Pukyong National University

PKNU and Korea Institute of Science and Technology Develop Two-Dimensional Metal Electrode Technology to Accelerate Next-Generation AI Vision Sensor Implementation

- Research Achievement by Professor Ji-Soo Jang of Pukyong National University and Drs. Do-Kyung Hwang and Hyo-Won Moon of KIST

- Paper Published in International Journal  'Materials Science and Engineering R: Reports'

A joint research team from Pukyong National University and the Korea Institute of Science and Technology (KIST) has identified two-dimensional (2D) metal electrodes as a key factor determining the performance of next generation 2D semiconductor devices. Leveraging this discovery, the team successfully demonstrated both high-performance optoelectronic devices and In-sensor computing functionality.

The findings are expected to provide a new technological pathway toward the realization of next-generation artificial intelligence (AI) vision sensors, which are designed to capture and process visual information in a manner similar to the human visual system.

A joint research team consisting of Professor Ji-Soo Jang of the Department of Display and Semiconductor Engineering at Pukyong National University, and Dr. Do-Kyung Hwang (a faculty-affiliated professor at the KU-KIST Graduate School of Converging Science and Technology, Korea University) and Dr. Hyo-Won Moon of the Quantum Technology Research Center, Center for Next-Generation Semiconductor Research, Korea Institute of Science and Technology (KIST), has developed a technology for designing a new optoelectronic device architecture utilizing two-dimensional (2D) metal electrodes. The research findings were published online on June 1 in a leading international journal in the field of materials science, Advanced Materials  'Materials Science and Engineering R: Reports' (IF=26.8).

Two-dimensional semiconductors are emerging materials composed of ultrathin structures, only a few atomic layers thick and are considered promising candidates for applications in next-generation low-power electronic devices and artificial intelligence vision systems. However, defects formed at the interface where 2D semiconductors come into contact with electrodes, along with the phenomenon known as Fermi-level pinning, have long been recognized as major obstacles limiting device performance.

To overcome these limitations, the research team designed a variety of optoelectronic device architectures incorporating different two-dimensional metal electrodes and systematically compared and analyzed how electrode characteristics influence optoelectronic performance.

The study demonstrated that, unlike conventional bulk metal electrodes, 2D metal electrodes do not damage the surface of 2D semiconductors and instead form an almost defect-free, ideal interface. Furthermore, through photoluminescence measurements and temperature-dependent electrical characterization, the researchers confirmed that both interface defects and Fermi-level pinning effects between the 2D metal electrodes and WS₂ (tungsten disulfide) semiconductor were effectively suppressed.

In addition, by applying various types of 2D metal electrodes to optoelectronic devices and conducting systematic experiments, the researchers identified the work function of the electrode as a critical factor governing photodetection performance. In particular, when chlorine (Cl)-doped two-dimensional tin diselenide (Cl-SnSe₂), a 2D metal with a high work function, was used as the electrode material, the photodetector achieved outstanding performance, exhibiting a linear dynamic range (LDR) of 135 dB and a power conversion efficiency (PCE) of 13.6%.

Building on these results, the team further demonstrated In-sensor Computing, a technology that enables image information to be processed directly within the sensor itself, using the newly developed high-efficiency optoelectronic devices. Experimental results showed that devices employing 2D metal electrodes delivered significantly superior image-processing capabilities compared with conventional devices based on traditional bulk metal electrodes.

Professor Ji-Soo Jang, the principal investigator of the study, stated, “This research systematically demonstrates how the work function of two-dimensional metal electrodes determines the optoelectronic characteristics of devices. We expect the findings to be widely applicable to a range of future technologies, including artificial intelligence vision systems, next-generation low-power optical sensors, and edge computing platforms.”

Meanwhile, the research was supported by the New Faculty Research Grant Program of Pukyong National University, as well as the KIST Institutional Program and the Mid-Career Researcher Program funded by the Ministry of Science and ICT.