Extending Silicon Avalanche Photodetection Beyond 2 μm by Direct GeSn Integration
Abstract
Silicon avalanche photodiodes provide a technologically mature platform for sensitive photodetection, but their spectral response is intrinsically limited by the silicon bandgap. Extending their operation into the infrared requires the integration of narrow-bandgap absorbers while preserving efficient avalanche multiplication and compatibility with silicon processing. Here, we propose and demonstrate a monolithic approach that combines direct, buffer-free growth of GeSn on silicon with a lateral thin-junction separate-absorption-multiplication architecture. The GeSn layer, with a Sn composition reaching 6 at.%, extends optical absorption to a wavelength of 2.6 μm, while avalanche multiplication is spatially confined to an ion-implanted silicon lateral junction. This separation enables independent control of infrared absorption and carrier multiplication without the thick Ge virtual substrates conventionally used for GeSn epitaxy. GeSn-on-Si avalanche photodiodes exhibit low pre-breakdown dark current, stable breakdown at 72 V independent of device diameter, and clear infrared photoresponse extending beyond 2 μm. At 78 K, the devices exhibit external quantum efficiency exceeding 100%, reaching 163% at 1.55 μm, providing direct evidence of avalanche multiplication. These results establish direct integration of narrow-bandgap group-IV absorbers with silicon multiplication regions as a scalable strategy for extending the spectral reach of silicon avalanche photodetection, opening a route toward monolithic infrared detectors for sensing, imaging, communications, LiDAR, and quantum photonics
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BibTeX
@misc{atalla2026extending,
title = {{Extending Silicon Avalanche Photodetection Beyond $2~μ$m by Direct GeSn Integration}},
author = {M. R. M. Atalla and J. Bélec and E. Rahier and S. Koelling and K. Omambac and P. Daoust and S. Assali and O. Moutanabbir},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.27702},
eprint = {2608.27702},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.27702},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Extending Silicon Avalanche Photodetection Beyond 2 μm by Direct GeSn Integration
AU - M. R. M. Atalla
AU - J. Bélec
AU - E. Rahier
AU - S. Koelling
AU - K. Omambac
AU - P. Daoust
AU - S. Assali
AU - O. Moutanabbir
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2608.27702
UR - https://arxiv.org/abs/2608.27702
AB - Silicon avalanche photodiodes provide a technologically mature platform for sensitive photodetection, but their spectral response is intrinsically limited by the silicon bandgap. Extending their operation into the infrared requires the integration of narrow-bandgap absorbers while preserving efficient avalanche multiplication and compatibility with silicon processing. Here, we propose and demonstrate a monolithic approach that combines direct, buffer-free growth of GeSn on silicon with a lateral thin-junction separate-absorption-multiplication architecture. The GeSn layer, with a Sn composition reaching 6 at.%, extends optical absorption to a wavelength of 2.6 μm, while avalanche multiplication is spatially confined to an ion-implanted silicon lateral junction. This separation enables independent control of infrared absorption and carrier multiplication without the thick Ge virtual substrates conventionally used for GeSn epitaxy. GeSn-on-Si avalanche photodiodes exhibit low pre-breakdown dark current, stable breakdown at 72 V independent of device diameter, and clear infrared photoresponse extending beyond 2 μm. At 78 K, the devices exhibit external quantum efficiency exceeding 100%, reaching 163% at 1.55 μm, providing direct evidence of avalanche multiplication. These results establish direct integration of narrow-bandgap group-IV absorbers with silicon multiplication regions as a scalable strategy for extending the spectral reach of silicon avalanche photodetection, opening a route toward monolithic infrared detectors for sensing, imaging, communications, LiDAR, and quantum photonics
ER -