Photothermal Evidence of Laterally Inhomogeneous Interfacial Thermal Resistance in Copper-Coated Carbon Samples

In this study, the heat transport in copper–carbon flat model systems was studied by frequency-dependent photothermal radiometry (PTR). The samples consist of Cu films of about 1 μm thickness deposited by magnetron sputtering on vitreous carbon (Sigradur). Particular interest was devoted to the influence of interface defects on the interfacial thermal conductance (or resistance) of the CuC systems. The PTR data were analyzed in the frame of a heat diffusion equation for one- and three-dimensional heat transport. By comparing PTR signals from as-prepared and from heat-treated samples, the lateral inhomogeneities of the interfacial thermal conductance could be quantified. The measured phase differences were analyzed in the scope of a model where a small part of the surface area has a different interfacial thermal conductance than the major part of the surface.