First-principles Study On Doped Monolayer Black Phosphorus And Hexagonal Boron Phosphide

In recent years,with the rapid development of nanotechnology,two-dimensional semiconductor materials are widely used in electronic devices and other fields.The bandgap,magnetism,carrier mobility and other properties of semiconductor materials directly affect thier application in the field of electronic devices.The two-dimensional material,such as monolayer black phosphorus,has showed a promising application prospect for the preparation of novel electronic nanometer devices because of its suitable bandgap,high carrier mobility and anisotropic property.Materials often need to be modified to expand application and optimize their performance.Doping can effectively control the electronic structures and magnetic properties of two-dimensional materials,thus providing thereitical bases for their application in spin electronics.Therefore,based on the first principle calculation,we study the effects of atomic doping on the electronic properties and magnetic properties of monolayer black phosphorus,which provides an indispensable theoretical basis for experimental investigation.In this paper,based on the first-principles method of density functional theory,we use the VASP software package to study single-layer black phosphorus doped with different concentrations of Si,S and B.The PBE method based on generalized gradient approximation is used to correct the electron-electron interaction associated with the exchange of energy correction.We discuss the effects of different concentrations of Si,S,B,especially 50% B doping on the structural stabilities,band structures,partial density of states and electrical properties for monolayer black phosphorus.The results as follows:Firstly,the geometric structures of monolayer black phosphorus have been changed by the doping of Si,S and B atom.Among them,the deformation of Si-doped system is the smallest,and the deformation of B-doped system is the largest.The bandgaps and magnetic properties of the systems are also changed after doping.The bandgaps varies from 0.26 eV to 0.93 eV.The intrinsic monolayer black phosphorus shows no magnetism,and the B-doped system also shows no magnetism.For the S-doped system,the total magnetic moment of the S-doped system decreases from 1 ?B to 0 ?B with the increase of S doping concentration.Secondly,the higher doping concentration of B atom,the greater the concave deformation of B atom.When 50% concentration of B atoms dope monolayer black phosphorus by mixed doping,the system transforms from the pleated construction into planar hexatomic ring structure,thus forming a novel hexagonal boron phosphide(h-BP)structure.For the last one,the novel monolayer h-BP compound has not been synthesized experimentally,but its stability has been studied in some theoretical calculations.We further study the thermal stability,electronic property and mechanical property of single layer h-BP,and compare it with common two-dimensional materials,such as monolayer graphene,monolayer hexagonal boron nitride and monolayer black phosphorus.We also explain the reason for the different conductivity of graphene,hexagonal boron nitride and h-BP based on the charge density.By calculation,we found that the novel h-BP compound has suitable direct bandgap,large carrier mobility,structural stability,high temperature resistance and excellent chemical stability,etc.So it is an ideal two-dimensional semiconductor material,which has a wide application prospect in the field of semiconductor devices.In short,atomic doping can change the geometrical structures,electronic properties and magnetic properties of monolayer black phosphorus,while material changes greatly different with different doping atoms and doping concentrations.When the B atom is doped at a high concentration of 50%,the electronic property of the system has changed greatly,which forms a novel h-BP compound.By studying the stability,electronic property and mechanical property of novel h-BP compound,we found that the material has excellent properties which are not available in other known two-dimensional materials,so it has great potential on the application of semiconductor electronic devices.