First-principles Calculations On Electronic Structures And Optical Properties Of Monolayer MoS₂ And Nonmetallic Element Substituted MoS₂ Monolayer

Monolayer molybdenum disulfide (MoS2) is a prototypical two-dimensional layered material of analogous graphene transition-metal chalcogenides. For its favorable properties in electronics, optics, thermodynamics, chemistry and other aspects of nature, MoS2 has a promising future in application on the secondary graphene bright prospect. Compared with pristine grapheme, the more importantly is that the monolayer MoS2 has a direct band gap of appropriate size. MoS2 has better performance in the application of field-effect diodes and optoelectronic devices. In this paper we calculated the band structure and optical properties of monolayer MoS2 and Oxygen, Fluorine, Chlorine non-metallic atoms substitutional doping monolayer MoS2.1.We perform the calculation on the imaginary part and the real part of dielectric function of the monolayer MoS2 on the basis of the band structure calculation, we has analyzed the corresponding relationship of the interband transitions and the peaks in the dielectric function. Then we have found the conclusion we got is in consistent with previous articles.2.By comparing with monolayer MoS2, we further analyzed what the effect it is to the band structure when monolayer MoS2 is doped by non-metallic atoms. The non-metallic atoms like Oxygen, Fluorine and Chlorine doping MoS2 would change the covalent bond lengths and bond angles neighboring of the dope atom, while the band structure of monolayer MoS2 is extremely sensitive to the changes of lattice constant. We’ve found that the band structure of monolayer MoS2 turn from direct band gap to indirect band gap one. Meanwhile, the Fluorine and Chlorine atoms doping are both kind of donor-type doped, impurity energy levels emerges in the areas that band gap closed to the conduction band.3.Discussion of the optical properties which is influenced by non-metallic atom doped MoS2 is provided in this paper. Oxygen atom doping MoS2 leads to blue shift in the optical absorption. Impurity energy levels emerges in the band structure when Fluorine and Chlorine atom are respectively doping, so the light absorption appears in low energy region.4.Finally, we’ve provided analysis and demonstration of the optical constant of the reflectivity, the refractive index and the extinction coefficient of monolayer MoS2 as well as non-metallic atoms doping monolayer MoS2 system.