▎ 摘　　要

Acoustic phonons are defined as the quantum of crystal lattice vibrational energy. The physics of phonon transport within graphene is potentially important and practical. This study relates to the heat conduction properties of graphene nanoribbons deposited on a silicon carbide substrate. The graphene nanoribbons have dimensions comparable to or smaller than the phonon mean free path. The effect of nanoscale grain dimensions on the thermal conductivity of the graphene nanoribbons was investigated experimentally and theoretically to better understand the applied physics of thermal transport at the nanoscale. The characteristics of ballistic and diffusive heat conduction in the graphene nanoribbons were investigated. The edge-scattering effects arising from the crystallographic disorder of the edges of the graphene nanoribbons were determined in order to reduce phonon scattering and enhance phonon transport. The results indicated that the transport mode of phonons depends upon the length scales of the graphene nanoribbons. As the dimensions of the graphene nanoribbons decrease, there is a transition from the diffusive transport mode to the ballistic transport mode. The method of structural and dimensional design is effective to reduce phonon scattering and enhance phonon transport, thereby allowing the thermal conductivity approaching as closely as possible the theoretical limit.