Investigation into pulse laser heating of nanoscale Au film using dual-phase-lag model

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.