Photothermal Deflection Experiments: Comparison of Existing Theoretical Models and Their Applications to Characterization of $\mathrm{TiO}_{2}$-Based Thin Films

Abstract

A method for determination of thermooptical, transport, and structural parameters of $\mathrm{TiO}_{2}$-based thin films is presented. The measurements were conducted using beam deflection spectroscopy (BDS) and supporting theoretical analysis performed in the framework of complex geometrical optics providing a novel method of BDS data modeling. It was observed that the material’s thermal parameters strongly depend on sample properties determining its photocatalytic activity such as the energy bandgap, carrier lifetime, surface structure, or porosity. Because of that, the fitting procedure of the theoretical dependence into experimental data was developed to determine the sample’s thermal parameters, on the basis of which the information about its structure was further found. The obtained results were compared to those based on geometrical and wave optics approaches that are currently widely used for that purpose. It was demonstrated that the choice of the proper model for data modeling is a crucial point when performing such a type of analysis.