Enhanced photoluminescence of monolayer MoS2 on stepped gold structure

Different MoS₂/Au heterostructures can play an important role in tuning the photoluminescence (PL) and optoelectrical properties of monolayer MoS₂. Previous studies of PL of MoS₂/Au heterostructures were mainly limited to the PL enhancement by using different Au nanostructures and PL quenching of monolayer MoS₂ on flat Au surfaces. Here, we demonstrate the enhanced excitonic PL emissions of monolayer MoS₂/Au heterostructures on Si/SiO₂ substrates. By transferring the continuous monolayer MoS₂ onto a stepped Au structure consisting of 60-nm and 100-nm Au films, the MoS₂/Au-60 and MoS₂/Au-100 heterostructures exhibit enhanced PL emissions, each with a blue-shifted PL peak in comparison with the MoS₂/SiO₂. Furthermore, the PL intensity of MoS₂/Au-60 is about twice larger than that of MoS₂/Au-100. The different enhanced excitonic PL emissions in MoS₂/Au heterostructures can be attributed to the different charge transfer effects modified by the stepped Au structure. This work may provide an insight into the excitonic PL and charge transfer effect of MoS₂ on Au film and yield novel phenomena in MoS₂/Au heterostructures for further study of PL tuning and optoelectrical properties.