Measuring thermal properties of materials is not only of fundamental importance in understanding the transport processes of energy carriers (electrons and phonons) but also of practical interest in developing novel materials with desired thermal conductivity for applications in energy, electronics, and photonic systems. Over the past two decades, ultrafast laser-based time-domain thermoreflectance (TDTR) has emerged and evolved as a reliable, powerful, and versatile technique to measure the thermal properties of a wide range of bulk and thin film materials and their interfaces. This tutorial discusses the basics as well as the recent advances of the TDTR technique and its applications in the thermal characterization of a variety of materials. The tutorial begins with the fundamentals of the TDTR technique, serving as a guideline for understanding the basic principles of this technique. A diverse set of TDTR configurations that have been developed to meet different measurement conditions are then presented, followed by several variations of the TDTR technique that function similarly as the standard TDTR but with their own unique features. This tutorial closes with a summary that discusses the current limitations and proposes some directions for future development.
Simultaneous Measurement of Thermal Conductivity, Heat Capacity, and Interfacial Thermal Conductance by Leveraging Negative Delay-Time Data in Time-Domain Thermoreflectance
Thermal Characterization of Buried Interfaces in Multilayer Heterostructures via TDTR with Periodic Waveform Analysis
School of Energy and Power Engineering, Huazhong University of Science and Technology（华中科技大学能源与动力工程学院）；School of Mechanics and Engineering Science, Peking University（北京大学力学与工程科学学院）
Ultralow and Tunable Thermal Conductivity of Parylene C for Thermal Insulation in Advanced Packaging
School of Software & Microelectronics, Peking University（北京大学软件与微电子学院）；School of Integrated Circuits and Beijing Advanced Innovation Center for Integrated Circuits, Peking University（北京大学集成电路学院及北京集成电路先进创新中心）
Measurements and Numerical Calculations of Thermal Conductivity to Evaluate the Quality of β-Gallium Oxide Thin Films Grown on Sapphire and Silicon Carbide by Molecular Beam Epitaxy
报道了一种在c面蓝宝石和4 H-SiC衬底上用分子束外延（MBE）生长的β-Ga 2 O3薄膜的低热导率研究方法。我们将实验值与数值预测进行比较，以解释薄膜中边界散射和缺陷的影响。我们使用时域热反射（TDTR）进行实验，密度泛函理论和玻尔兹曼输运方程的热导率计算，和扩散失配模型TBC预测。实验的热导率约为3倍小于那些计算的类似大小的完美的Ga 2 O 3晶体。当在计算中考虑晶界、镓和氧空位以及堆垛层错的存在时，存在约1%的镓空位和106个缺陷/cm的堆垛层错密度的晶体是热导率更接近实验结果的晶体。我们的分析表明，不同类型的缺陷存在于Ga 2 O3晶体，可用于通过减少这些缺陷，从而产生具有更高的热导率的材料，以提高MBE生长的样品的质量的水平。
Thermal conductivity of intercalation, conversion, and alloying lithium-ion battery electrode materials as function of their state of charge
在插入和取出锂时，对于电化学能量储存重要的材料可以经历热导率（$Λ$）和弹性模量（$\it M$）的变化。这些变化是由于演化的固有的热载流子寿命和原子间的键合强度与电极材料的结构转变具有不同程度的可逆性。利用原位时域热反射技术和皮秒声学技术，系统研究了电极材料在循环过程中的转化、嵌入和合金化过程中的$Λ$和$\it M$。插层V $_{2}$ O $_{5}$和TiO $_{2}$表现出非单调可逆$Λ$和$\it M$切换高达1.8倍（$Λ$）和1.5倍（$\it M$）作为锂含量的函数。在第一次锂化时，转化的Fe $_{2}$ O $_{3}$和NiO在$Λ$和$\it M$中经历不可逆衰变。合金化Sb显示出$Λ$在脱锂状态（18 W m $^{-1}$ K $^{-1}$）和锂化状态（<1 W m $^{-1}$ K $^{-1}$）之间的最大和部分可逆的数量级的量值切换。不可逆的$Λ$归因于循环过程中大量体积变化导致的结构降解和粉碎。这些发现为电池设计的重要性循环过程中电极材料的热和机械性能演变提供了新的理解，并且还指出了形成具有热切换性能的材料的途径。
Study on Thickness and Temperature Dependence of Thermoelectric Properties in SnS Nanofilms
School of Energy and Power Engineering, Dalian University of Technology（大连理工大学能源与动力学院）；Dalian University of Technology（大连理工大学）；School of Physics and Technology, Nanjing Normal University（南京师范大学物理科学与技术学院）；Nanjing Normal University（南京师范大学）
