Phonon transmission and thermal conductance across graphene/Cu interface

We investigate phonon transmission and thermal boundary conductance (TBC) across graphene/Cu interface using density functional theory and atomistic Green's function method. The analysis of phonon dispersions and density of states of single layer graphene (SLG) shows that even weak SLG/Cu interaction can soften the transverse optical and longitudinal optical modes and suppress low frequency out-of-plane acoustic (ZA) modes. Our calculations predict that a small stretching of the SLG lattice (∼1.6%) significantly enhances the SLG/Cu interaction which is reflected in larger band-gap for ZA/ZO phonon mode and a remarkable increase in TBC (∼59%).