Thermal conductivity of diamond-like carbon films

The authors report the thermal conductivity (K) of a variety of carbon films ranging from polymeric hydrogenated amorphous carbons (a-C:H) to tetrahedral amorphous carbon (ta-C). The measurements are performed using the 3 omega method. They show that thermal conduction is governed by the amount and structural disorder of the sp(3) phase. If the sp(3) phase is amorphous, K scales linearly with the C-C sp(3) content, density, and elastic constants. Polymeric and graphitic films have the lowest K (0.2-0.3 W/mK), hydrogenated ta-C:H has K similar to 1 W/mK, and ta-C has the highest K (3.5 W/mK). If the sp(3) phase orders, even in small grains such as in micro- or nanodiamond, a strong K increase occurs for a given density, Young's modulus, and sp(3) content. (c) 2006 American Institute of Physics.