Decoupling thermal properties in multilayered systems for advanced thermoreflectance experiments
Tao Chen, Puqing Jiang
Abstract
Thermoreflectance techniques, such as time-domain thermoreflectance (TDTR), frequency-domain thermoreflectance (FDTR), and the square-pulsed source (SPS) method, are powerful tools for characterizing thermal properties in bulk and thin-film materials. However, accurately interpreting their signals remains challenging due to intricate interdependencies among experimental variables. This study introduces a systematic framework based on singular-value decomposition (SVD) to decouple these interdependent parameters and enhance the reliability of thermal property extraction. By applying SVD to the sensitivity matrix, we identify key parameter combinations and establish essential dimensionless numbers that govern thermoreflectance signals. The framework is applied to a $\mathrm{Ga}\mathrm{N}/\mathrm{Si}$ heterostructure, where the performance of TDTR, FDTR, and SPS are evaluated. Results show a high degree of consistency across all three techniques, with the improved understanding enabling precise and simultaneous extraction of up to seven key thermal properties, including thermal conductivity, heat capacity, and interfacial thermal conductance of the $\mathrm{Ga}\mathrm{N}/\mathrm{Si}$ multilayer system. This framework not only improves the precision of thermoreflectance measurements but also lays a foundation for advanced thermal metrology in both research and industrial applications.