Femtosecond hot-carrier energy relaxation in GaAs

Abstract

Excited carrier dynamics in GaAs and Al0.2Ga0.8As are investigated using femtosecond pump and continuum probe techniques. We observe absorption spectral hole burning arising from excited carriers generated by transitions from the split-off band as well as the heavy- and light-hole bands. Transient absorption saturation measurements indicate that the initial nonthermal carrier distribution thermalizes on a time scale of several tens of femtoseconds.