"AI Eye" Pierces Fog and Night... Low-Cost Infrared Sensor Changes the Game [Reading Science]

Development of SWIR Image Sensor for Autonomous Driving
by Combining Quantum Dots and Two-Dimensional Semiconductors

A next-generation infrared image sensor technology capable of clearly recognizing objects even in fog, smoke, and nighttime environments has been developed in Korea. By presenting a platform that overcomes the limitations of existing high-cost compound semiconductor-based sensors and enables low-cost, large-area processing, this technology is drawing attention as a potential game-changer in the 'AI eye' race within the autonomous vehicle, robotics, security, and medical imaging markets.

On April 9, Daegu Gyeongbuk Institute of Science and Technology (DGIST) announced that the research team led by Professor Lee Jongsu of the Department of Energy Science and Engineering at DGIST, in collaboration with the team led by Principal Researcher Park Minchul of Korea Institute of Science and Technology (KIST) and the team led by Principal Researcher Kim Yonghun of Korea Institute of Materials Science (KIMS), has developed a next-generation near-infrared image sensor technology by combining quantum dots with two-dimensional semiconductors.

Conceptual diagram, optical properties, and bandgap alignment of 0D-2D hybrid devices. (a~c) Conceptual diagram, optical properties, and TEM images of the hybrid devices. (d~j) Operating principle of the hybrid photodetector and effects of the hybrid interface. Provided by the research team

Short-wave infrared (SWIR) sensors are considered core components for autonomous vehicles, robotics, night surveillance, and medical imaging, as they can clearly recognize objects not only during the day and night but also in fog or smoke. However, the current reliance on expensive compound semiconductors such as indium gallium arsenide (InGaAs) has resulted in high prices and difficulties in producing large-area sensors.

The research team implemented a hybrid photosensor structure combining silver-tellurium (Ag₂Te)-based quantum dots, which have a high infrared absorption rate, with molybdenum disulfide (MoS₂) two-dimensional semiconductors, known for fast charge mobility. This design maximizes the advantages of each material, with the two-dimensional semiconductor compensating for the slow charge transport of the quantum dots.

In particular, by utilizing the photodoping effect that occurs at the interface between the two materials, the team succeeded in greatly amplifying the optical signal. The developed sensor demonstrated high sensitivity and detection performance sufficient to rapidly and accurately capture even extremely weak infrared signals. The photoresponsivity reached 7.5×10⁵ A/W, and the detectivity was at the level of 10¹³ Jones.

Research team photo. From the left: DGIST (Jongsu Lee, Seokjin Jung), KIST (Mincheol Park, Hyunwoo Ko, Suyeon Cho), KIMS (Yonghoon Kim), Kyungpook National University (Hyunsu Na) joint research team. Courtesy of DGIST

The research team went beyond a single device and successfully fabricated a 32×32 pixel infrared image sensor array, achieving actual image measurement. When combined with existing CMOS semiconductor processes, this technology could quickly be expanded into low-cost, large-area next-generation SWIR cameras. In fact, at the prototype sensor level, technological expansion is expected within the next two years.

Professor Lee Jongsu of DGIST stated, "By combining the high optical absorption of quantum dots and the fast charge transport of two-dimensional semiconductors, we have overcome the fundamental limitations of conventional infrared sensors," adding, "This will become a core foundational technology for high-resolution infrared cameras and next-generation intelligent optical sensor systems."

The results of this research were published in the March issue of the international journal Advanced Materials in the field of materials science.

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