Hot Electron Relaxation in Quantum Wells

ABSTRACTHot electron relaxation in bulk semiconductors has been studied for several decades, but only through recent advances in crystal growth has it become possible to investigate the ther-malization of hot quasi-two-dimensional carriers in quantum wells. These same advances have opened the possibility of constructing various semiconductor devices which rely on hot electrons for their operation. We discuss experimental results on the energy relaxation of hot electrons in GaAs/AlGaAs quantum wells. The experiments make use of optical spectroscopy for determining the carrier distribution. In particular, steady-state hot photoluminescence measurements have been employed with modulation-doped quantum wells in order to minimally perturb the system by the photoexcited carriers. Both the relaxation of very energetic electrons and the cooling of a hot thermalized carrier distribution are considered. The quantum well results are compared to results from similar experiments with bulk GaAs.