Extended line defects in BN, GaN, and AlN semiconductor materials: Graphene-like structures

Highlights: • Extended line defects (ELD) formed by 8-4 membered rings are energetically stable. • ELD could help to understand the grain boundaries in two dimensional materials. • It was found that the ELD are more stable in GaN and AlN than in BN monolayers. • The band gap is reduced when ELD are introduced into the honeycomb structures. • Nanoribbons and monolayers with ELD exhibited in-gap states. The extended line defect (ELD) mimicking grain boundaries in two-dimensional systems is theoretically investigated in BN, GaN, and AlN semiconductor materials with a single layer honeycomb structure. The ELD consists of octagonal–square membered rings. Density functional calculations of the electronic density of states, scanning tunneling microscopy and transmission electron microscopy image simulations are analyzed. Our results revealed that the ELDs are stable in all considered monolayers. In addition, electronic density of states calculations demonstrated that in gap states are emerged when ELD is incorporated into the honeycomb structures. Finally, results on armchair nanoribbons with bare-edges and hydrogenated edges are discussed.