Effects of inherent phonon scattering mechanisms on the lattice thermal conductivity of graphene

The phonon transport properties of graphene with different crystal scales were studied theoretically with full dispersion relations in order to understand the inherent phonon scattering mechanisms responsible for the decrease in the thermal conductivity of graphene. The effects of inherent phonon scattering mechanisms were evaluated at different temperatures. The roles of various inherent phonon scattering parameters were determined, including polarization, anharmonicity, specularity, chirality, and microscopic density fluctuations. Each phonon branch contribution was determined. The results indicated that anharmonicity, specularity, and microscopic density fluctuations are of great importance. Chirality is intimately associated with the phonon transport properties of graphene. When making predictions, the Gruneisen parameter dependence on polarization branches is of critical importance to determine the thermal conductivity, and the phonon scattering caused by isotopes must be included explicitly. Phonon anharmonicity is essential for explaining thermal transport phenomena, and the Gruneisen anharmonicity parameter can provide valuable insights into how the thermal conductivity couples to phonon modes or vibrational frequencies. When the mass-fluctuation-scattering parameter increases from 0 to 0.1, the thermal conductivity is decreased by half. The isotope scattering effect is considerable, and polarization greatly affects the relative phonon branch contribution, especially at lower temperatures. Studies of these effects contribute to an understanding of the roles of various inherent phonon scattering parameters.