Korea University Research Team Develops Core Technology for Ultra-Low Noise Infrared Quantum Dot Photodetectors

Professor Sim Jaewon and Professor Oh Seungjoo Team

Researchers at Korea University have developed a core technology for an ultra-low-noise infrared quantum dot photodetector using a polymer optical shielding layer.

From the top left clockwise: Jaewon Shim, Professor of Electrical and Electronic Engineering (Corresponding Author), Seungjoo Oh, Professor of Materials Science and Engineering (Corresponding Author), Youngkyun Choi, Master's and Doctoral Student (First Author), Taehyuk Kim, Master's and Doctoral Student (First Author) [Image Source=Korea University]

The research team led by Professor Shim Jae-won from the Department of Electrical and Electronic Engineering at Korea University College of Engineering (first author Kim Tae-hyuk, MS/PhD course) and Professor Oh Seung-joo from the Department of Materials Science and Engineering (first author Choi Young-gun, MS/PhD course) recently published their findings online in the world-renowned journal in the field, Advanced Materials (IF: 29.4).

With the emergence of energy-efficient and compact Internet of Things (IoT) applications, interest in optoelectronic systems is growing. Among these, quantum dot photodetectors (Qunatum dot Photodetector, QPD) play a pivotal role in selective near-infrared (Near-Infrared, NIR) detection required for remote sensing, deep tissue penetration, and specific molecular absorption due to their high optical sensitivity.

Among existing NIR photodetectors, silicon photodetectors exhibit excellent responsiveness and compatibility but face difficulties detecting wavelengths above 1000 nm and have limitations in selective NIR detection. An alternative, Indium gallium arsenide (InGaAs) photodetectors, also show superior characteristics in the NIR region; however, they have fundamental limitations due to high noise current from epitaxial growth on indium phosphide (InP) substrates, complex processes such as flip-chip bonding for integration with external readout integrated circuits (ROIC), and high costs.

To address these fundamental issues, the Korea University research team successfully developed a device with selective NIR detection and extremely low noise by inserting a thick polymer optical shielding layer. The noise spectral density of this device was approximately ~10^-27 A²/Hz, achieving a high specific detectivity (Specific Detectivity, D*) of 1.31 × 10¹¹ Jones in the 980 nm wavelength band.

By embedding the polymer optical shielding layer inside the quantum dot semiconductor, the device enabled self-filtering technology that blocked unwanted visible light regions (450-750 nm), reducing the responsivity (Responsivity, R) in the visible light range by more than 92%. Additionally, this thick polymer layer suppressed internally generated currents caused by defects and thermal effects and provided a long hole transport path, potentially significantly reducing noise current.

This device overcame the high noise current limitations of narrow bandgap materials, representing the lowest noise level reported among quantum dot photodetectors to date. This achievement is evaluated as opening new possibilities contributing to next-generation remote monitoring, security, and selective tissue penetration technologies in the field of infrared quantum dot optoelectronic devices. Furthermore, the technology demonstrated potential economic feasibility and broad adoption possibilities through cost-effective and simple process techniques.

This research was conducted with support from the Korea Research Foundation’s Mid-career Research Program and Science and Engineering Mid-career Researcher Support Program, as well as the Ministry of Trade, Industry and Energy’s Technology Innovation Program.