Detecting infrared light is critical in an enormous range of technologies, from remote controls to autofocus systems to self-driving cars and virtual reality headsets. That means there would be major benefits from improving the efficiency of infrared sensors, such as photodiodes.
Researchers at Aalto University have developed a new type of infrared photodiode that is 35% more responsive at 1.55 µm, the key wavelength for telecommunications, compared to other germanium-based components. Importantly, this new device can be manufactured using current production techniques, making it highly practical for adoption.
‘It took us eight years from the idea to proof-of-concept,’ says Hele Savin, a professor at Aalto University.
The basic idea is to make the photodiodes using germanium instead of indium gallium arsenide. Germanium photodiodes are cheaper and already fully compatible with the semiconductor manufacturing process – but so far, germanium photodiodes have performed poorly in terms of capturing infrared light.
Savin’s team managed to make germanium photodiodes that capture nearly all the infrared light that hits them.
Published paper:
Liu, H., Pasanen, T. P., Fung, T. H., Isometsä, J., Haarahiltunen, A., Hesse, S., … & Savin, H. (2025). Near-infrared germanium PIN-photodiodes with> 1A/W responsivity. Light: Science & Applications, 14(1), 9.
Link to the publication.
About Aalto University
AALTO University is a multidisciplinary university in the fields of Science and Technology, Economics, Architecture, and Art and Design. It has 409 faculty members and a student body of 20,000, 70% of which are students in Science and Technology. AALTO University was founded in 2010 by merging three Finnish universities: The Helsinki School of Economics, The University of Art and Design Helsinki, and Helsinki University of Technology. The three schools are all leading institutions in their respective fields and in their own right. Aalto University is a multidisciplinary community where Science and Art meet Technology and Business. The university is committed to identifying and solving grand societal challenges and building an innovative future.
Detecting infrared light is critical in an enormous range of technologies, from remote controls to autofocus systems to self-driving cars and virtual reality headsets. That means there would be major benefits from improving the efficiency of infrared sensors, such as photodiodes. Researchers at Aalto University have developed a new type of infrared photodiode that is […]
