Stability of and conduction in single-walled Si2BN nanotubes

Abstract

We explore the possibility and potential benefit of rolling a ${\mathrm{Si}}_{2}\mathrm{BN}$ sheet into single-walled nanotubes (NTs). Using density functional theory (DFT), we consider both structural stability and the impact on the nature of chemical bonding and conduction. The structure is similar to carbon NTs and hexagonal boron-nitride (hBN) NTs and we consider both armchair and zigzag ${\mathrm{Si}}_{2}\mathrm{BN}$ configurations with varying diameters. The stability of these ${\mathrm{Si}}_{2}\mathrm{BN}$ NTs is confirmed by first-principles molecular dynamics calculations, by exothermal formation, an absence of imaginary modes in the phonon spectra. Also, we find the nature of conduction varies from semiconducting over semimetallic to metallic, reflecting differences in armchair/zigzag-type structures, curvature effects, and the effect of quantum confinement. We present a detailed characterization of how these properties lead to differences in both the bonding nature and electronic structures.