Inter- and intra-subband relaxation of hot electrons in GaAs/AlGaAs quantum wells

Abstract

In this work, we have studied the inter- and intra-subband scattering of hot electrons in quantum wells using the hot electron–neutral acceptor luminescence technique. We have observed direct evidence of the emission of confined optical phonons by hot electrons excited slightly above the n=2 subband in GaAs/Al 0.37Ga 0.63As quantum wells. Scattering rates of photoexcited electrons via inter- and intra-subband LO phonon emission were calculated based on the dielectric continuum model. We found that, for wide wells with the Al composition of our experiments, both the calculated and experimental results suggest that the scattering of the electrons is dominated by the confined LO phonon mode. In the calculations, scatterings among higher subbands are also dominated by the same type of phonon at well width of 10 nm.