Reviewed by Lexie CornerJan 3 2025
Researchers at Aalto University have developed an infrared photodiode that is 35 % more responsive at 1.55 µm, a key wavelength for telecommunications, compared to other germanium-based components. The findings were published in Light: Science & Applications.
The new, more sensitive infrared sensor brings benefits to many different technologies. Image Credit: Aalto University / Xiaolong Liu
Infrared light detection is essential for technologies such as remote controls, autofocus systems, self-driving cars, and virtual reality headsets. Enhancing the efficiency of infrared sensors like photodiodes could bring significant benefits across these applications.
The new device is compatible with existing production methods, making it practical for widespread adoption.
It took us eight years from the idea to proof-of-concept.
Hele Savin, Professor, Aalto University
The fundamental concept is to create photodiodes using germanium rather than indium gallium arsenide. While germanium photodiodes are fully compatible with semiconductor manufacturing processes and are more cost-effective, their infrared light detection capabilities have historically been limited.
Savin's team successfully developed germanium photodiodes capable of capturing nearly all incident infrared light.
The high performance was made possible by combining several novel approaches: eliminating optical losses using surface nanostructures and minimizing electrical losses in two different ways.
Hanchen Liu, Doctoral Researcher, Aalto University
Experiments showed that the proof-of-concept photodiode outperformed both commercial indium gallium arsenide photodiodes and existing germanium photodiodes in responsiveness. The technology operates effectively across a wide range of wavelengths and captures infrared photons with high efficiency. The researchers expect the new photodiodes to integrate easily into various technologies and be readily manufactured using existing facilities.
The timing couldn’t be better. So many fields nowadays rely on sensing infrared radiation that the technology has become part of our everyday lives.
Hele Savin, Professor, Aalto University
Savin and the other team members are eager to see how their technology will impact current applications.
Journal Reference:
Liu, H., et al. (2024) Near-infrared germanium PIN-photodiodes with >1A/W responsivity. Light: Science & Applications. doi.org/10.1038/s41377-024-01670-4