In a breakthrough that could transform the future of wireless communication, researchers at Nagoya University in Japan have created a tiny electronic device that may pave the way for sixth-generation (6G) networks.
The device, called a resonant tunnel diode (RTD), can now operate at room temperature using only safe, non-toxic semiconductor materials.
This is a big deal because RTDs are one of the most promising components for handling terahertz waves—extremely fast vibrations of electromagnetic energy that occur a trillion times per second.
Terahertz technology has long been seen as the key to enabling ultra-fast, high-capacity wireless communication.
It could make future mobile networks hundreds of times faster and more energy efficient than today’s systems.
Until now, though, RTDs have only worked under laboratory conditions, at extremely cold temperatures.
Why this matters for 6G
6G networks are expected to rely on terahertz waves to move massive amounts of data instantly. Imagine downloading entire movies in seconds, streaming immersive virtual reality without lag, or connecting billions of smart devices with almost no delay.
To achieve this vision, researchers need devices that can reliably generate and control terahertz signals at everyday temperatures.
The new RTD achieves this by using only materials from Group IV of the periodic table—common elements such as germanium and silicon—rather than the rare and toxic substances (like indium and arsenic) used in older designs. This makes the technology safer, cheaper, and easier to integrate into existing manufacturing systems.
How the breakthrough happened
At the heart of an RTD is a quantum effect called “tunneling.” Electrons pass through ultra-thin barriers of semiconductor materials, which are stacked only a few atoms thick.
The way these layers are arranged allows the device to produce an unusual effect called negative differential resistance. In simple terms, this means that as the voltage increases, the current can actually decrease—a property that enables the high-frequency oscillations needed for terahertz communication.
Previously, RTDs made from Group IV materials only worked at cryogenic temperatures of about –263°C. That made them impractical for consumer electronics. The Nagoya team solved the problem by carefully controlling the growth of the semiconductor layers.
They introduced hydrogen gas during the manufacturing process, which helped create smooth and defect-free barriers. This eliminated unwanted “leakage paths” for electrons and allowed the RTD to function at room temperature (around 27°C).
Senior researcher Dr. Shigehisa Shibayama explained that if the layers are mixed or contain defects, the RTD cannot work properly. By preventing this, the team unlocked the key to practical performance.
While there is still more work to do before these devices are ready for commercial networks, this milestone brings us closer to real-world terahertz technology.
With safer materials and room-temperature operation, RTDs may soon become the backbone of lightning-fast, energy-efficient 6G wireless systems.
