Modulating the electronic, magnetic and optical properties of 1T-SnSe_2 monolayer by defects: An ab initio study

摘要

We investigate the effect of vacancies and doping on the electronic, magnetic and optical properties of lT-SnSe_2 monolayer by using density functional theory calculations. The results reveal that the semiconducting lT-SnSe_2 monolayer becomes a half-metal on creating one tin vacancy (V_(1Sn)), while it is still a semiconducting on creating one selenium vacancy (V_(1Se)), two selenium vacancy (V_(2Se)), as well as one tin and one selenium vacancy (V_(1Sn+1Se))- The V_(1Sn) and V_(1Sn+1Se) vacancies induce magnetic ground states with net magnetic moments of 4 and 2 μ_B respectively, while the V_(1Se) and V_(2Se) vacancies induce nonmagnetic ground states. In Mo-doped lT-SnSe_2 monolayer, crystal-field splitting of Mo-4d orbital in the octahedral environment induces net magnetic moment of 2 μ_B- The band structure and density of states also show that the Mo-doped system is a magnetic semiconductor. In addition, the defective lT-SnSe_2 mononlayer can also enhanced the absorption efficiency of the solar energy, particularly in the infrared region. An interesting red-shift phenomenon has been observed in the curves of imaginary part of the dielectric function and absorption spectra for the defect systems, suggesting their quite promising applications in optoelectronic devices.