Thermal conductivity of boron nitride nanoribbons: Anisotropic effects and boundary scattering

Previous studies on the thermal conductivity of single-layer boron nitride nanoribbons (BNNRs) are focused on ribbons along the zigzag (ZZ) and the armchair (AC) directions. In this study, we model the thermal conductivity of BNNRs in various transport directions by means of the non-equilibrium molecular dynamics (NEMD) simulations and the Boltzmann transport equation (BTE) under the relaxation time approximation (RTA). In particular, the values of the edge specularity for the boundary scattering, which is closely related to the edge roughness, are obtained at different chiral angles, thereby estimating the anisotropic effects of boundary scattering. It is found that the thermal conductivity has a local maximum at the chiral angle of 19.11°, at which the edge specularity also attains a local maximum. The thermal conductivity generally increases with increasing the ribbon length, yet its value is saturated at a certain length, which significantly depends on the chiral angle. These unusual thermal properties suggest that we may choose optimized structures to achieve better applications of BNNRs in electronic industry.