Hot photoexcited electrons and exciton kinetics in GaAs

Exciton-polariton photoluminescence kinetics under short-pulse excitation in pure epitaxial GaAs has been investigated. The observed delayed onset of the polariton luminescence is attributed to the energy relaxation of polaritons and photoexcited electrons. The electron energy relaxation is controlled by inelastic impurity scattering. In an ultrapure sample (ND ∼ 1012cm-3) the maximum of luminescence is reached after a considerable delay of 4 ns. At high repetition rate the next excitation pulse causes a fast quenching of polariton luminescence in the vicinity of exciton resonance due to heating of excitons by photoexcited hot electrons. A model of exciton luminescence kinetics involving exciton-electron interaction has been proposed