First-principles Study Of Anisotropy Of Screening Properties For Black Phosphorus

Black Phosphorus(BP)is a typical layered van der Waals(vd W)material.Its high carrier,tunable band gap and in-band anisotropy attracted people’s attentions.Most properties of BP including electron mobility,optical absorption,thermal conductivity and plasmonic dispersion shows anisotropy due to its unique low-symmety pukered structure.BP’s anisotropic properties have great potential in fileds of BP-based plasmonic devices to high performance thin-film electronics,as well as mid-and nearinfrared optoelectronics.Nevertheless,whether BP show anisotropic is in dispute.Therefore,it is neccesary to discuss the anisotropic screening property of BP.The main topics of this thesis are listed below:1.We study the screening property of BP and the influence of doping based on first-principles calculations.Calculation shows that single-layer/bulk BP shows intrinsic slight anisotropy.Electron and hole doping can both increase the screening of BP and change the relative strength of static dielectric tensors.Besides,with the increasing of doping dgree,anisotropic screening may change to isotropic one.The image of charge density difference also prove that electron/hole doping can tip the balance of anisotropy and isotropy for BP’s screening property.2.We further calculated the influence of doping on dielectric properties of bp-N,which is a high-pressure nitrogen allotrogen with the black phosphorus structure.Different from BP,bp-N exhibits intrinsic obvious anisotropy.Under different doping concentrates,dielectric screening of bp-N increased.In this process,relative static dielectric tensors of bp-N changed.It shows that doping can affect the dielectric properties of bp-N.