Non-thermal laser induced ordering and plasma lifetime

Abstract

The phonon frequency of partially annealed ion-implanted amorphous silicon is shifted down up to 10 cm^-1 from the value for crystalline silicon. We interpret the down shifted values as representing partially annealed intermediate states. Conventional melting models cannot explain the observed shift. Mechanisms for the gradual reordering include assistance from bond-breaking and vacancy-screening by plasmons. A calculation on the upper limit of the plasmon life-time for covalent crystals is presented. Results suggest that excited e-h pairs involved in plasma oscillation can be long-lived in comparison to the single particle electron-phonon interaction.