WSe₂/MoS₂ van der Waals Heterostructures Decorated with Au Nanoparticles for Broadband Plasmonic Photodetectors

Surface plasmons of metal nanostructures can resonantly enhance the light absorption of two-dimensional (2D) materials and stacked van der Waals (vdW) heterostructure-based photodetectors, realizing the improvement of responsivity. So far, it has remained challenging to control and tune surface plasmons via artificially varying the geometry of arrayed metal nanostructures. Here, we demonstrate a broadband plasmonic photodetector based on an integration of gold nanoparticles (Au NPs) on a WSe₂/MoS₂ vdW heterostructure. The plasmon resonance peaks could be tuned by the artificially patterning of Au NPs with the geometry controlled by a rapid thermal processing technique and enable a great improvement of light absorption crossing broadband spectral regimes from 400 to 1100 nm. Our device operates at room temperature and exhibits the highest responsivity of up to 1948 mA W^–1, detectivity of 7.2 × 10¹¹ cm Hz^1/2 W^–1, and the ultrafast response of 8.3 μs under an illumination with zero-bias voltage. These merits of high-performance detection and rapidly scalable production of controlled metal nanostructures, with the development of 2D material synthesis and transfer techniques, offer great potential for large-area and smart fabrication of nanoscale optoelectronic devices with low power consumption.