Theory of ultrafast phenomena in laser-excited semiconductors

The study of semiconductor carriers excited by femtosecond laser excitation has proved to be one of the most effective methods of characterization of semiconductors, as well as providing a probe for new physical effects. On the femtosecond time-scale, however, it is not expected that the semiclassical Boltzmann equation will be correct, and a more basic quantum mechanical formulation is required. The formulation of equivalent transport equations from the Schrodinger equation and its variants will be briefly reviewed. Results, using an ensemble Monte Carlo method, for electron-electron and electron-phonon interactions will be presented to show how these studies can be used to investigate the strength of the electron-phonon interaction and how the finite collision duration affects such studies.