Thermal conductivity of group-III phosphides: The special case of GaP

Abstract

We calculate the lattice thermal conductivity of cubic group-III phosphides by solving the linearized Boltzmann transport equation for phonons and discuss how there is a large disagreement between the literature values for GaP. We find the presence of comparably large third-order interatomic force constants at large interaction distances that influence the thermal conductivity of GaP. When both four-phonon scattering and the contributions from the long-range interactions are included in the calculation, a thermal conductivity of $76\phantom{\rule{0.28em}{0ex}}{\mathrm{W}\phantom{\rule{0.16em}{0ex}}\mathrm{m}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ is obtained at room temperature, in good agreement with a reported experimental value of $77\phantom{\rule{0.28em}{0ex}}{\mathrm{W}\phantom{\rule{0.16em}{0ex}}\mathrm{m}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$. Our results show the importance of carrying out convergence tests with respect to all the calculation parameters and could help explain the thermal conductivity in other systems where similar ambiguities are found.