Auger heating of carriers in GaAs/AlAs heterostructures

The photoluminescence of GaAs/AlAs multiple quantum wells structures under optical ps excitation is investigated for carrier densities in the range 10(18)-4 x 10(19) cm(-3) with frequency and time-resolved spectroscopic techniques. The measurements give a direct evidence of the occurrence in the sample of carrier heating. This energy up-conversion gives rise to photoluminescence from the states near the Fermi level whose intensity and time evolution depend on the carrier density in a strongly non-linear way. The observed behaviour can be explained introducing in the carrier dynamics an up-conversion mechanism due to Auger-like processes.