Edge Reconstruction And Electronic Properties Of Graphene-like Structure Composed With Group 15 Elements

The successful preparation of graphene opened the door to the research of two-dimensional materials.Since then,new materials have been introduced,such as h-BN,Mo S₂,silicene,germanene,etc.Graphene-like two dimensional（2D）monolayers composed ofβ-structured Group 15（β-G15）elements have attracted great interests due to their intrinsic bandgaps,thermodynamic stabilities,and high mobilities.Quite different from graphene,a buckling amplitude ranging from 1.24?to 1.65?exists along the z direction inβ-G15 films.To learn the influence of this buckling growth behavior on the material properties,this paper presents detailed calculations of various edges composed ofβ-phase VA elements through theoretical simulations,leading to the following conclusions:1.By comparing the edge stabilities ofβ-G15 films,it is found that for the freestandingβ-phase P,As,and Sb films,the zigzag edge with dangling atoms,ZZ（a）,is the most stable one.Forβ-phase Bi films,the pristine AC edge becomes the most stable.When the edges ofβ-G15 films are terminated by hydrogen atoms,the pristine ZZ edge is the most stable,and both of them will grow into hexagonal flakes at equilibrium conditions.In addition,the discussion on the factors affecting edge stabilities and edge growth mechanism provides useful information for guiding the synthesis ofβ-G15films.2.By comparing the edge stabilities of H,F,Cl and S-terminatedβ-G15nanoribbons,it is found that the pristine ZZ or AC edges is the most stable,especially theβ-G15 nanoribbon edges passivated by F and Cl are more stable energetically than that of bare edge,H-terminated and S-terminated nanoribbon edges,indicating that the F₂or Cl₂environment is favorable for the growth ofβ-G15 nanoribbons.Furthermore,the comparison of the edge stresses ofβ-P NRs passivated by bare edges and nonmetallic atoms indicates that H atom passivation favors mechanical stabilities ofβ-P NRs,while Cl atom passivation does not favor mechanical stabilities ofβ-P NRs.The band gap analysis of different edges ofβ-P NRs passivated by nonmetallic atoms shows that edge passivation favors the application ofβ-G15 nanoribbons in electronic and optoelectronic devices.3.By comparing the adsorption positions of Ag atoms on ZZ and AC edges of theβ-P orβ-As nanoribbons,it is found that theβ-P orβ-As nanoribbon edges with one metal atom adsorbed at each ZZ or AC position are the most stable.In addition,by comparing the Zn/.../Ru-terminatedβ-P andβ-As NRs,it is found that the Zn,Cd,Hg-terminated ZZ or AC edges are the most stable.The changes in the magnetic and electronic properties of nanoribbons whenβ-P andβ-As NRs are passivated unilaterally and bilaterally by metal atoms indicate that the decrease of edge unsaturated electrons will reduce the nanoribbon magnetism.Unilateral passivation of metal atoms can be used to control the magnetism ofβ-P orβ-As nanoribbons,in which Fe and Co atoms have the strongest magnetism when unilaterally passivating ZZ or AC edges.When metal atoms passivateβ-P orβ-As NRs bilaterally,most of the metal-terminated nanoribbons magnetism is disappears,but the electronic properties change from semiconductor to metal.This opens up the possibility for the application ofβ-G15nanoribbons in nanodevices and spintronics.