Recently, the team of Weimin Liu of the Chinese Academy of Sciences and Weihong Qi of Northwestern Polytechnical University published a study.
Two-dimensional molybdenum disulfide (MoS2) is a promising material for optoelectronic applications including photodetectors, owing to properties like high carrier mobility, strong light absorption, and tunable bandgap. Introducing sulfur vacancies in MoS2 can enhance broadband photodetection performance by narrowing the bandgap and creating defect states. However, sulfur vacancies can also lead to slower photoresponse speeds due to carrier trapping. Transition metal nanoparticles like nickel (Ni) can interact with MoS2, but the potential for Ni nanoparticles to improve the photodetection ability of MoS2 has not been explored. This work aimed to develop a MoS2-based photodetector with enhanced responsivity across visible and near-infrared wavelengths, as well as faster photoresponse speeds, through defect engineering and Ni nanoparticle decoration. The nanocomposite strategy was intended to overcome issues with using defect states in MoS2, enabling high-performance broadband photodetectors.
In summary, our work successfully enhanced optoelectronic performance by introducing S vacancies and incorporating Ni nanoparticles into a MoS2 multilayer photodetector. S vacancies enable effective NIR photodetection, and the photovoltaic effect causes electrons to flow into Ni nanoparticles, functioning as a negative-voltage gate. The resulting photogating effect suppresses trap-assisted recombination and enhances hole transport, optimizing sensitivity, responsivity, and response speed. This novel metal-semiconductor hybrid photodetector mechanism offers an alternative to LSPR, minimizing the unfavorable impact of defect engineering and enabling high-performance, broad-spectrum photodetection in MoS2-based optoelectronic devices.
The I–V curves of the MoS2 device.
The time-dependent photoresponse of the MoS2 device
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