Thermal transport across a thin film composite due to laser short-pulse heating

Laser short-pule irradiation of silicon-diamond-aluminum thin films is considered and energy transport across the films is modelled using the Boltzmann transport equation. Electron-phonon coupling is adopted to formulate energy transfer across the electron and lattice sub-systems in the aluminum film. Thermal boundary resistance is incorporated at the film interfaces. The transfer matrix method is used to account for the transmittance, reflection and absorption of the incident laser radiation across the films. Equivalent equilibrium temperature is introduced to access energy transport in the films, which represents the average energy of all phonons around a local point when they redistribute adiabatically to an equilibrium state. It is found that equivalent equilibrium temperature increases sharply in the electron sub-system due to electron excess energy gain from the irradiated field. Equivalent equilibrium temperature decays gradually in the lattice sub-system with increasing period due to phonon scattering in the film.