Impurity Effects On The Magnetism And Electronic Structures Of Monolayer Tin Selenide

The ?-? semiconductor materials have shown distinctive thermoelectric,photoelectric and magnetism properties.As one of the ?-? semiconductor materials,Tin selenide(SnSe)has been synthesized in the laboratory.The reserves are abundant for two of its constituent elements Sn and Se.And both of the two composed elements Sn and Se are environmentally friendly elements.The direct band gap and indirect band gap of bulk tin selenide are 1.30 e V and 0.90 eV,which fall within the optimum band gap for solar cells.So bulk tin selenide is considered as the most promising candidate for solar cells.As is chemical stability high,the tin selenide semiconductor can be applied in optical devices,memory switching devices,infrared optoelectronic devices and anode materials for rechargeable lithium batteries.The excellent optical properties of tin selenide have been concerned,while the potential magnetic property of tin selenide is neglected.In this paper,combined with supercetl model,pseudo potential and the VASP package,we study the effects of electric field on magnetism of Ti-and Zn-doped monolayer tin selenide and the effects on electronic structure of N-?P-and Cl-doped tin selenide by using the first-principles calculation method.The main results are given as follows:1.The effects of electric field on magnetism of Ti-and Zn-doped monolayer tin selenideThe magnetism of transition metal(TM = Zn,Ti)doped monolayer tin selenide are investigated by using first-principles method based on density functional theory.One of the Sn atoms in tin selenide is substituted.The calculation indicates that the Ti substituted Sn is easier than Zn does in monolayer tin selenide.No magnetism is found in Zn-doped tin selenide,while Ti-doped SnSe displays magnetism and the Fermi level of Ti-doped monolayer tin selenide moves to the bottom of the conduction band.The external electric field makes Ti-and Zn-doping in tin selenide hardly.The external electric field induces the charge redistribution of Ti-doped tin selenide.Furthermore,from-0.4 V/? to 0.4 V/?,the influences of external electric field on the magnetism of Ti-and Zn-doped SnSe are slight.2.The effects on electronic structure of N-,P-and Cl-doped tin selenideThe N-,P-? Cl-doped monolayer tin selenide are investigated by using first-principles method based on density functional theory.One of the Se atoms in tin selenide is substituted.No magnetism is found in N-,P-and Cl-doped monolayer tin selenide systems.The calculation indicates that the N substituted Se is easier than P and Cl do in monolayer tin selenide system.The Fermi level of N-and Pdoped monolayer selenide systems move into the valence band.The Fermi level shift deeper into the valence band for P-doped than N-doped monolayer tin selenide system.The Fermi level of Cl-doped monolayer tin selenide system moves to the bottom of the conduction band.