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| Measurement of phonon mean free path of single crystal silicon based on TDTR |
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WANG Xinwei1,2,3, ZHANG Zhongyin4, SUN Fangyuan2, XIONG Xue2,3, CHEN Zhe2, JIANG Yuyan2, TANG Dawei4
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(1.College of Pipeline and Civil Engineering in China University of Petroleum (East China), Qingdao 266580, China;2.Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China;3.University of Chinese Academy of Sciences, Beijing 100049, China;4.Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China)
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| Abstract: |
| The phonon ballistic transport phenomena were investigated in single crystal silicon under different temperatures by changing the pump beam diameter and modulation frequency based on the time-domain thermoreflectance(TDTR), and thus indirectly the mean free path(MFP) was obtained in silicon. It is found that the room temperature phonon MFP in silicon can reach 1.5 μm, and the phonon MFP in silicon increases at lower temperature, up to 40 μm at 80 K. The size effects in thermal conductivity are enhanced as the contribution of the phonon ballistic transport increases for the same sample under the lower temperature. When the film materials and their interfacial thermal resistance were characterized based on TDTR, it is better to choose the bigger pump beam diameter and smaller modulation frequency to avoid the size effect during heat transfer, and reduce the effect of the phonon ballistic transport on the measurement value. |
| Key words: thermal conductivity TDTR size effect ballistic transport phonon mean free path |
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