Thermal transport in graphene supported on copper

Abstract

We investigate the thermal transport in isolated single layer graphene (SLG) and SLG supported on Cu substrate using equilibrium molecular dynamics simulations and relaxation time approximation (RTA) method. We observe significant changes in the SLG dispersion curve in low frequency and low wave-vector region due to the interaction with Cu substrate. Several new phonon modes related to out-of-plane vibrations appear at the low frequency and small wave vector regions, but their contribution to graphene thermal conductivity is negligible. The thermal conductivity of graphene decreases by 44% due to the interactions with Cu substrate for high interaction strength parameter in Lennard-Jones potential formulation for graphene-Cu interaction. The phonon mode analysis through the RTA approach shows that the acoustic phonons dominate the thermal transport for both isolated and supported graphenes. The longitudinal acoustic (LA), transverse acoustic (TA), and out-of-plane acoustic (ZA) phonons contribute 654, 330, and 361 W/mK to the lattice thermal conductivity of isolated graphene, respectively. The phonon life time of ZA modes decreases by order of magnitude due to the interactions with Cu substrate and ZA mode contribution to SLG thermal conductivity decreases by 282 W/mK, while the contributions of LA and TA phonons reduce by 77.4 W/mK and 82.9 W/mK, respectively.