Temperature dependent thermal conductivity of a suspended submicron graphene ribbon

Thermophysical characterization of graphene is very important for both fundamental and technological research. While most of the existing thermal conductivity measurements are for graphene sheets with sizes larger than 1 μm, the thermal conductivities for suspended submicron graphene ribbons are still very few, although the thermal conductivity of graphene ribbons at the submicron scale is predicted to be much smaller than large graphene and strongly size dependent for both length and width due to the 2D nature of phonon transport. Here, we report the temperature dependent thermal conductivity of a 169-nm wide and 846-nm long graphene ribbon measured by the electrical self-heating method. The measured thermal conductivities range from (12.7 ± 2.95) W/m/K at 80 K to (932 ± 333) W/m/K at 380 K, being (349 ± 63) W/m/K at 300 K, following a ∼ T^2.79 law for the full temperature range of 80 K to 380 K and a ∼ T^1.23 law at low temperatures. The comparison of the measured thermal conductance with the ballistic transport limit indicates diffusive transport in this narrow and short ribbon due to phonon-edge as well as phonon-defect scattering. The data were also combined with an empirical model to predict possible width dependence of thermal conductivity for suspended graphene ribbons. These results help understand the 2D phonon transport in suspended submicron graphene ribbons and provide knowledge for controlling thermophysical properties of suspended graphene nanoribbons through size manipulation.