飞秒激光抽运探测热反射法测量微纳米结构界面热阻

发布时间：2018-02-09 14:18

本文关键词： 飞秒激光抽运探测热反射非平衡热输运双相滞模型纳米薄膜敏感度分析热导率界面热导　出处：《中国石油大学(华东)》2015年硕士论文　论文类型：学位论文

【摘要】：在本研究中,对飞秒激光抽运探测热反射实验系统进行了改进,使用更高倍频效率的BIBO晶体;使用低通滤波器降低了激光自身重复频率对信号测量的干扰;构建CCD摄像显微系统,实现抽运光和探测光光斑的精确对准,同时还可实现样品最佳测量点的选取。采用matlab编程模拟计算了微纳米尺度下的超短非平衡热输运过程,即抛物两步模型和双相滞模型下激光加热物体的温度分布。非平衡热输运过程的模拟计算结果验证了金属薄膜被激光加热后非平衡现象的存在,分析了电—声子耦合因子的大小对电子、声子的温度影响。双相滞模型中分别模拟计算了在固定时刻不同导热方式下物体沿厚度方向的温度分布,以及加热面和底面在不同导热方式下的温度随时间的演化情况。根据傅里叶导热模型对拟合过程中的输入参数(调制频率、激光光斑、薄膜厚度、热导率、界面热导)进行了敏感度分析,为测量具体样品时调制频率和激光光斑大小的选择提供了依据,提高了测量精确度。利用飞秒激光抽运探测热反射实验系统测量了两层和三层不同纳米结构下多种材料的热导率和界面热导,测量结果均与已有相关文献报道值吻合。三层样品Al-HfO_2-Si的测量结果显示,随着中间层HfO_2薄膜厚度的增加,有效界面热导不断减小,对测量结果进行分析得出界面热导和薄膜热导率数值大小和中间层HfO_2薄膜厚度有关。
[Abstract]:In this study, the experimental system of femtosecond laser pumped detection of heat reflection is improved, the BIBO crystal with higher frequency efficiency is used, and the interference of laser self-repetition frequency to signal measurement is reduced by using low-pass filter. A CCD camera microscope system was constructed to realize the accurate alignment of pumping light and detecting spot, and to select the best measuring point of the sample. The ultrashort non-equilibrium thermal transport process at the micro and nanometer scale was simulated and calculated by matlab programming. That is, the temperature distribution of the laser heated object under the parabolic two-step model and the two-phase hysteresis model. The simulation results of the non-equilibrium heat transfer process verify the existence of the non-equilibrium phenomenon after the metal film is heated by laser. The effect of the electron-phonon coupling factor on the temperature of electrons and phonons is analyzed. The temperature distribution along the thickness of the body in different heat conduction modes at a fixed time is simulated in the two-phase hysteretic model. According to the Fourier conduction model, the input parameters (modulation frequency, laser spot, film thickness, thermal conductivity) of the fitting process are obtained. The sensitivity analysis of interface thermal conductivity provides a basis for the selection of modulation frequency and laser spot size when measuring specific samples. The thermal conductivity and interface thermal conductivity of a variety of materials with two and three layers of different nanostructures were measured by femtosecond laser pumped detection heat reflection experimental system. The measured results are in good agreement with those reported in previous literatures. The Al-HfO_2-Si measurements of three layers of samples show that the effective interfacial thermal conductivity decreases with the increase of the thickness of the HfO_2 film in the middle layer. The results show that the interfacial thermal conductivity and the thermal conductivity of the films are related to the thickness of the interlayer HfO_2 films.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;TN249

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