Surface plasmon enhancement in silver nanowires and bilayer two-dimensional materials

Abstract

In order to improve the low light absorption of two-dimensional (2D) transition metal dichalcogenides (TMDCs), surface plasmon (SP) nanostructures have been widely studied. However, the impact of interlayer twist on such nanostructures has rarely been studied. Here, we construct two different composite structures of silver nanowires (Ag NWs) and pristine bilayer MoS₂ (pBLM) or twisted bilayer MoS₂ (tBLM). The interlayer twist can further promote the light utilization of MoS₂, resulting in an ∼4-fold higher spectral enhancement in Ag/tBLM than that in Ag/pBLM. In addition, the photocurrent and detectivity of the phototransistor based on the Ag/tBLM composite structure were improved by 7-fold and ∼100-fold, respectively, compared to those of the Ag/pBLM phototransistor. Theoretical simulations show that the enhancement of photocurrent can be attributed to the enhancement of the local electric field at the interface between Ag NWs and the tBLM film, which is called the ‘hot spot’. These results provide a reference for understanding the modulation mechanism of SPs and interlayer twist on the optoelectronic properties of 2D materials.