Colloidal InSb Quantum Dots Mid-Wave Infrared Photoconductive Detectors via One-Step Strong Acid Surface Treatment Strategy.

Liu, Zifeng; Sun, Cong; Wang, Qingyu; Lu, Wanlong; Liu, Zhe; Li, Peixian; Chen, Yifan; Hu, Xingyu et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Colloidal InSb quantum dots (QDs) hold significant promise in infrared photodetection. However, the current InSb QDs suffer from poor carrier mobility and limited spectral response (<1.8 μm) due to complex surface structure and high sensitivity to hydrolysis and oxidation. Here, we demonstrate one-step strong acid surface treatment strategy to simultaneously replace native insulating ligands and eliminate surface indium oxide. This dual-functional strategy achieves efficient surface passivation and enhances charge carrier transport, enabling InSb QDs films to exhibit an unprecedented hole mobility of 1.4 cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup>. Notably, we report the first realization of a broadband InSb QDs infrared photoconductive detector with spectral sensitivity extending beyond 3 μm at room temperature. The device exhibits a specific detectivity of 4.7 × 10<sup>7</sup> Jones at 3.0 μm, representing the longest-wavelength interband photodetection based on lead/mercury-free QDs reported to date. This work manifests an important step toward room-temperature operable and heavy-metal-free QDs based mid-wave infrared photodetectors.