High thermal conductivity in covalently bonded bi-layer honeycomb boron arsenide

Abstract

Semiconducting materials with high thermal conductivity are valuable for thermal management in highly integrated systems, in which heat must be dissipated efficiently. Cubic boron arsenide (BAs) is recently attracting numerous research attention due to its comparable thermal conductivity with diamond. However, thermal conductivity of monolayer honeycomb BAs is much lower than the bulk counterpart. Herein, based on Boltzmann transport equation and non-equilibrium Green’s function calculation, we suggest a new unexplored covalently bonded bi-layer BAs to exhibit high thermal conductivity, which is about two times of that of bulk silicon. Unlike the remarkable reduction in thermal conductivity from monolayer graphene to bi-layer graphene, thermal conductivity of bi-layer BAs is about 70% higher than its monolayer counterpart. Central to this novel behavior was the largely suppressed phonon scattering phase space and anharmonicity. The anomalously high thermal conductivity of the covalently bonded bi-layer BAs and the emergent underlying mechanism discussed here open up space for further manipulation of thermal properties of 2D materials, and facilitate their applications to important problems in nanoscale electronic and optoelectronic devices.