Ultrafast Electron–Phonon Coupling at Metal-Dielectric Interface |
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Authors: | Qiaomu Yao Liang Guo Vasudevan Iyer |
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Affiliation: | School of Mechanical Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, USA |
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Abstract: | Energy transfer from photo-excited electrons in a metal thin film to the dielectric substrate is important for understanding the ultrafast heat transfer process across the two materials. Substantial research has been conducted to investigate heat transfer in a metal-dielectric structure. In this work, a two-temperature model in metal was used to analyze the interface electron and dielectric substrate coupling. An improved temperature and wavelength-dependent Drude–Lorentz model was implemented to interpret the signals obtained in optical measurements. Ultrafast pump-and-probe measurements on Au-Si samples were carried out, where the probe photon energy was chosen to be close to the interband transition threshold of gold to minimize the influence of non-equilibrium electrons on the optical response and maximize the thermal modulation to the optical reflectance. Electron-substrate interface thermal conductance at different pump laser fluences was obtained, and was found to increase with the interface temperature. |
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