Theoretical and experimental study of photo-modulated reflectivity detections for transparent film/opaque substrate structures

A photo-modulated reflectivity method is used to evaluate thermal properties of bilayered structures composed of transparent films deposited on opaque substrates. In order to calculate the photo-modulated reflectivity variations of the bilayered structures induced by focused modulated laser irradiations, a 3-D theoretical model is presented. Due to the complexity of the 3-D theory, a finite element method is used to simulate the laser-induced temperature fields, thermoelastic displacement fields and dielectric constant variations, and finally the photo-modulated reflectivities. Then a quantitative investigation of the thermal properties of the transparent films deposited on opaque substrates can be performed by the experimental measurements and theoretical simulations. As examples, the thermal conductivities of ZnO and diamond films deposited on silicon substrates are evaluated and discussed. PACS 44.10.+i; 42.55.-f; 51.70.+f; 68.60.-p