基于3-Omega法的各向异性热导率测量

Measurement of Anisotropic Thermal Conductivity Based on the 3-Omega Method

摘要: 本文首先搭建了基于3-omega法的热导率测试系统并结合LabVIEW软件编写了仪器控制程序，在测试电路中使用INA128P仪表放大器芯片实现样品两端电势差的获取，确保了交流信号的准确测量。之后本文基于3-omega法的一维传热模型使用该测试系统对SiO2/Si样品进行了SiO₂薄膜的平面外热导率测量，得到SiO2薄膜的热导率1.3444 W∙m⁻¹∙K⁻¹，验证了该测试系统对交流信号测量的准确性，为进一步实验奠定基础。但是一维传热模型不能满足实际高质量外延薄膜中不同晶向的热导率测量需求，为此本文发展了一种适用于该需求的二维传热模型，基于加热丝不同宽度的设计，宽度更小的加热器可以调节面内焦耳热的输运情况，从而获得面内方向上的热导率。本实验使用该二维传热模型测量了AlN/Al₂O₃样品中AlN薄膜上[1010]，[2110]和[0001]方向的热导率，实验得到AlN薄膜在这三个方向上的热导率分别为7.32 W∙m⁻¹∙K⁻¹，9.57 W∙m⁻¹∙K⁻¹和1.1612 W∙m⁻¹∙K⁻¹。另外实验也进行了COMSOL软件仿真交叉验证。

Abstract: This paper begins by constructing a thermal conductivity testing system based on the 3-omega method and developing an instrument control program using LabVIEW software. In the test circuit, an INA128P instrumentation amplifier chip is employed to amplify the potential difference across the sample’s two ends, ensuring accurate measurement of the alternating current signal. Subsequently, utilizing the one-dimensional heat transfer model based on the 3-omega method, the system is employed to measure the in-plane thermal conductivity of SiO₂ thin films on Si substrates. The obtained thermal conductivity of the SiO₂ film is 1.3444 W∙m⁻¹∙K⁻¹, validating the accuracy of the measurement system for alternating current signals and laying the founda-tion for further experiments. However, the one-dimensional heat transfer model fails to meet the requirements for measuring the thermal conductivity in different crystal directions in actual high-quality epitaxial films. Therefore, this study develops a two-dimensional heat transfer model suitable for such demands. Based on the design of heating wires with different widths, a narrower heater can adjust the transport of in-plane Joule heat, thereby obtaining the in-plane thermal conductivity. Using this two-dimensional heat transfer model, the experiment measures the thermal conductivity of AlN thin films on Al₂O₃ substrates in the [1010], [2110], and [0001] directions. The experiment yields thermal conductivities of 7.32 W∙m⁻¹∙K⁻¹, 9.57 W∙m⁻¹∙K⁻¹, and 1.1612 W∙m⁻¹∙K⁻¹ for the AlN film in these three directions, respectively. Additionally, the ex-periment undergoes cross-validation through simulation using COMSOL software.