Graphene and boron nitride nanoribbons with multiple doping: an ab initio study

Abstract

Nanoribbons are strong candidates for use in future nanoelectronics devices due to reduced dimensionality end fascinating properties. Despite their rich properties, they have some limitations such as the wide bandgap and no magnetic order of boron nitride nanoribbons and the absence/small energy gap of graphene nanoribbons. The chemical doping of nanoribbons is an interesting topic since the structural, electronic, magnetic, and quantum transport properties could be significantly altered depending on the species of the dopant, the location of the dopants in the structure and their concentration. Here, we study the chemical doping of armchair and zigzag graphene/boron nitride nanoribbons using density functional theory. We investigate the structural, electronic and magnetic properties of these systems. We find that the armchair edge could reduce its energy by establishing a double bond between the outer carbon atoms. Chemical doping with boron and nitrogen atoms in graphene nanoribbons act as a p-type and n-type dopant, which introduce impurity states close to the valence and conduction bands, increasing/opening the energy gap tuning both the nanoelectronic and the nanomagnetic properties. In boron nitride nanoribbons the controlled chemical doping shows itself an important tool to reduce the wide energy gap and to introduce magnetism in these systems. The zigzag graphene nanoribbons, originally, present an imbalance between spin up and spin down, such as their edges belong to different sublattices. However, the doping, in different sublattices, due to the same type of atom, produces a balance between spin up and spin down, resulting in a null polarization.