Enhanced photoluminescence of monolayer MoS2 on stepped gold structure

Abstract

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.