Quantum kinetics regime during and immediately after laser excitation of semiconductors

We investigated carrier dynamics in the semiconductor GaAs, during and just after creation by ≈ 30 fs laser pulses, much shorter than the phonon and plasma time scales. We observed a quasi-instantaneous spread of the carrier population in momentum-energy space, that is not even qualitatively consistent with Boltzmann kinetics. The observations are, however, in qualitative agreement with quantum kinetic theories of carrier-carrier and carrier-phonon scattering.