Modulation of optical absorption properties of monolayer InSe by introducing intermediate impurity levels in the band gap

Abstract

The geometry, formation energy, charge density difference, electronic property, work function and optical absorption capacity of transition metals (TM) doped monolayer InSe have been systematically study by first-principles study. TM atoms tend to substitute In atoms under Se-rich growth conditions. Meanwhile, impurity levels (ILs) appear in the band gaps of all TM doped InSe. Especially Mn doping causes the ILs to be located in the middle of the band gap, thus Mn doped monolayer InSe exhibit remarkable optical absorption in the energy range 1.24 ∼ 24.8 eV, which is related to the mechanism of ILs assisted electronic transitions.