Theoretical Research Of Doped Boron Nitride Nanoribbon Electronic Properties

Boron nitride nanoribbons attracted the attention of scientists after the discovery of graphene,because the hexagonal boron nitride has a similar structure.Despite the similarity,BN nanomaterials have quite different chemical and physical properties.Unlike conductor graphene,BNNR are semiconductors with a wide band gap,high thermal stability,mechanical strength and so on.The geometry structure of the boron nitride nanoribbons could be the key point to creating an alternative material that will complement graphene nanoribbons,but due to the wide band gap this material is difficult to use in pure form.In present days,methods of controlling the band gap and the electronic and magnetic properties of BNNR by the width changing,chirality,edge decoration,as well as the introduction of vacancy and doping defects,are studied.In this paper the influence of carbon doping on the parameters of single layer and bilayer boron nitride nanoribbon is investigated using the density functional theory based on first principles.Calculations showed that carbon doping reduces the band gap and increases the conductivity of all investigated types of ribbons.As the result of the band structure and density of states diagrams analysis the edge effect was discovered in all structures,i.e.,the edge substitution causes a larger number of impurity states in the band structure diagram,compared with the central substitution,and for nanoribbon bilayer the number of impurity states is more than that of a single layer.In addition,these states are closer to the middle of the band gap,while for the central substitution impurity states are located closer to the borders of the band gap.This phenomenon leads to a further increase in conductivity and decrease of the gap width.Nitrogen atoms substitution turned the BNNR into a p-type semiconductor,while the BNNR with boron atom substitution became an n-type semiconductor.Nanoribbon bilayers have a smaller band gap than single layer.In addition,all the doped structures are spin polarized and are magnetic,while all the pure nanoribbons are non-magnetic semiconductors.Thus,carbon doping can increase the conductivity of boron nitride nanoribbons,especially for bilayers,which is desired effect and extends the use of this material in nanoelectronics.