Thermal conductivity of Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Prepared by Coaxial Arc Plasma Deposition

The thermal conductivity of ultrananocrystalline diamond/hydrogenated amorphous carbon composite films prepared by coaxial arc plasma deposition (CAPD) was measured by a time-domain thermoreflactance method. The specific heat and density of the films were measured to be 0.891 J/g.K and 1.70 g/cm(3), respectively, as parameters for the estimation of the thermal conductivity. Based on them, the thermal conductivity was estimated to be 2.32 W/m.K. This value is smaller than that of general UNCD/a-C: H films prepared by chemical vapor deposition (CVD). It might be because the CAPD films possesses a huge number of grain boundaries owing to extremely small grains of approximately 2.3 nm as compared with those of CVD films and its structure enhances phonon scattering.