First-Principles Study Of D₂ Family Doped Molybdenum Disulfide Thin Films

In recent years,MoS2 thin films have attracted much attention due to their potential applications in the fields of electricity,optics,lubrication and catalysis.In order to improve the performance of MoS2 film,the most commonly used methods are doping,applied stress(including external stress and defect stress),electric field and adsorption,these methods can change the electronic structure of MoS2.It has been reported in the literature that doping can significantly change the electronic structure and properties of MoS2 thin films.This paper makes a study on d2 doped MoS2 films.In this paper,the first principles study of the intrinsic and d2 doped MoS2 thin films was carried out.Using DFT theory and application of MS software,established models of intrinsic and d2 doped MoS2 films,the convergence test of calculation parameters,combined with the test parameters were optimized on structure model.On this.basis,the electronic structure,optical properties and elastic constants of intrinsic and doped MoS2 films were calculated and analyzed.The intrinsic and doped films were prepared by electrodeposition method,and the corresponding optical properties were characterized and compared with the results of the first principle.The calculated results show that the intrinsic MoS2 films are direct band gap semiconductors,while the doped MoS2 films are indirect band gap semiconductors,and the band gap decreases from 1.876eV to 0.165eV,0.131eV and 0.129eV,respectively.Simultaneous doping makes the MoS2 material appear new doping level.The optical properties of the MoS2 films show that the absorption peaks of the new UV spectra are obtained by doping,and the optical frequency range of the visible and infrared regions is increased.With the doping of Ti,Zr and Hf,the peak value of UV absorption gradually becomes larger,and the range of the light frequency in the visible and infrared region of the MoS2 thin film is larger.The experimental results show that the surface morphology of Ti thin films becomes more uniform and the particles become smaller.The results show that the density of states explains that the π-bond formed by Mo-4d and S-3p is weakened by the introduction of dopant elements,which reduces the movement of the conduction band and the valence band to the high energy region.After the band gap becomes smaller.With the difference charge density,the doped atoms and the sulfur atoms can form stronger chemical bonds,and the charge sharing increases.And the optical properties of MoS2 thin films were changed.The strong absorption peak of MoS2 thin film in the blue violet region was analyzed by the absorption coefficient spectrum,which explained the reason why the MoS2 film was blue and purple.The experimental results show that the absorption peaks appear in the UV region after doping,and the absorption peak of the visible light decreases,which is in agreement with the results obtained from the first principles study.