□ A research team led by Prof. Hyuk-Jun Kwon of the Department of Electrical Engineering and Computer Science at DGIST (President Kunwoo Lee) has developed a technology that directly forms a junction structure within a two-dimensional (2D) semiconductor using a laser to enhance photodetection performance. Their study developed a process technology that can achieve high-performance photodetectors through a single laser process without requiring additional stacking or transfer processes. This process is expected to contribute to the development of next-generation flexible sensors, image sensors, and integrated optoelectronic devices.
□ A photodetector is a key device that converts light into electrical signals and is widely used in image sensors, optical communication, the Internet of Things (IoT), and flexible sensors. In particular, 2D semiconductors are promising as next-generation materials owing to their atomic-layer thickness and flexibility. However, conventional junction devices have typically relied on methods involving the layer-by-layer stacking or transfer of different materials. They have limitations such as complex fabrication processes and the likelihood of contamination or defects during the process.
□ To address these issues, the research team proposed a process in which a laser is directly applied to a single 2D material, tin disulfide (SnS₂), to create junctions only at desired locations. This process can be performed simply under ambient conditions, and the laser-irradiated regions undergo changes in properties as they become thinner and bond with oxygen. Consequently, an “energy barrier,” which effectively separates photo-generated charges, is naturally formed between the laser-treated and untreated regions.
□ The resulting energy barrier rapidly separates the positively and negatively charged carriers generated by light and suppresses their recombination and the resulting loss of the electrical signal. The photodetector fabricated by the research team exhibited response speeds more than tens of times faster than those of conventional approaches while also demonstrating outstanding performance in both photoelectric conversion efficiency (a responsivity of 703 mA W⁻¹ and an external quantum efficiency of 170%) and the ability to detect weak light (detectivity of 2.35 × 10¹⁴ Jones). The team also confirmed stability in which the performance is maintained even after repeated measurements.
□ “This study demonstrates that an optimal environment for converting light into electricity can be directly created within a two-dimensional semiconductor using only a laser, without requiring complex fabrication processes,” stated Prof. Hyuk-Jun Kwon. “This technology is expected to become a practical process technology that can be extended not only to high-performance photodetectors, but also to various industrial sectors, such as large-area image sensors and transparent, flexible photosensors.”
□ Meanwhile, the study was conducted with an integrated master’s–doctoral student Jieun Lee serving as the first author and Prof. Hyuk-Jun Kwon participating as the corresponding author. The research findings were published in the May 2026 issue of Advanced Optical Materials , a world-renowned journal in the field of optics (ranked within the top 8% of the JCR category). This research was supported by the Ministry of Science and ICT’s Individual Basic Research Program (Mid-Career) and the InnoCORE Program, as well as the Ministry of Education’s Priority Research Centers Program.
Advanced Optical Materials
Laser-Induced Oxygen Engineering for Localized Homojunction Formation in SnS₂ Photodetectors
8-May-2026