title: Band-gap engineering via tailored line defects in boron-nitride nanoribbons, sheets, and nanotubes.
abstract: We perform a comprehensive study of the effects of line defects on electronic and magnetic properties of monolayer boron-nitride (BN) sheets, nanoribbons, and single-walled BN nanotubes using first-principles calculations and Born-Oppenheimer quantum molecular dynamic simulation. Although line defects divide the BN sheet (or nanotube) into domains, we show that certain line defects can lead to tailor-made edges on BN sheets (or imperfect nanotube) that can significantly reduce the band gap of the BN sheet or nanotube. In particular, we find that the line-defect-embedded zigzag BN nanoribbons (LD-zBNNRs) with chemically homogeneous edges such as B- or N-terminated edges can be realized by introducing a B(2), N(2), or C(2) pentagon-octagon-pentagon (5-8-5) line defect or through the creation of the antisite line defect. The LD-zBNNRs with only B-terminated edges are predicted to be antiferromagnetic semiconductors at the ground state, whereas the LD-zBNNRs with only N-terminated edges are metallic with degenerated antiferromagnetic and ferromagnetic states. In addition, we find that the hydrogen-passivated LD-zBNNRs as well as line-defect-embedded BN sheets (and nanotubes) are nonmagnetic semiconductors with markedly reduced band gap. The band gap reduction is attributed to the line-defect-induced impurity states. Potential applications of line-defect-embedded BN nanomaterials include nanoelectronic and spintronic devices.
authors.affiliation: CAS Key Laboratory of Materials for Energy Conversion and Department of Material Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
authors.forename: Xiuling
authors.initials: X
authors.lastname: Li
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Wu
authors.forename: Xiao Cheng
authors.initials: XC
authors.lastname: Zeng
authors.forename: Jinlong
authors.initials: J
authors.lastname: Yang