Size effect of thermal conductivity in monolayer graphene

We use the none quilibrium molecular dynamics method to investigate the thermal conductivity of both suspended and supported graphene at room temperature. Significant size (both length and wide) effect is observed in thermal conductivity of suspended monolayer graphene. And it is found that the thermal conductivity value would converge to a constant value as further increasing size. In the case of supported graphene, we find the thermal conductivity is much lower than that of its suspended counterpart, and the suppressed size effect on thermal transport is obtained. The underlying physics of the size effect on both suspended and supported graphene is investigated and presented in terms of phonon transport analysis. These results show the nature of phonon transport in graphene and provide a useful guide for tailoring and engineering of the thermophysical properties of graphene in thermo-electronic and photonic devices.