Abstract
With the ever decreasing characteristic lengths of nanomaterials, nonequilibrium electron-phonon scattering can be affected by additional scattering processes at the interface of two materials. Electron-interface scattering would lead to another path of energy flow for the high-energy electrons other than electron-phonon coupling in a single material. Traditionally, electron-phonon coupling in transport is analyzed with a diffusion (Fourier) based model, such as the two temperature model (TTM). However, in thin films with thicknesses less than the electron mean free path, ballistic electron transport could lead to electron-interface scattering, which is not taken into account in the TTM. The ballistic component of electron transport, leading to electron-interface scattering during ultrashort pulsed laser heating, is studied here by a ballistic-diffusive approximation of the Boltzmann transport equation. The results for electron-phonon equilibration times are compared with calculations with TTM based approximations and experimental data on Au thin films.
Issue Section:
MICRO/NANOSCALE HEAT TRANSFER—PART
II
Keywords:
ballistic transport,
Boltzmann equation,
electron-phonon interactions,
metallic thin films,
plasma heating by laser,
plasma production by laser,
plasma transport processes,
electron-phonon coupling,
ultrashort pulsed laser heating,
Boltzmann transport equation,
ballistic-diffusive treatment,
electron-interface scattering,
thin films
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