Sungkyunkwan University team finds synthesis mechanism of semiconductor nanocrystals

Jeong So-hee, second from left, associate professor at Sungkyunkwan University’s department of energy, poses with Maksym V. Kovalenko, third from left, chemistry professor at ETH Zurich in Switzerland, and other researchers at the university’s campus in Suwon, just south of Seoul. Courtesy of Sungkyunkwan University

A Sungkyunkwan University research team has identified the synthesis mechanism of next-generation infrared semiconductor nanocrystals, key materials for autonomous driving and smart sensors, the university said Thursday.

The mechanism was first discovered by a team led by Jeong So-hee, associate professor at the university’s department of energy, opening a new paradigm for semiconductor material design.

The findings illuminate the process of synthesizing infrared semiconductors known as III-V nanocrystals, which are extremely small semiconductor crystals made from elements in Groups III and V of the periodic table.

The university said the study tracked the reduction mechanism of heavy pnictogen elements, a process that had long been a mystery, adding that it is expected to accelerate the commercialization of high-performance infrared optoelectronic devices. A pnictogen refers to any chemical element in the nitrogen group, including nitrogen, phosphorus, arsenic and bismuth.

The research is drawing attention due to the growing importance of applying infrared-based technologies to areas such as nighttime self-driving and object recognition in smart home appliances.

Semiconductor materials capable of absorbing and emitting infrared light are essential to those advanced technologies, according to the university. However, many conventional materials contain toxic lead, raising concerns over environmental pollution and health risks.

Against this backdrop, III-V semiconductor nanocrystals have emerged as an alternative. Nevertheless, their fabrication processes are highly challenging and complex, making large-scale production and precise control difficult.

Jeong’s team adopted a “decoupling” strategy to solve the problem, separating pnictogen reduction from nanocrystal synthesis. Through experiments, the team discovered that a specific metal complex (metal-amide) gradually changes its properties when heated, thereby reducing and activating pnictogen precursors that serve as the source materials for semiconductors.

The team demonstrated that it is possible to prepare precursors with precisely controlled reactivity in advance by adjusting the temperature, and then use them for nanocrystal synthesis.

The findings were published Monday in the globally renowned Journal of the American Chemical Society, earning worldwide recognition for their academic significance.

The image shows schematic diagrams and graphs related to a study on the synthesis mechanism of next-generation infrared semiconductor nanocrystals published Monday in the Journal of the American Chemical Society (JACS). A Sungkyunkwan University research team led by Jeong So-hee, associate professor at the department of energy, conducted the study. Courtesy of Sungkyunkwan University

The university noted that the findings are likely to help South Korea secure a technological edge in producing the next-generation semiconductor materials.

“This research achievement represents a logical unraveling of the secret behind the mechanism of semiconductor synthesis hidden in the complex chemical reactions,” Jeong said.

She expressed hope that the study will serve as a compelling example of how the chemical principles taught in middle and high school can be applied to improve the performance of advanced technologies such as self-driving sensors and night vision cameras.

The research was conducted in close collaboration with a team led by Professor Maksym V. Kovalenko from the department of chemistry and applied biosciences at ETH Zurich in Switzerland. Kovalenko also serves as a scholar at the Nobel-Class Research Cooperation Center under the Sungkyunkwan Institute of Energy Science and Technology.

The study was carried out with strong support from the Ministry of Science and ICT, the National Research Foundation of Korea and Samsung Electronics.