A Korean research team has developed a high-performance sensor device using quantum dots that can amplify and detect extremely faint infrared light at room temperature. The technology is expected to find applications in autonomous vehicles, space observation, and quantum computing.
KAIST announced on the 8th that a research team led by Professor Jung-Yong Lee of the School of Electrical Engineering has developed an 'avalanche electron multiplication technology' using colloidal quantum dots. This technology absorbs infrared photons (particles of light) and amplifies the resulting electrons 85-fold, achieving a sensor sensitivity 10 times higher than existing technologies. The research findings were published in the international journal 'Nature Nanotechnology' on the 18th of last month.
Sensors that amplify and detect infrared photons play a crucial role in various advanced technologies, including LiDAR, which serves as the "eyes" for autonomous vehicles, and the measurement of qubits, the fundamental unit of information in quantum computing.
Quantum dots—semiconductor materials shrunk to the nanometer (nm, one-billionth of a meter) scale—are gaining attention as a next-generation infrared sensor material for their ability to achieve high, selective detection efficiency in specific wavelength bands. A key advantage of quantum dot infrared sensors is that they are less affected by ambient temperature than conventional crystalline semiconductor-based sensors, allowing them to operate well at room temperature.
However, quantum dot infrared sensors have faced challenges such as low charge mobility and limited charge generation due to instabilities on the quantum dot surface. While recent research has focused on developing new materials to encapsulate quantum dots and improve sensor performance, their capabilities are still insufficient for applications in autonomous vehicles or quantum technology.
The research team applied a strong electric field to accelerate electrons, increasing their kinetic energy and causing them to generate additional electrons in adjacent quantum dots. They also determined that the distance between quantum dot particles must be optimally controlled to achieve this electron multiplication. Furthermore, they discovered that a quantum dot layer thicker than 540 nm is necessary to efficiently amplify electrons without introducing noise current.
The quantum dot infrared sensor device, incorporating these findings, demonstrated an 85-fold signal amplification when exposed to infrared light at room temperature and recorded a sensitivity tens of thousands of times higher than that of conventional infrared night vision systems.
Byung-Soo Kim, a researcher at the KAIST Research Institute for Information and Electronics and co-first author of the study, stated, "The quantum dot avalanche device represents a novel research field with no prior reports." He added, "This core technology could spearhead the development of venture companies that will lead the global markets for autonomous vehicles, quantum computing, and medical imaging."
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- doi.org/10.1038/s41565-024-01831-x
