Femtosecond optical measurement of hot-carrier relaxation in GaAs, AlGaAs, and GaAs/AlGaAs multiple quantum well structures

Abstract
The ultrafast relaxation of photoexcited GaAs, AlGaAs, and GaAs/AlGaAs quantum well structures has been studied using the equal-pulse correlation technique. Improvements in experimental method now allow extraction of decay times directly from the measured transmission through optically thin samples. Two or three distinct exponential decays are resolved for each material, with the fastest time constant measured to be ∼40 fs in each case. A tentative explanation of the data in terms of known scattering processes is given.