Waveguide-Integrated Bias-Free Graphene Mid-IR Photodetector and its Use for On-Chip Carbon Dioxide Gas Sensing

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🔬研究者:Novel waveguide-integrated graphene photodetector with zero-bias operation and mid-IR capability for gas sensing.

🏛政策担当者:Potential for enabling low-cost, compact CO2 sensors for emissions monitoring in industrial settings.

<title>Abstract</title> <p>Mid-infrared photonics offers strong potential for gas-sensing systems, yet waveguide-integrated photodetectors in mature platforms remain a key limitation. We address this challenge by integrating bias-free graphene photothermoelectric detectors with suspended silicon waveguides on a silicon photonics platform. By removing the buried oxide layer underneath the waveguides, we extend silicon photonics into the mid-infrared region. We achieved a propagation loss of 1.8 dB/cm at 4.2 µm, lower than previously reported losses for suspended silicon waveguides at this wavelength. The detectors feature a split-gate structure to electrostatically tune the graphene to form p-n junctions, thereby enhancing the photothermoelectric response, enabling zero-bias operation, and suppressing dark current and shot noise. We corroborate our experimental data with theoretical modeling and simulations. The detectors achieve responsivities of up to 1.54 V/W and noise-equivalent power of 27 nW/√Hz. Finally, we demonstrate on-chip room-temperature gas sensing of 10% CO2 with an estimated detection limit of 970 ppm.</p>

• Research Square https://doi.org/10.21203/rs.3.rs-9940821/v1first seen 2026-06-11 04:36:25 · last seen 2026-06-16 04:28:58