The electronic and optical properties of the monolayer Mo(SxSe1-x)2 by the first-principle calculations

Abstract

First-principles calculations are conducted to explore the electronic and optical properties of the monolayer Mo(S_xSe_1-x)₂. It is found that the monolayer Mo(S_xSe_1-x)₂ possesses a direct bandgap. Through fitting the theoretical and experimental data, the bandgap bowing parameter of 0.051 eV is attained. The enlargement of the bandgap energy is by reason of the decline of the K VBM. In the full component range, the downward movements of the K CBM and the K VBM are dominated by the $p_{S-3p}-d_{\mathrm{Mo}-4d}$ coupling interaction and the total p-d coupling interaction, respectively. For the optical properties, it is found that increasing S component can reduce the static dielectric constant. However, the B and C excitons as well as E₃ shift toward the higher energy direction with increasing S component. It is also found that increasing S component has a small effect on enhancing the light absorption. The photoconductivity shows a similar result with the absorptivity.