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

This study employs an effective oxygen (O-2) plasma treatment to fabricate multilayer molybdenum diselenide (MoSe2) photodetectors for visible and near-infrared (NIR) detection. With the introduction of O-2 plasma treatment, the atomic oxidized layer is generated to prevent direct interaction from O-2 and water (H(2)0) 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 O-2-modified MoSe2 photodetector exhibits an excellent photoresponse, including a high responsivity of 889 mA W-1, a fast response time of 52 mu s, and a high specific detectivity approaching 3.37 x 10(14) 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-O-2 photodetectors can be further extended to NIR region (lambda = 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.