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<p>Heterostructure-based photodetectors often face performance limitations due to strong interlayer coupling and restricted band modulation. An alternative approach is engineering doped 2D TMDs, particularly through hole doping, to achieve tunable electronic and optoelectronic properties. In this work, we report oxygen passivation of selenium vacancies in MoSe<sub>2</sub> (O<sub>P</sub>-MoSe<sub>2</sub>) and compare it with vacancy-rich MoSe<sub>2</sub> (V<sub>Se</sub>-MoSe<sub>2</sub>) in terms of structural, chemical, and optoelectronic characteristics, demonstrating its application in weak-light photodetection. Raman spectroscopy, PL spectroscopy, and X-ray photoelectron spectroscopy confirm that oxygen passivation improves structural quality and optical performance. Low-temperature PL reveals reduced inhomogeneous broadening and biexcitonic features, indicating modulation of excitonic interactions. First-principles calculations show oxygen preferentially occupies vacancy sites, effectively passivating them and suppressing defect-related states. Consequently, O<sub>P</sub>-MoSe<sub>2</sub> photodetectors achieve outstanding performance under 530 nm illumination, with responsivity of 0.74 × 10<sup>5 </sup>A/W, detectivity of ~10<sup>14</sup> Jones, at 89 nW/cm<sup>2</sup>, and a low noise-equivalent power of 0.087 fW/Hz<sup>1/2</sup>. Furthermore, we demonstrate weak-light tracking of moving objects at varying speeds, mimicking security surveillance conditions. These results establish oxygen-passivated MoSe<sub>2</sub> as a promising platform for high-performance, low-light photodetection. This work underscores oxygen passivation as an effective defect engineering strategy for high-performance, ultra-sensitive 2D photodetectors.</p>

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Oxygen passivation driven defect states healing in monolayer MoSe2 for ultra-high photoresponsivity

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月17日

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  • Shubham Yadav,
  • Mario Flores Salazar,
  • Hardeep,
  • Keerthana S. Kumar,
  • Ana K. Rocha Robledo,
  • Amogh Ashok,
  • Chandra Sekhar Reddy Kolli,
  • Afkham Mir,
  • Akshay Singh,
  • Andres de Luna Bugallo,
  • Parikshit Sahatiya

摘要

Heterostructure-based photodetectors often face performance limitations due to strong interlayer coupling and restricted band modulation. An alternative approach is engineering doped 2D TMDs, particularly through hole doping, to achieve tunable electronic and optoelectronic properties. In this work, we report oxygen passivation of selenium vacancies in MoSe2 (OP-MoSe2) and compare it with vacancy-rich MoSe2 (VSe-MoSe2) in terms of structural, chemical, and optoelectronic characteristics, demonstrating its application in weak-light photodetection. Raman spectroscopy, PL spectroscopy, and X-ray photoelectron spectroscopy confirm that oxygen passivation improves structural quality and optical performance. Low-temperature PL reveals reduced inhomogeneous broadening and biexcitonic features, indicating modulation of excitonic interactions. First-principles calculations show oxygen preferentially occupies vacancy sites, effectively passivating them and suppressing defect-related states. Consequently, OP-MoSe2 photodetectors achieve outstanding performance under 530 nm illumination, with responsivity of 0.74 × 105 A/W, detectivity of ~1014 Jones, at 89 nW/cm2, and a low noise-equivalent power of 0.087 fW/Hz1/2. Furthermore, we demonstrate weak-light tracking of moving objects at varying speeds, mimicking security surveillance conditions. These results establish oxygen-passivated MoSe2 as a promising platform for high-performance, low-light photodetection. This work underscores oxygen passivation as an effective defect engineering strategy for high-performance, ultra-sensitive 2D photodetectors.