Manipulating the Exciton Dynamics in a MoS2/WS2 Heterobilayer with a Si/Au Nanocavity

Manipulating the exciton dynamics in a heterobilayer (HB) composed of two transition metal dichalcogenides (TMDCs) is important in the development of photonic/plasmonic devices based on TMDC HBs. Here, the realization of such a manipulation in a MoS2/WS2 HB is reported by using a Si/Au hybrid nanocavity composed of a Si nanoparticle and an Au film, which is manifested in the modification in the photoluminescence (PL) of the embedded MoS2/WS2 HB. It is shown that a transition from PL quenching to PL enhancement can be achieved by adjusting the diameter of the Si nanoparticle, which modifies the plasmon resonance supported by the Si/Au nanocavity. More interestingly, it is demonstrated that the enhancement factor can be manipulated by shifting the exciton/trion resonance close to or far away from the plasmon resonance by simply increasing the laser power. It is revealed that the manipulation is realized by effectively controlling the strain and Purcell effects induced by the Si/Au nanocavity. A PL enhancement factor as large as approximate to 187 in the MoS2/WS2 HB at a high laser power is observed. The findings suggest the potential applications of dielectric-metal hybrid nanocavities in the manipulation of the exciton dynamics in TMDC HBs and the development of novel plasmonic devices.

Automated summary

This study demonstrates the manipulation of exciton dynamics in a heterobilayer by using a Si/Au hybrid nanocavity. The modification of photoluminescence in the embedded heterobilayer is achieved by adjusting the diameter of the Si nanoparticle, which alters the plasmon resonance supported by the nanocavity. The manipulation can be further controlled by shifting the exciton/trion resonance close to or far away from the plasmon resonance through increasing the laser power. The findings highlight the potential applications of dielectric-metal hybrid nanocavities in controlling exciton dynamics and developing new plasmonic devices.