Disentangling mass effects from crystal chemistry in the thermal properties of III-V insulators

BAs, a III-V insulator, has a thermal conductivity comparable to diamond and a higher thermal conductivity than other cubic III-V boron compounds. The origin of this high thermal conductivity has been attributed to the mass ratio and unique chemical bonding character of BAs, both of which give rise to specific features in the phonon dispersion curve that determine the available scattering phase space [Phys. Rev. X 10 021063 (2020)]. We use first-principles density functional theory in combination with the Boltzmann transport equation to systematically explore and disentangle the effects of mass ratio and bonding and chemistry on the thermal conductivity of the entire column of cubic III-V boron compounds, from c-BN to BSb. Our preliminary results and previous work [J. Appl. Phys. 116 073503 (2014)] suggest that although the mass ratio of BAs may optimally maximize thermal conductivity, there may be a pathway to further increasing thermal conductivity through modifying bonding and chemistry. Our work provides hints regarding the chemical characteristics of high thermal conductivity materials.