Abstract

The thermoreflectance technique is one of the few methods which can measure thermal diffusivity of thin films as thin as 100 nm or thinner in the cross-plane direction. The thermoreflectance method under rear-heat front-detect configuration is sometimes called ultrafast laser flash method because of its similarity to laser flash method. Up to now it has typically only been possible to attempt to evaluate the interfacial thermal resistance between the thin films by preparing and measuring several samples with different thicknesses. In this study, a method to directly determine interfacial thermal resistance by a single measurement of a thin film on substrate is represented, by analyzing the shape of thermoreflectance signals with analytical solutions in frequency domain and time domain. Thermoreflectance signals observed from metallic thin films on sapphire substrate with different thickness steps were analyzed by Fourier analysis and fitted by analytical equations with four parameters: heat diffusion time across the first layer, ratio of virtual heat sources, characteristic time of cooling determined by interfacial thermal resistance and relative amplitude of the signal. Interface thermal resistance between the thin film and substrate was able to be determined reliably with smaller uncertainty.

中文翻译：

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同时测量热扩散率和界面热阻的傅里叶变换超快激光闪光方法的发展

摘要

热反射技术是少数能够测量厚度为100 nm或更薄的薄膜在横截面方向上的热扩散率的方法之一。后热前探测配置下的热反射法有时被称为超快激光闪光法，因为它与激光闪光法相似。到目前为止，通常只能通过制备和测量几个不同厚度的样品来尝试评估薄膜之间的界面热阻。在这项研究中，提出了一种通过单次测量基板上薄膜来直接确定界面热阻的方法，通过频域和时域解析解分析热反射信号的形状。通过傅立叶分析对不同厚度台阶的蓝宝石衬底上的金属薄膜观察到的热反射信号进行分析，并通过具有四个参数的解析方程进行拟合：第一层的热扩散时间、虚拟热源的比例、界面热确定的冷却特征时间。电阻和信号的相对幅度。能够以较小的不确定性可靠地确定薄膜和基板之间的界面热阻。