Kyungpook National University Professor Daehyun Kim’s Team Achieves World’s First 700 GHz Frequency Breakthrough in Gallium Nitride Electronic Devices

Research Results Unveiled at One of the World's Top Three Semiconductor Conferences

The research team led by Professor Daehyun Kim from the Department of Electronic Engineering at Kyungpook National University has developed a 45-nanometer (nm) class gallium nitride (GaN) high electron mobility transistor (HEMT) that achieved a record maximum oscillation frequency (fmax) of 742 GHz.

This marks the first time in the world that a GaN high electron mobility transistor has surpassed a maximum oscillation frequency of 700 GHz.

(From left) Ingkeun Lee, Postdoctoral Researcher at the Semiconductor Convergence Technology Institute, Kyungpook National University (contributing author), Wansu Park, PhD Candidate in the Department of Electronic Engineering, Kyungpook National University (first author), Daehyun Kim, Professor in the Department of Electronic Engineering, Kyungpook National University (corresponding author). Provided by Kyungpook National University

The results of this research were released on June 18 (local time in the United States) at the 'VLSI Symposium 2026,' an international academic conference on semiconductors held in Honolulu, Hawaii.

The VLSI Symposium is recognized as one of the world’s top three semiconductor conferences and is regarded as a leading international conference in the field of advanced semiconductor devices and circuit technology.

GaN semiconductors have attracted attention in the high-power radio frequency (RF) semiconductor sector due to their outstanding material properties.

However, the ultra-high-frequency domain near terahertz has been dominated by indium phosphide (InP)-based devices, while GaN devices have been considered to have limitations for ultra-high-frequency applications due to lower frequency characteristics.

Professor Kim’s team overcame these limitations by applying an ultra-fine gate process with a 45nm gate length and a 'selective n+ GaN regrowth technology' that reduces contact resistance in the source and drain regions.

The GaN HEMT developed through this approach achieved an fmax of 742 GHz, which is the first instance of a GaN transistor exceeding 700 GHz for fmax.

Additionally, the device achieved a comprehensive performance index (favg) of 497 GHz, which reflects both the cutoff frequency (fT) and fmax, thereby setting a new standard for GaN-based ultra-high-frequency electronic device technology.

Professor Daehyun Kim of Kyungpook National University commented, "This research is significant as it is a representative achievement of industry-academia collaboration, combining the compound semiconductor device fabrication line at QnC Solution & Advanced Innovation (QSI), a joint research institution, with the university’s expertise in device and circuit research. Based on these results, we plan to further accelerate next-generation GaN electronic device research targeting the sub-terahertz frequency bands for 6G and K-Defense applications."

This research was supported by the Samsung Future Technology Development Program and the Civil-Military Dual-Use Technology Development Program, and was jointly conducted by Kyungpook National University, QnC Solution & Advanced Innovation (QSI), Electronics and Telecommunications Research Institute (ETRI), IVWorks, KAIST, and Texas Tech University in the United States.

This content was produced with the assistance of AI translation services.