Field evaporation of semiconductors assisted by nonequilibrium phonon excitations
Résumé
Laser-assisted field evaporation of materials is often interpreted as an equilibrium phenomenon that can be described in terms of a thermally assisted process due to the increase of the lattice temperature defined for equilibrium phonon distribution. Our simulations, taking into account nonequilibrium phonon distribution, produced by femtosecond laser radiation, and coupled carrier-phonon kinetics in the sample, show that the evaporation process is assisted by hot phonons. An out-of-thermal-equilibrium phenomenon on the picosecond time scale is thus demonstrated in the case of femtosecond-laser-assisted field evaporation of semiconductors. It is experimentally confirmed by atom-probe measurements using an original double-pulse correlation setup.