Transistors in semiconductors function as a kind of "switch" that determines whether current flows or is blocked.

At this point, the voltage at which the switch turns on is called the "threshold voltage." If this voltage is too high, electrons do not flow well and devices become slow. If it is too low, unnecessary current leaks and power consumption increases. Therefore, how precisely the threshold voltage is controlled is a key technology that determines semiconductor performance.

A joint research team from Jeonbuk National University (JBNU) and Ajou University has developed a technology that can precisely adjust this "threshold voltage." The research is expected to become a core enabling technology for next-generation low-power semiconductors and flexible electronic systems.

JBNU Professor Taeuk Kim (Graduate School of Flexible Printed Electronics) and Ajou University Professor Seongjun Park (Department of Intelligent Semiconductor Engineering) and their research team announced on the 20th that they succeeded in precisely controlling the threshold voltage of oxide thin-film transistors using single-crystalline silver (Ag) nanosheets.

The study was led by JBNU researcher Hyunji Joo (Master's student, supervised by Professor Taeuk Kim) and was published in the latest 2025 issue of the world-leading materials science journal ACS Nano (IF=16.1, JCR top 6%) under the title "Scalable Integration of Single-Crystalline Ag Nanosheets for Threshold Voltage Engineering in Oxide Thin-Film Transistors."

The research team inserted silver nanosheets, which possess a single-crystalline (111) plane structure where Ag atoms are most stably arranged, between the semiconductor layer and the insulating layer of indium–gallium–zinc oxide (IGZO) transistors via an ultrasonic assembly process. These nanosheets play a central role in tuning the sensitivity of the current switch, and the threshold voltage can be finely adjusted according to the coverage of Ag nanosheets within the channel region.

Previously, complex processes were required to stably control the threshold voltage. However, the team's technique enables voltage control with a simple process under room temperature and atmospheric pressure conditions. It overcomes prior limitations by maintaining device performance (on/off current ratio, electron mobility) and stability.

In addition, the research team directly implemented an NMOS inverter circuit applying this technology, demonstrating that it can be broadly applied to various electronic devices and circuit design.

Professor Taeuk Kim stated, "This study precisely controlled a key semiconductor characteristic using single-crystalline metallic nanomaterials and a simple ultrasonic process. It will serve as an important foundational technology for the development of next-generation low-power semiconductors and flexible electronic systems."

Meanwhile, this research was carried out with support from the Ministry of Science and ICT's project "Development of van der Waals (vdW) Materials and Process Technologies for Ultra-High-Density Semiconductors" (Stacked van der Waals Semiconductor Project Group, headed by Professor Jae-Hyun Lee, Sungkyunkwan University) and the Korea Electric Power Corporation (KEPCO) Basic Research Program.