High‐Performance Broadband Visible−Near Infrared Photodetector Enabled by Atomic Capping Layer

Abstract This study employs an effective oxygen (O₂) plasma treatment to fabricate multilayer molybdenum diselenide (MoSe₂) photodetectors for visible and near‐infrared (NIR) detection. With the introduction of O₂ plasma treatment, the atomic oxidized layer is generated to prevent direct interaction from O₂ and water (H₂0) molecules in air, leading to an improved environmental stability. Meanwhile, bonded O atoms provide an electron‐rich atmosphere, which can effectively reduce the intrinsic Se vacancies and generate a strong built‐in electric field to suppress the recombination of photocarriers. As a result, the O₂‐modified MoSe₂ photodetector exhibits an excellent photoresponse, including a high responsivity of 889 mA W⁻¹, a fast response time of 52 µs, and a high specific detectivity approaching 3.37 × 10¹⁴ Jones under 520 nm illumination with a light intensity of 2.02 mW cm⁻² at 0.5 V. Moreover, the response spectra of MoSe₂‐O₂ photodetectors can be further extended to NIR region (λ = 980 nm), owing to perturbation of O atoms in the Se−Mo sublattice. Ultimately, a turbidity detection system based on the optimized photodetector is demonstrated, which illustrates an accurate turbidity measurement with the concentration ranging from 0 to 4000 NTU.