Improved Optoelectronic Performance of MoS₂ Photodetector via Localized Surface Plasmon Resonance Coupling of Double-Layered Au Nanoparticles with Sandwich Structure

Two-dimensional (2D) MoS2 has received much research interest because of its outstanding optical and electronic characteristics and is regarded as one of the most prospective semiconductors for application in future optoelectronic devices. Nevertheless, the low visible light absorption capacity and the long photoresponse time restrict its practical application in the field of photodetectors. Therefore, optoelectronic performance of 2D MoS2 needs to be further improved. In this study, a MoS2 flake modified by double-layered Au nanoparticles (NPs) with sandwich structure (Au–MoS2–Au) photodetector is designed and fabricated for the sensitive detection of visible light. Benefiting from the enhanced local surface plasmon resonance (LSPR) coupling between the upper and lower layers of Au NPs deposited on both sides of few-layered MoS2, double-layered Au NPs with sandwich structure is able to enhance visible light absorption and local electric field of MoS2. Accordingly, the optoelectronic performance of the Au–MoS2–Au photodetector is superior to that of MoS2 modified with single-layered Au NPs. The peak photoresponsivity and specific detectivity of the Au–MoS2–Au photodetector are as high as 1757 A/W and 3.44 × 1010 Jones, respectively. The response speed is estimated to be less than 24 ms. The present research may contribute to the development of a promising approach toward the design and fabrication of high-performance devices via LSPR coupling of double-layered metal NPs with sandwich structure.