Thermophysical characterization of a CuO thin deposit

CuO thin deposits on a tungsten carbide (consisting of 9% cobalt) substrate are obtained by physical vapor deposition (PVD) at ambient temperature. The longitudinal thermal conductivity as well as the thermal contact resistance at the deposit-substrate interface are investigated. A periodic photothermal experiment based on infrared radiometry is implemented. The amplitude between the periodic heat flux applied on the sample and the average temperature on the heated area are measured over a low frequency range. The method does not require the absolute measurement of these two quantities given that the thermal properties of the substrate are known. Scanning electron microscopy observations show strong anisotropy and columnar structure of the deposits. Moreover, the chemical composition of the films is obtained using the Auger technique. Cobalt diffuses from the substrate toward the deposit during the deposition process. It is demonstrated that the measured thermal conductivity of the CuO layer mainly rests on the microstructure of the layer instead of the roughness of the sample.