Intersubband scattering and thermalization of electrons in GaInAs/AlInAs quantum wells studied by femtosecond infrared spectroscopy

Summary form only given. The ultrafast dynamics of carriers in low-dimensional semiconductors is governed by inter- and intrasubband scattering processes resulting from carrier-carrier and carrier-phonon interactions. In this paper, we report femtosecond studies of electron dynamics occurring after optical excitation to a higher conduction subband in GaInAs/AlInAs quantum wells. Our results demonstrate a lifetime of the n=2 conduction subband of 1 ps and give the first direct insight into the relatively slow electron thermalization after intersubband excitation.