Investigation of the optical properties of MoS2 thin films using spectroscopic ellipsometry

Abstract

Spectroscopic ellipsometry (SE) characterization of layered transition metal dichalcogenide (TMD) thin films grown by vapor phase sulfurization is reported. By developing an optical dispersion model, the extinction coefficient and refractive index, as well as the thickness of molybdenum disulfide (MoS2) films, were extracted. In addition, the optical band gap was obtained from SE and showed a clear dependence on the MoS2 film thickness, with thinner films having a larger band gap energy. These results are consistent with theory and observations made on MoS2 flakes prepared by exfoliation, showing the viability of vapor phase derived TMDs for optical applications.