Phonon transport simulations in low-dimensional, disordered graphene nanoribbons

In this work we investigate phonon transport in low-dimensional, disordered armchair graphene nanoribbons (GNRs). We use the non-equilibrium Green´s function (NEGF) simulation technique and the force constant method. We focus on how different parts of the phonon spectrum are influenced by geometrical confinement and line edge roughness. In the ballistic case, phonons throughout the entire phonon energy spectrum contribute to thermal transport. With the introduction of line edge roughness, the phonon transmission is reduced, but quantitatively and qualitatively in different ways throughout the energy spectrum. We identify how each region of the spectrum reacts to low-dimensionality and disorder, and elaborate on how phonon transport is affected by that. We explain how and when phonons in different energies within the spectrum flow either ballistically, diffusively, or become localized depending on the channel geometry.