Abstract

In this presentation, analysis of 2D nanomaterials with Tip enhanced Raman scattering (TERS) will be provided. TERS is a unique tool for investigating Raman scattering mapping with nanometer spatial resolution beyond optical diffraction limit. Using representative tips fabricated under the optimal etching condition, Our lab. demonstrate the TERS experiment of tungsten disulfide (WS₂) monolayer grown by a chemical vapor deposition method with a spatial resolution of ~40 nm. Monolayer WS₂ has emerged as an active material for optoelectronic devices due to its quantum yield of photoluminescence. Despite the enormous research about physical characteristics of monolayer WS₂, the defect-related Raman scattering has been rarely studied. In this work, we report the correlation of topography and Raman scattering in monolayer WS₂ by using TERS and reveal defect-related Raman modes denoted as D and D′ modes. We found that the sulfur vacancies introduce not only the red-shifted A1g mode but also the D and D′ modes by the density functional theory calculations. The observed defect-related Raman modes can be utilized to evaluate the quality of monolayer WS₂ and will be helpful to improve the performance of WS₂ optoelectronic devices.

© 2019 Japan Society of Applied Physics, The Optical Society (OSA)