First-Principles Study of Electronic Structure and Optical Properties of Monolayer and Three-layer MoS2
In this paper,the electronic structure and optical properties of monolayer and three-layer MoS2 are studied using first-principles calculations.The optical characters such as:dielectric function,optical reflectivity,and electron energy-loss spectrum of MoS2 are observed in the energy region from 0 to 15 eV.To the density of states,the conduction band of three-layers of MoS2 has only the low-ener-gy part.At the equilibrium state,the dielectric constants of monolayer MoS2 in the parallel Ex and Ez di-rections are 6.69 and 3.89,respectively,and that in the three-layer MoS2 is 15.01 and 8.39,respec-tively.The dielectric function curve of monolayer MoS2 has a fine structure than that of three-layer MoS2.The dielectric functions have highly anisotropic in the energy range from 0 to 6 eV but they become isotropic when the energy is larger than 7 eV.In the Ex direction,monolayer and three-layer MoS2 have an absorption peak in the visible region.Monolayer MoS2 is more sensitive to near ultraviolet,while three-layer MoS2 is more sensitive to far ultraviolet.As the number of layers increases,the refractive index increases.Both Monolayer and three-layer MoS2 extinction coefficient curves have higher peaks in the near ultraviolet region than in the far ultraviolet area.It can be seen from the electron energy loss spec-trum that with the increase in the number of layers,the peak position moves more and more to the high frequency area.
NETL
NSTL
万方数据
