A domestic research team has developed a quantum device that can rapidly process signals in the terahertz (THz) band needed for next-generation ultra-high-speed communications such as sixth-generation (6G) mobile networks. Observers said the advance raises the prospects for commercialization by simultaneously reducing the high-voltage drive and thermal damage issues that have been considered key hurdles for existing technology.
A research team led by Park Hyeong-ryeol, a physics professor at Ulsan National Institute of Science and Technology, said on the 30th that, in collaboration with a team led by Lee Sang-woon, a physics professor at Ajou University, they implemented a terahertz quantum device that operates stably even under relatively weak electric fields.
A terahertz quantum device operates by inducing electron "tunneling (a quantum phenomenon in which particles traverse an energy barrier)" using terahertz waves that oscillate trillions of times per second. Because it can realize an ultra-high-speed operating regime that semiconductor devices struggle to reach, it has drawn attention as a next-generation signal-processing technology, including for 6G Network.
However, existing devices required a strong electric field of about 3 V/nm to induce tunneling, causing significant heat generation. The heat can melt metal electrodes or damage the structure, making stable operation and device reliability the key challenges.
The researchers found a solution by replacing the insulating layer material inserted between the metal electrodes in the device structure from aluminum oxide to titanium dioxide. Titanium dioxide lowers the energy barrier that electrons must cross, allowing tunneling to occur smoothly even at an electric field roughly one-fourth of the previous level. As a result, they were able to significantly reduce the burden of drive voltage and the risk of thermal destruction.
They also improved microscopic defects that can occur during the process of coating the insulating layer on the metal electrodes using atomic layer deposition, a technique used in semiconductor processing. Because it stacks thin films layer by layer at the atomic level, it is advantageous for improving uniformity and minimizing defects, they noted.
Park Hyeong-ryeol said, "This is a result that fundamentally reduces the high-voltage drive and thermal breakdown issues that have hindered the commercialization of terahertz quantum devices," adding, "It will become a fundamental technology that can expand beyond 6G to future optical communication devices and high-sensitivity quantum sensing."
The findings were published online on the 20th in ACS Nano, an international journal in the field of nanoscience.
References
ACS Nano (2025), DOI: https://doi.org/10.1021/acsnano.5c12360