A combined 2ω/3ω method for the measurement of the in-plane thermal conductivity of thin films in multilayer stacks: Application to a silicon-on-insulator wafer

This study focuses on establishing and validating a method to accurately measure the in-plane thermal conductivity of very conductive thin films, such as single-crystal metals or semiconductors, 2D and nanostructured materials. By integrating both 2ω and 3ω measurements, the method is rendered insensitive to the superficial thermal boundary resistance of the insulating overlayer, enabling precise estimation of the in-plane thermal properties of conductive films grown on top of substrates or multilayer stacks. The proposed technique is applied to analyze the thermal conductivity of a silicon-on-insulator stack with a top layer consisting of a 340 nm thick film of monocrystalline silicon. Measurements are conducted within a temperature range spanning from 250 to 325 K. The results confirm the method’s capability to correctly assess the thermal conductivity decrease of the silicon film compared to bulk value, demonstrating its reliability for the thermal characterization of conductive thin films.