Large-Scale characterization of Two-Dimensional Monolayer MoS₂ Island Domains Using Spectroscopic Ellipsometry and Reflectometry

Motivated by their unique physical and chemical properties, the scientific research on two-dimensional (2D) materials has been intense in the last decade and as a result of these efforts, layered materials are seriously considered for integration into a wide variety of technologies. The great advance in the synthesis of such materials will require fast and accurate characterization methodologies on the large-scale. Here we present the implementation of Spectroscopic Ellipsometry and Reflectometry for the fast characterization of inhomogeneous MoS₂ films grown by chemical vapor deposition on SiO₂/Si substrates. In order to account for the non-uniformities in the films, often encountered in such materials, an “Island-Film model” was utilized. As a result, the average thickness, coverage and optical parameters of the MoS₂ domains could be extracted in a single measurement. The optical dispersion and bandgap results fit well with previously reported values, while the thickness and coverage were corroborated using optical microscopy, Raman and Photoluminescence (PL) spectroscopy and Atomic Force Microscope (AFM). This work presents a significant milestone in applying fast and accurate methodologies for the large-area characterization of 2D materials, as required for the success integration of such layered compounds into novel and existing technologies.