Spatial Modulation of Vibrational and Luminescence Properties of Monolayer MoS2 Using a GaAs Nanowire Array

The integration of transition-metal dichalcogenides (TMDs) with non-planar substrates such as nanopillars provides a way to spatially modify the optical properties mainly through the localized strain. Similar studies to date have utilized insulating SiO2 nanopillars. Here, we combine monolayer MoS2 with free standing GaAs nanowires (NWs), in views of coupling their semiconducting properties. We find that monolayer MoS2 exhibits three different configurations: pierced, wrapped and tent-like. We demonstrate how to identify the configurations by optical microscopy and elucidate the impact on the vibrational and luminescence characteristics by confocal spectroscopy mapping. In particular, we highlight the increase of intensity and shift due to the photonic properties of nanowires and increase in dielectric screening associated with the GaAs NW. This work signifies the first step towards the use of vertical III-V NW arrays as a versatile platform for spatially engineering the optical properties of TMDs.