Ultrafast internal thermalization of photoexcited carriers in polar semiconductors (Invited Paper)
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We present a combined experimental and theoretical study of the ultrafast internal thermalization of high energy carriers created by laser excitation. Luminescence up-conversion is used to monitor the spectral and temporal evolution of the photoexcited carrier distributions with a time resolution of about 100 fs. A Monte Carlo simulation joined with a molecular dynamics approach is then used to interpret the experimental results. We show that the coulomb interaction among carriers is responsible for the initial ultrafast thermalization. The simulation allow us to distinguish between binary carrier-carrier collisions and plasmon losses and reconcile the results obtained with time resolved vs. c.w. hot (e, angstroms) luminescence.