Nonequilibrium cooling of thermalized electrons and holes in GaAs/AlxGa1−xAs quantum wells

Abstract

We report transient-photoluminescence spectroscopy measurements of photoexcited hot electrons and holes in an undoped 5-nm GaAs/${\mathrm{Al}}_{0.3}$ ${\mathrm{Ga}}_{0.7}$As single-quantum-well heterostructure. After picosecond excitation at 1.75 eV, we find regimes of carrier densities and temperatures where light holes are considerably cooler than electrons, reflecting the fact that the generally assumed thermal equilibrium between electrons and holes is not valid.