Surface plasmon enhancement in different spatial distributions of nanowires and two-dimensional materials

Abstract

Surface plasmon (SP) nanostructures have been widely researched to improve the low light absorption of two-dimensional transition metal dichalcogenides (TMDCs). However, the impact of their different coupling forms, which is essential for the optimization of nanostructures, has been rarely investigated. Here, we construct two different spatially distributed composite structures of Ag nanowires (NWs) and monolayer (1L) molybdenum disulfide (MoS₂). When the Ag NW was buried under 1L MoS₂, the formed tiny optical cavity can further promote the light utilization of 1L MoS₂, so that the spectral enhancement by SP was stronger than that when the Ag NW was placed on the top of 1L MoS₂. In addition, the photoresponsivity and light response speed of the phototransistor based on the composite structure with Ag NWs buried underneath were improved by ∼5-fold and ∼1000-fold, respectively, compared to those of the pristine 1L MoS₂ phototransistor. This research provides a reference for the optimization of SP nanostructures to enhance the optoelectronic properties of two-dimensional materials.