Scientists have taken an important step toward the ultra-fast technologies expected to power future 6G communications.
A research team affiliated with Ulsan National Institute of Science and Technology has developed a new quantum device that operates at terahertz speeds while avoiding a problem that has long limited this technology: heat damage caused by intense electric fields.
The work was led by Hyeong-Ryeol Park from UNIST’s Department of Physics, in collaboration with Sang Woon Lee at Ajou University. Their findings were published in the journal ACS Nano.
Terahertz quantum devices are widely seen as key building blocks for next-generation communication systems.
Terahertz waves oscillate trillions of times per second, allowing data to be processed far faster than today’s electronics.
These devices rely on a quantum effect called tunneling, where electrons pass through energy barriers that would be impossible according to classical physics.
The challenge is that making tunneling happen usually requires extremely strong electric fields—so strong that they generate intense heat. In previous devices, this heat often damaged or even melted the metal electrodes, preventing reliable, long-term operation.
The UNIST-led team tackled this problem by rethinking the materials used inside the device. Traditional designs rely on aluminum oxide as the insulating layer between metal electrodes.
Instead, the researchers used titanium dioxide, a material that offers a lower energy barrier for electrons.
This change makes a big difference. Because electrons can tunnel more easily through titanium dioxide, the device can operate at much lower electric fields—about one quarter of what was previously needed. Lower electric fields mean less heat, dramatically reducing the risk of damage.
Gangseon Ji, the study’s first author, explained that the goal was not to force electrons harder, but to make their path easier. Since quantum tunneling is a probabilistic process, even small reductions in the energy barrier greatly increase the likelihood that electrons will pass through.
To ensure high performance, the team used atomic layer deposition, a precise fabrication method already common in the semiconductor industry. This allowed them to create extremely uniform titanium dioxide layers while avoiding tiny defects that can weaken devices, such as oxygen vacancies.
The result was a terahertz quantum device that operates reliably at electric fields of around 0.75 volts per nanometer. The device maintained stable performance for more than 1,000 operating cycles and successfully modulated terahertz signals by up to 60 percent—an impressive level of control at such high speeds.
Titanium dioxide also helped with heat management, further improving durability. According to Professor Lee, eliminating defects while maintaining excellent thermal properties was essential for achieving both stability and performance.
Professor Park said the team has now overcome the two biggest obstacles facing terahertz quantum devices: the need for high voltages and the risk of heat-related damage. With those barriers removed, the technology moves much closer to real-world use.
The breakthrough opens the door to ultra-fast, energy-efficient communication systems beyond 6G, as well as advanced applications such as quantum sensing and high-speed optical signal processing. As demand for faster and more efficient data technologies grows, devices like this could help define the next era of communication.
Source: KSR.
