First-principles Studies On The Magnetic And Optical Properties Of SnS₂ And SiC By Doping

Two-dimensional tin disulfide（SnS₂）has the advantages of good chemical stability,non-toxicity,low cost,high content,and good electrical,optical,and magnetic properties.Therefore,SnS₂is generally used in field effect transistors,photodetectors and photocatalysts.Due to its excellent properties,SnS₂has been extensively studied both theoretically and experimentally.And silicon carbide（SiC）is a semiconductor material with excellent physical properties,such as wide band gap,high critical breakdown field strength,and high thermal conductivity.In this paper,based on density functional（DFT）theory,SnS₂system and SiC system are studied,and the results are as follows:（1）The SnS₂structure was constructed,and the magnetic and optical properties of the doped system were calculated by first-principles simulation.The results show that both Fe atom doped SnS₂and Cr atom doped SnS₂have magnetic properties.In the（Fe,Cr）co-doped SnS₂system,Fe atoms,Cr atoms and adjacent S atoms form strong hybridization.Namely,the nearest S atom between Fe and Cr atoms mediates spin polarization and ferromagnetic coupling.Furthermore,with the introduction of Fe and Cr atoms,the absorption coefficients are maximized in the long-wavelength infrared region of 0.23～1.63 e V.The doping of Fe and Cr can make up for the insufficient absorption of intrinsic materials in the infrared region.（2）The SnS₂structure was constructed,and the magnetic and optical properties of the doped system were calculated by first-principles simulation.It is found that the doped systems are all magnetic.The introduction of dopant atoms enhances the electromagnetic absorption capability of the dielectric function and increases the electrical conductivity.Mn doped SnS₂and（Fe,Mn）co-doped SnS₂have low transmittance properties in the visible and ultraviolet range.The Fe doped and(Fe,Mn,V_Sn)co-doped SnS₂exhibits high transmittance properties in the visible and ultraviolet range.（3）The magnetic and optical properties of（In,Mn）co-doped 4H-SiC and（In,2Mn）co-doped 4H-SiC systems are calculated.It is found that the local magnetic moment of the（In,Mn）co-doped 4H-SiC system is 5.14.And（In,2Mn）co-doped 4H-SiC system can obtain the most stable ferromagnetic state.In addition,the introduction of dopant atoms can reduce the band gap and improve the conductivity.The doping system can weaken the maximum dielectric peak,thereby weakening the electromagnetic absorption ability in 4H-SiC.The doped system shows a red shift.And the transmittance of the doped system in the infrared and visible regions is low.（4）The 3C-SiC structure was constructed,and the magnetic and optical properties of the doped system were calculated by first-principles simulation.The calculation results show that the intrinsic 3C-SiC is a non-magnetic semiconductor.Fe atom,Co atom singly doped 3C-SiC and（Fe,Co）co-doped 3C-SiC have spin polarization and magnetism.From the imaginary part of the dielectric function and the absorption spectrum,it is found that the single-doped and co-doped systems have red-shifted absorption edges,and the optical band gap is reduced.