without losing power potential. They performed their work with colleagues at Ohio State University, Wright State University, plus industry partners.