Room temperature operation of germanium–silicon single-photon avalanche diode

• Published in: Nature (London) Vol. 627; no. 8003; pp. 295 - 300
• Main Authors: Na, Neil, Lu, Yen-Cheng, Liu, Yu-Hsuan, Chen, Po-Wei, Lai, Ying-Chen, Lin, You-Ru, Lin, Chung-Chih, Shia, Tim, Cheng, Chih-Hao, Chen, Shu-Lu
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.03.2024; Nature Publishing Group
• Subjects: 639/624/1075/401; 639/624/399/1099; Avalanche diodes; CMOS; Consumer electronics; Cryogenic temperature; Electric fields; Fabrication; Germanium; Humanities and Social Sciences; Incompatibility; Integrated circuits; multidisciplinary; Photon avalanches; Photons; Room temperature; Science; Science (multidisciplinary); Sensors; Silicon; Temperature; Timing jitter; Wavelength; Wavelengths
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-024-07076-x

The ability to detect single photons has led to the advancement of numerous research fields 1 – 11 . Although various types of single-photon detector have been developed 12 , because of two main factors—that is, (1) the need for operating at cryogenic temperature 13 , 14 and (2) the incompatibility with complementary metal–oxide–semiconductor (CMOS) fabrication processes 15 , 16 —so far, to our knowledge, only Si-based single-photon avalanche diode (SPAD) 17 , 18 has gained mainstream success and has been used in consumer electronics. With the growing demand to shift the operation wavelength from near-infrared to short-wavelength infrared (SWIR) for better safety and performance 19 – 21 , an alternative solution is required because Si has negligible optical absorption for wavelengths beyond 1 µm. Here we report a CMOS-compatible, high-performing germanium–silicon SPAD operated at room temperature, featuring a noise-equivalent power improvement over the previous Ge-based SPADs 22 – 28 by 2–3.5 orders of magnitude. Key parameters such as dark count rate, single-photon detection probability at 1,310 nm, timing jitter, after-pulsing characteristic time and after-pulsing probability are, respectively, measured as 19 kHz µm −2 , 12%, 188 ps, ~90 ns and <1%, with a low breakdown voltage of 10.26 V and a small excess bias of 0.75 V. Three-dimensional point-cloud images are captured with direct time-of-flight technique as proof of concept. This work paves the way towards using single-photon-sensitive SWIR sensors, imagers and photonic integrated circuits in everyday life. A germanium–silicon single-photon avalanche diode operated at room temperature shows a noise-equivalent power improvement over the previous Ge-based single-photon avalanche diodes by 2–3.5 orders of magnitude.