Self-consistent dielectric constant determination or monolayer WSe2

Abstract

Frequency-dependent dielectric constant dispersion of monolayer WSe2, epsilon(omega) = epsilon(1)(omega) + i epsilon(2)(omega) , was obtained from simultaneously measured transmittance and reflectance spectra. Optical transitions of the trion as well as A-, B-, and C-excitons am clearly resolved in the epsilon(2) spectrum. A consistent Kramers-Kronig transformation between the epsilon(1) and epsilon(2) spectra support the validity of the applied analysis. It is found that the A- and B-exciton splitting in the case of the double-layer WSe2 can be attributed to the spin-orbit coupling, which is larger than that in the monolayer WSe2. In addition, the temperature-induced evolution of the A-exciton energy and its width are explained by model equations with electron-phonon interactions. © 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement