Characterization of 2D Transition Metal Dichalcogenides Through Anisotropic Exciton Behaviors

This study reports the first attempt to characterize the quality, defects, and strain of as-grown monolayer transition metal dichalcogenide (TMDC)-based 2D materials through exciton anisotropy. A standard ellipsometric parameter (psi) to observe anisotropic exciton behavior in monolayer 2D materials is used. According to the strong exciton effect from phonon-electron coupling processes, the change in the exciton in the Van Hove singularity is sensitive to lattice distortions such as defects and strain. In comparison with Raman spectroscopy, the variations in exciton anisotropy in psi are more sensitive for detecting slight changes in the quality and strain of monolayer TMDC films. Moreover, the optical power requirement for TMDC characterization through exciton anisotropy in psi is approximate to 10-5 mW cm-2, which is significantly less than that of Raman spectroscopy (approximate to 106 mW cm-2). The standard deviation of the signals varies with strain (defects) in Raman spectra and exciton anisotropies in psi are 0.700 (0.795) and 0.033 (0.073), indicating that exciton anisotropy is more sensitive to slight changes in the quality of monolayer TMDC films. This study reports the first attempt to characterize the as-grown quality, defects, and strain of transition metal dichalcogenide (TMDC)-based 2D materials through exciton anisotropy. A simple ellipsometric parameter-based method for observing the anisotropic excitonic behavior in 2D monolayer materials is demonstrated. The change in the exciton of TMDCs in the Van Hove singularity is superior to the detection indicator.image

Automated summary

This study is the first attempt to characterize the quality, defects, and strain of as-grown monolayer transition metal dichalcogenide (TMDC)-based 2D materials through exciton anisotropy. The use of a simple ellipsometric parameter allows for more sensitive detection of slight changes in the quality and strain of monolayer TMDC films.