Research On Technology For Thermal Conductivity Measurement Of Thin Films Based On TPS Method

Thin films,as a kind of special material,their thickness are very small,and there are many differences between thin films and common block materials,so it is a challenge to measure thermal conductivity of thin films.Transient plane source(TPS)method provides a feasible scheme for the challenge.In our previous research,the TPS method has been used to measure thermal conductivity of bulk materials accurately.However,due to the particularity of the film material,there are still many problems in measurement of thermal conductivity by using the TPS method.The basic principle for measuring thermal conductivity of thin films has not been understood.The influence of the thermal resistances,the thermal contact resistances,and the background materials on results of measurement has not been studied.The software algorithms for measuring thermal conductivity of thin films have not been developed yet.In order to solve these problems,this thesis aims to study the measurement of thermal conductivity of thin films by using the TPS method.The main contents of the study are the principle,simulation model,software algorithms and experiments.And the main work of this thesis is as follows.1.The technical background of the measurement of thermal conductivity is introduced in this thesis.Then the significance of the measurement of thin films thermal conductivity is stated,and the difference between the main method and the TPS method is compared.Finally,the main purpose and contents are described.2.The basic principle of measuring thermal conductivity of thin films is described by combining the one-dimensional steady-state heat transfer and the TPS method.Besides,the calculation method of the thermal conductivity and the method for determining the difference of interface temperature are obtained.At last,the systematic error in the principle is corrected and the dimensionless time function is simplified.3.The simulation model was established by using the technique of simulation based on COMSOL Multiphysics software.And the possible factors such as the thermal resistances,the thermal contact resistances and the background materials are analyzed numerically.The methods for improving accuracy of the measurement are obtained from the simulation model.4.Moreover,a software scheme of thermal conductivity measurement of thin films is proposed and each module of the software is analyzed in detail based on the original hardware of the research group.5.An experimental system is used to measure thermal conductivity of thin films with a single thickness and different thickness.The result of the experiments show that thermal conductivity of thin films can be measured by the TPS method accurately,but the existence of thermal resistances of thin films and thermal contact resistances in practice will make the measurement result error.The error can be corrected by different methods.6.In the end of this thesis,the full work is summarized,and the problems which are unsolved are proposed.