Researchers Create Nanoscale Device 10 Times Faster Than the Fastest TransistorsMarch 27, 2020 by Alessandro Mascellino
Scientists from the Power and Wide-band-gap Electronics Research Laboratory (POWERlab) in Lausanne, Switzerland, have built a nanodevice capable of producing high-power Terahertz (THz) waves.
The device does so by generating a powerful "spark," with a voltage spiking from 10 V (or lower) to 100 V in the range of a picosecond.
The team, led by Professor Elison Matioli, said the technology could one day be installed in smartphones and other hand-held devices, thus helping engineers develop faster wireless communications and, further down the road, potentially revolutionize medical and security imaging systems.
Exploiting Terahertz Waves
These types of waves are located in the electromagnetic spectrum between microwave and infrared radiation.
Terahertz waves oscillate at extremely high frequencies — between 100 billion and 30 trillion cycles per second and can penetrate various materials, including wood and stone walls. They can also carry a substantial quantity of data as well as to detect air pollution.
On account of these properties, engineers and scientists alike have been trying to exploit THz waves to build, among other things, the wireless devices of the future.
However, traditional electronic devices can only switch at speeds of up to one volt per picosecond, making them at least ten times slower than necessary to produce high-power THz waves.
It is not surprising then that most attempts to achieve this goal through conventional electronics have translated into cumbersome and expensive procedures.
A flexible substrate that the nanodevice can be implemented through. Image used courtesy of EPFL / POWERlab.
To build the new nanodevice, Matioli’s team placed two metal plates 20 nanometers apart, then applied incremental voltage to one of them. This caused the electrons on the plate to surge and to form a nanoplasma. Once the voltage reached a certain threshold, the electrons were then transferred to the other plate.
The research observed that, with an estimated 50 million signals every second, the device created a high-intensity pulse that produced high-frequency waves. When attached to an antenna, the device was able to produce, channel and radiate high-energy THz waves.
Commenting on the news, Matioli said that attaining both high-energy and high-frequency pulses was a remarkable achievement. "High-frequency semiconductor devices are nanoscale in size,” he explained. “They can only cope with a few volts before breaking out. High-power devices, meanwhile, are too big and slow to generate terahertz waves.”
To circumvent the problem, the POWERlab researchers then decided to merge principles related to the old field of plasma with state-of-the-art nanoscale fabrication techniques. "High-frequency, high-power, and nanoscale aren't terms you'd normally hear in the same sentence," he said.
Since they are a type of non-ionizing radiation, THz waves pose no risk to human health, the researchers claimed. In fact, successful if bulkier and more expensive attempts of harvesting this technology resulted in applications related to airport scans in the past.
Now, the new research in the field opens up possibilities not only in wireless communications applications but also those adjacent to imaging systems developed for healthcare and security purposes.
Furthermore, given the relative simplicity of the construction of these nanodevices, they could be produced en-masse at a very low cost. "These nanodevices, on one side, bring an extremely high level of simplicity and low-cost, and on the other side, show excellent performance,” said Ph.D. student Mohammad Samizadeh Nikoo, who is also the study’s first author.
The researcher said, looking at the future, this technology could lend itself to a number of applications, including the integration with other electronic devices such as transistors.
“Considering these unique properties,” Samizadeh concluded, “nanoplasma can shape a different future for the area of ultra-fast electronics."