Thermoreflectance profile analysis and multiparameter 3D fitting model applied to the measurement of thermal parameters of thin film materials

We describe a pump-probe technique for measuring the thermal properties of homogenous and isotropic thin films. We show how a single noncontact measurement as function of the position between pump and probe beams can determine simultaneously and with high accuracy the thermal diffusivity, the thermal conductivity of a thin layer and the thermal boundary resistance between the thin film and the semi-infinite substrate. We determine numerically the heat flow in a layered sample pumped by a modulated Gaussian laser beam taking into consideration the thermal boundary resistance. Experimental results are deducted from measurements on a fused silica substrate covered by a 150 nm of gold. These results are validated by the literature values and those obtained by applying the asymptotic behavior methodology developed by Fretigny et al. We present the statistical errors of the two methods and the sensitivity of the fitting model to various thermal properties. (paper)