反问题方法在3ω法测量薄膜热导率中的应用  

Application of the inverse method in the 3ω method for measuring the thermal conductivity of thin films

作　　者：华钰超 曹炳阳[1] Yuchao Hua;Bingyang Cao(Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Department of Engineering Mechanics,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学工程力学系热科学与动力工程教育部重点实验室

出　　处：《科学通报》2019年第33期3510-3514,共5页Chinese Science Bulletin

基　　金：国家自然科学基金(51825601,51676108,51321002,51906121);博士后创新人才计划(BX20180155);中国博士后科学基金(2018M641348)资助

摘　　要：数值计算证明, 3ω方法结合有限元方法与反问题方法,能够同时确定基底材料与薄膜的相关热物性.基底上薄膜的热导率可以获得很高的测量精度,而且几乎不受测量截止频率的影响;热扩散率的测量精度则相对较低,但随着测量截止频率增加,其测量精度会得到改善.使用上述方法得到了硅基底上二氧化硅薄膜的热导率.得到硅基底的热导率为142.1 W/(m K),相对误差约为2%,二氧化硅薄膜的热导率为1.01 W/(m K),相对误差约为2%,与公认的测量值相符.Planar nano-materials generally refer to samples that are extremely thin in the direction of thickness, such as nanofilms,graphene, and superlattice. They are of great importance in various fields, including transistors, thermoelectrics, and optoelectronics, etc. In practice, materials’ thermal transport characteristics often play a crucial role in applications. More importantly, due to the confinement in the direction of thickness, the mechanisms of thermal transport process in planar nano-materials become very different from those at the macroscale. For example, the effective lattice thermal conductivities of nanofilms are always highly dependent on their thickness, since phonon coherence, ballistic transport, and boundary scattering effects could occur in this case. Therefore, probing thermal transport properties of planar materials has been a research hotspot in both the research and industrial communities. The 3ω method has been proven to be a powerful tool that can measure the thermal conductivities of planar materials effectively. Particularly for a thin film on a substrate,the differential 3ω method was developed. In this scheme, it is necessary to determine the thermal properties of substrate materials in the first step. Thus, a reference sample should be measured in addition to the target sample, which not only increases the complexity of measurement but also reduces the measurement accuracy of the thin film’s thermal transport properties. In the present work, we used the numerical simulations to demonstrate that in the 3ω method the combination of finite element method(FEM) and inverse problem method can derive the thermal properties of thin film and substrate simultaneously. It was found that the thermal conductivities could be determined accurately despite the cutoff frequency of measurement, whereas the thermal diffusivities’ accuracy could be improved with increasing cutoff frequency of measurement. Furthermore, as a test, the thermal conductivities of silicon dioxide(SiO2) thin film on th

关 键 词：3ω方法 反问题方法 热导率 薄膜 

分 类 号：TB3[一般工业技术—材料科学与工程]