Jeonbuk National University (JBNU) Division of Electronics and Information Engineering master's student Seoeunji Seo (supervising Professor Ki-Hyun Kim)'s research on a high-performance ammonia (NH3) gas sensor has been published in ACS Sensors, a globally leading journal in the field of sensors. This journal, published by the American Chemical Society (ACS), is a top-tier SCI(E) journal and is highly influential in the fields of sensor materials, devices, systems, and applied technologies.

This study developed a heterojunction-based high-sensitivity, low-power ammonia gas sensor by integrating a silicon-based p–n junction diode structure with single-walled carbon nanotubes (SWCNT), gold nanoparticles (AuNP), and zinc oxide (ZnO).

Ammonia is an important analyte in various fields including industrial workplaces, environmental monitoring, indoor air quality management, and medical diagnostics. However, conventional metal-oxide-based sensors have shown limitations for practical applications due to high operating temperatures and power consumption.

The research team simultaneously applied carboxyl (–COOH) functionalization on the carbon nanotube surface, the catalytic effect of gold nanoparticles, and the ZnO heterojunction structure to achieve dramatically improved performance compared to existing sensors. The developed sensor exhibited a high response of 1,128% to 30 ppm ammonia at room temperature and demonstrated detection down to the 69 ppb level. It also maintained stable detection characteristics under high relative humidity, confirming its applicability in real-field environments.

Notably, the study not only improved performance but also systematically elucidated the sensor's operating principle through TCAD (Technology Computer-Aided Design) simulations. The team revealed that charge transfer and changes in the energy barrier at the ZnO–carbon nanotube interface are the key factors enhancing sensitivity, thereby scientifically validating the sensor's physical mechanism.

This achievement is expected to have significant ripple effects not only in the sensor-semiconductor industry but also in livestock environment management. Sensor semiconductors are core components for implementing Physical AI, providing the foundational technology to sense and process diverse information from the real world. The developed sensor can operate with low power and is compatible with semiconductor-process-based fabrication, which may contribute to next-generation advanced sensors and strengthen competitiveness in the sensor-semiconductor industry.

In addition, ammonia is a representative malodorous compound emitted from livestock farms and a major precursor of fine particulate matter. Therefore, this sensor has strong potential for real-time ammonia detection technologies in applications such as livestock odor reduction, smart barns, and environmental monitoring systems. Further expansion is anticipated into areas including IoT environmental sensors, smart factories, industrial safety monitoring, and electronic-nose systems.

Professor Ki-Hyun Kim stated, "This research fused nanomaterials, semiconductor devices, and sensor system technologies to achieve world-class ammonia detection performance. We will further develop this into smart sensor technologies applicable to livestock odor monitoring, environmental management, and industrial safety, contributing to nurturing the sensor-semiconductor industry in the Jeonbuk region and enhancing the competitiveness of local companies."

Meanwhile, this research was conducted with support from the National Research Foundation of Korea (NRF) Excellent Early-Career Research Program, the Institute for Information & Communications Technology Planning and Evaluation (IITP) Regional Intelligent Innovation Talent Development Program, the 4th phase BK21 project (BK21 FOUR), and the Glocal University 30 project 'University-Industry-City Triangle (JUIC Triangle)'.