Measurement Technique And Application Of Thermophysical Properties Of Continuous Wave Laser Frequency Domain Thermoreflectance

With the continuous miniaturization of nanostructures and devices,interfacial thermal resistance has become the main factor affecting the heat transport process.Therefore,the characterization of interfacial thermal resistance is of great significance for the development and application of nanostructures and devices.In this paper,a continuous wave frequency domain thermoreflectance experimental system is established.Based on the characterization of the thermal conductivity of the thin film and the thermal resistance at the solid-solid interface in multilayer nanostructures,the thermal conductivity of liquid and the thermal resistance of solid-liquid interface are characterized.A theoretical model for the heat conduction of multilayer films under laser thermal excitation is established.The thermal impedance of the sample surface is obtained by using the transmission line method.The theoretical solution of the temperature fluctuation is obtained by using the inverse Laplace transform and the inverse Hankel transform.The simulated annealing algorithm is used to fit the theoretical solution and experimental data,and the thermal parameters such as thermal conductivity and interfacial thermal resistance can be obtained.The heat transport process in multilayer nanostructures is studied by this system.The thermal conductivity of sapphire,quartz glass and silicon in the two-layer structure and the interfacial thermal resistance with the aluminum transducer are obtained.In the three-layer structure,the thermal conductivity and interfacial thermal resistance of hafnium oxide films with different thickness are studied.The results show that the thermal conductivity increases with the increase of the film thickness,showing a scale effect.The interfacial thermal resistance is in the same order as the thermal resistance of hafnium oxide thin films,and its influence on the heat transport process cannot be ignored.Based on the measurement of thermal conductivity and interfacial thermal resistance of nano films,an experimental platform and bidirectional heat transport model are established to measure the thermal conductivity of liquid and interfacial thermal resistance of solid-liquid interface.Through theoretical calculation,the effect of thermal conductivity of window material on experimental results is studied,and quartz glass is selected as window material.The thermal conductivity and interfacial thermal resistance of water,ethanol and hexadecane are obtained by using the system and bidirectional thermal transport model.The contact angle of the three liquids on the surface of aluminum transducer is measured.It is found that the interfacial thermal resistance and contact angle showed a corresponding relationship.The larger the contact angle,the larger the interfacial thermal resistance.In order to verify the experimental results,molecular dynamics simulation is used to study the heat transfer process at the aluminum/water solid-liquid interface.The interfacial thermal resistance is obtained in the same order as the experimental value.By changing the interfacial force to change the wettability of the interface,it is found that the highly wetting solid can more effectively coupling the energy of low frequency phonons and make the interfacial thermal resistance smaller.