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

Nature volume 627, pages 295–300 (2024)Cite this article

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Abstract

The ability to detect single photons has led to the advancement of numerous research fields1,2,3,4,5,6,7,8,9,10,11. Although various types of single-photon detector have been developed12, because of two main factors—that is, (1) the need for operating at cryogenic temperature13,14 and (2) the incompatibility with complementary metal–oxide–semiconductor (CMOS) fabrication processes15,16—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 performance19,20,21, 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 SPADs22,23,24,25,26,27,28 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.

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Fig. 1: NEP and operation temperature of the previously reported Ge-based22,23,24,25,26,27,28 and InGaAs-based15,16 SPADs.
Fig. 2: Cross-sectional schematic concept, SEM image and I–V characteristics of the demonstrated GeSi SPAD.
Fig. 3: Counting properties of the demonstrated GeSi SPAD.
Fig. 4: Experimental demonstration of 3D scanning and imaging.

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Data availability

The data supporting this work are available in the main text, figures and Methods. Further information is available from the corresponding author.

Code availability

The codes supporting this work are for extracting the data from the equipment and plotting the data in figures. Further information is available from the corresponding author.

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Acknowledgements

We thank C. H. Shen and D. Y. Lai for the discussion on the fabrication equipment, process and metrology.

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Authors and Affiliations

  1. Artilux Inc., Zhubei, Taiwan ROC

    Neil Na, Yen-Cheng Lu, Yu-Hsuan Liu, Po-Wei Chen, Ying-Chen Lai, You-Ru Lin, Chung-Chih Lin, Tim Shia, Chih-Hao Cheng & Shu-Lu Chen

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Contributions

N.N. conceived the design, supervised the project, and wrote the paper. Y.-C. Lu contributed to device simulation, layout synthesis and wafer-level data analysis. Y.-H.L. contributed to layout synthesis, process integration and wafer-level data analysis. P.-W.C. and Y.-C. Lai contributed to process integration and device fabrication. Y.-R.L. contributed to process integration and wafer-level data analysis. C.-C.L. contributed to wafer-level data collection and analysis. T.S. contributed to die-level data collection and analysis and 3D PCL image capture. C.-H.C. contributed to die-level data collection and analysis. S.-L.C. oversaw the project.

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Correspondence to Neil Na.

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All authors are shareholders of Artilux Inc., a start-up company that makes SWIR 2D/3D sensors, imagers and photonic integrated circuits.

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Extended Data Fig. 1

The schematic plot of the electrical and optical setups used in producing data shown in Figs. 3 and 4.

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Na, N., Lu, YC., Liu, YH. et al. Room temperature operation of germanium–silicon single-photon avalanche diode. Nature 627, 295–300 (2024). https://doi.org/10.1038/s41586-024-07076-x

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