Electronic band structures of graphene nanoribbons with self-passivating edgereconstructions

Abstract

Using the nearest-neighbor tight-binding approach we study the electronic band structuresof graphene nanoribbons with self-passivating edge reconstructions. For zigzag ribbons theedge reconstruction moves both the Fermi energy and the flat band down by severalhundred meV, and the flat band is always found to be below the Fermi energy. The statesfeatured by the flat band are shown to be mainly localized at the atoms belonging toseveral lattice lines closest to the edges. For armchair ribbons the edge reconstructionstrongly modifies the band structure in the region close to the Fermi energy, leading to theappearance of a band gap even for ribbons which were predicted to be metallic inthe model of standard armchair edges. The gap widths are, however, stronglydifferent in magnitude and behave in different ways regarding the ribbon width.