Electronic Structure And Magnetism Of Vacancy-doped Phosphorene: Effects Of Biaxial Strain

Phosphorene, monolayer structure of black phosphorus, was produced by using micro mechanical stripping and plasma thinning by Wanglin Lu, Haiyan Nan et al. Similar with graphene, phosphorene is another two dimensional nanomaterials consisting of single type of atom. It possesses excellent optical, electronic and magnetic properties. Especially, phosphorene has both high carrier mobility(1000 cm2 V-1 s-1) and direct band gap. Because of the exotic properties, phosphorene has great application in various electronic device applications including P/N junction, solar cells, field effect transistor(FET).In order to use of phosphorene flexibly and effectively, it is of crucial importance to modulate its electronic properties controllably. It’s found that the electronic properties of phosphorene can be tuned by the strain based on its excellent mechanical properties. It is well known that the strain and defects will exist inevitably during the preparation and application, which are also very important for the properties of phosphorene. In this work, we have studied the modulation of the electronic structure and the magnetic properties of phosphorene under biaxial strain(tension / compression) using the first-principles methods.Firstly, the effects of single vacancy(SV956, SV5566) and double vacancies(DVp, DV4104, DVa) on the electronic properties of phosphoene have been studied. It’s found that the defects will induce the defect band in the band gap, which can be modulate by the strain. As biaxial tensile strain increases, the band gap increases firstly and then decreases except for the phosphoene whit SV956 defect, and the defect band moves towards to the valence band. Under increasing compressive biaxial strain, the band gap decreases monotonically. For single vacancy, the defect band is strongly localized and moves to the conduction band. For the double vacancy, the defect bands are distributed on the edge of the conduction band and move into the conduction band as the strain increases.Furthermore, we have studied the of phosphorene with single vacancy(SV956, SV5566) and double vacancies(DVp, DV4104, DVa). The results show that the biaxial strain has important effect on magnetic properties. Without strain, only SV956 vacancy induces magnetism for unstrained phosphorene, owing to dangling bonds caused by the Jahn-Teller distortion around the defect. Biaxial strain modulates the magnetic state for SV956 doped phosphorene and induces nonzero magnetic moment for SV5566 and DVa doped phosphorene, as the biaxial strain influences the local bonding configuration and then the magnetic moment. Our work promises an effective route towards the operation of phosphorene-based low-dimensional spintronics by strain.