Ho Ching-Yen, Tsai Yu-Hsiang, Chen Bor-Chyuan
Department of Mechanical Engineering, Hwa Hsia Institute of Technology, New Taipei City 235, Taiwan.
J Nanosci Nanotechnol. 2013 Oct;13(10):7205-7. doi: 10.1166/jnn.2013.7947.
In this study the thermal field is presented for pulse laser processing of nanoscale Au films. Fourier law is inadequate for describing the heat conduction in nanoscale process due to the boundary scattering and the finite relaxation time of heat carriers. In the regime where the particle description of electrons and phonons is valid, the Boltzmann equation is the most accurate option to model heat transfer in such problems. However, solving the Boltzmann equation is generally difficult due to involving three spatial, three momentums and one time. Dual-phase-lag (DPL) model is averaged over the momentum space and thus involves only spatial coordinates plus time, as in the Fourier equation. Therefore this paper utilizes the dual-phase-lag (DPL) model with scattering boundary condition to study the temperature field for laser processing of nanometer-sized thin films instead of Boltzmann equation. The results obtained from the dual-phase-lag heat conduction model, hyperbolic and parabolic heat conduction equations were compared with the available experimental data to validate the compatibility of the thermal models for analyzing the heat transfer in nanoscale thin film irradiated by laser. The temperature history at different locations of the thin film and the effects of boundary phonon scattering on the normalized temperature were also discussed.
本研究给出了纳米级金膜脉冲激光加工的热场。由于边界散射和热载流子的有限弛豫时间，傅里叶定律不足以描述纳米级过程中的热传导。在电子和声子的粒子描述有效的区域，玻尔兹曼方程是对此类问题中的热传递进行建模的最准确选择。然而，求解玻尔兹曼方程通常很困难，因为它涉及三个空间变量、三个动量变量和一个时间变量。双相滞后（DPL）模型是在动量空间上进行平均的，因此像傅里叶方程一样，只涉及空间坐标和时间。因此，本文利用具有散射边界条件的双相滞后（DPL）模型来研究纳米尺寸薄膜激光加工的温度场，而不是使用玻尔兹曼方程。将双相滞后热传导模型、双曲型和抛物型热传导方程得到的结果与现有的实验数据进行比较，以验证热模型在分析激光辐照纳米级薄膜热传递方面的兼容性。还讨论了薄膜不同位置的温度历程以及边界声子散射对归一化温度的影响。
