We report simulations of the response of InSb, GaAs, and Si to 70-femtosecond laser pulses of various intensities. In agreement with the experiments of Mazur and coworkers, and other groups, there is a nonthermal phase transition for each of these semiconductors above a threshold intensity. Our simulations employ tight-binding electron-ion dynamics (TED), a technique which is briefly described in the text. In the experimental pump-probe observations, the dielectric function ε (ω) and the second-order susceptibility χ(2) can be measured. These same quantities can be calculated during a TED simulation, and there is good agreement in the behavior with respect to both time and frequency. The simulations provide much additional microscopic information which is experimentally inaccessible: for example, the time-dependence of the atomic pair-correlation function, electronic energy bands, occupancies of excited states, kinetic energy of the atoms, and excursions of atoms from their initial positions.
|Original language||English (US)|
|Number of pages||15|
|Journal||Proceedings of SPIE - The International Society for Optical Engineering|
|State||Published - Jan 1 2001|
|Event||Ultrafast Phenomena in Semiconductors V - San Jose, CA, United States|
Duration: Jan 25 2001 → Jan 26 2001