Photodetector handles light from visible to LWIR
A research team in South Korea has developed a next-generation sensor material capable of integrating the detection of multiple light wavelengths, from visible to LWIR, while maintaining stability under high-temperature and high-humidity. .
The joint team led by Wooseok Song at the Korea Research Institute of Chemical Technology (KRICT) and Dae Ho Yoon at Sungkyunkwan University used a topological crystalline insulator (TCI) derived from the 2D semiconductor SnSe with tellurium substitution.
As a quantum material, TCIs exhibit a narrow band gap, enabling detection of long-wavelength light such as MWIR and LWIR, while also maintaining high stability.
Unlike conventional 2D semiconductors that cannot detect low-energy photons due to a wide band gap, the TCI structure allows electrons to move freely on the surface states, enabling broadband and highly sensitive detection—including subtle LWIR thermal radiation such as that emitted by human fingers.
As a result, this new material achieves broadband detection over an ~8 times wider range (0.5–9.6 μm), compared to conventional 2D semiconductors (0.4–1.2 μm). It is also thin, lightweight, and highly stable under high temperature, humidity, and even underwater conditions.
Another key advantage is the simplified and low-cost fabrication process, according to the team. While traditional TCI synthesis required expensive ultra-high-vacuum equipment such as MBE, the research team designed SnSe0.9Te0.1 to retain topological properties while being less sensitive, enabling cost-efficient solution-based thermal decomposition synthesis. This allowed uniform production on a palm-sized 6-inch wafer, which is compatible with existing semiconductor processes, making it favourable for large-scale manufacturing.
The team is now extending this technology to 8-inch or larger wafers and integrating sensor arrays and circuits to develop complete sensor modules.
Wooseok Song explained, “This sensor can cover applications ranging from autonomous vehicles and military drones to smartwatches and home IoT security systems.”
KRICT president Young-Kuk Lee said, “This breakthrough will mark a turning point in replacing expensive imported broadband sensors and usher in an era of high-performance, domestically produced broadband sensors.”
Pictured above: First author Do Hyung Lee (left), corresponding author Wooseok Song (right) both from KRICT
Reference
Do Hyung Lee et al; ACS Nano 2025 19 (29)
