Theory for the laser-induced femtosecond phase transition of silicon and GaAS

摘要: We analyze he femtosecond instability of the chamond lattice silicon and GaAs, which is induced by a dense electron-hole plasma after excitation very imense laser pulse. obtain that causes an both transverse acoustic longitudinal optical phonons. So, within less than 200fs, atoms are displaced more 1 A from their equilibrium position. The gap between conduction valence band then vanishes symmetries diamond structure destroyed, has important effects on reflectivity second-harmonic generation. After that, crystal melts rapidly because high kinetic energy atoms. Note mis in good agreement with recent experiments done Shand GaAs using pump to excite electron hole probe observe resulting changes atomic electronic structure.