First-principles study of transition metal elements X(X=Mo,Tc,Ru)doped monolayer GaS
As a member of the two-dimensional(2D)material family,2D GaS has attracted much attention of researchers in recent years,In this paper,the electronic structure properties,magnetic properties and optical properties of monolayer 2D GaS doped with transition metal elements X(X=Mo,Tc,Ru)were calculated based on the density functional theory.The calculation results show that the monolayer GaS material is a non-magnetic semiconductor with an indirect band gap.When the S element is replaced,both the values of the for-mation energy under Ga-rich and S-rich conditions are positive,indicating that the transition metal elements Mo,Tc and Ru cannot spontaneously enter into the monolayer GaS material.All doped systems decrease the band gap of the monolayer GaS.In all doped systems,impurity energy levels are introduced around the Fermi level and they are mainly contributed by the 4d orbitals of the doped atoms.After doping,the band structures of all systems are asymmetric under spin-up and spin-down conditions,making the Mo-doped system become half-metallic ferromagnetic,the Tc-doped and Ru-doped systems are magnetic semiconductor properties.The total magnetic moments after Mo,Tc and Ru doping are 4 μB,3 μB and 2 μB,respectively.The total mag-netic moments of all doped systems are mainly generated by the local magnetic moments of the doped atoms.Moreover,the static dielectric constant of monolayer GaS is improved after doping with transition metal elements X,the polarization ability is enhanced,the absorption spectrum appears red-shifted,the absorption coefficients in the visible and near-infrared regions become larger,and the utilization rate of visible light is enhanced.
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