Excitonic absorption and defect-related emission in three-dimensional MoS2 pyramids

Abstract

MoS₂ micro-pyramids have demonstrated interesting properties in the fields of photonics and non-linear optics. In this work, we show the excitonic absorption and cathodoluminescence (CL) emission of MoS₂ micro-pyramids grown by chemical vapor deposition (CVD) on SiO₂ substrates. The excitonic absorption was obtained at room and cryogenic temperatures by taking advantage of the cathodoluminescence emission of the SiO₂ substrate. We detected the CL emission related to defect intra-gap states, localized at the pyramid edges and with an enhanced intensity at the pyramid basal vertices. The photoluminescence and absorption analysis provided the Stokes shift of both the A and B excitons in the MoS₂ pyramids. This analysis provides new insights into the optical functionality of MoS₂ pyramids. This method can be applied to other 3D structures within the 2D materials family.