Complete thermal characterization of film-on-substrate system by modulated thermoreflectance microscopy and multiparameter fitting

Modulated thermoreflectance microscopy is applied to a complete thermal characterization of a thin film of gold (78 nm) or YBaCuO (300 nm) on a LaAlO3 substrate. The phase profile, measured at several modulation frequencies covering an appropriate range, is fitted with a rigorous thermal diffusion model. This leads to a simultaneous estimation of the thermal diffusivities of the film and the substrate, as well as of the thermal film/substrate boundary resistance. The estimated values for the gold film sample are, respectively, 4.3×10−6 m2 s−1 (substrate diffusivity), 1.0×10−4 m2 s−1 (film diffusivity), and 1.0×10−8 m2 KW−1 (thermal boundary resistance), while for the thermally anisotropic YBaCuO film sample are, 4.1×10−6 m2 s−1, 3.5×10−6 m2 s−1 (in-plane diffusivity), and 8.0×10−8 m2 KW−1, respectively.