Hot-carrier energy-loss rates in GaAs/AlxGa1−xAs quantum wells

Abstract

We present a systematic study of the cooling of hot carriers in undoped, n-type doped, and p-type doped GaAs/${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As quantum wells of different well widths by time-resolved luminescence spectroscopy. The energy loss of the carriers due to interaction with optical phonons is independent of dimensionality and well width. The energy loss of electrons is highly reduced at all excitation densities compared with a simple theory of the interactions; for holes, the energy loss comes close to theory at low excitation density. The reduction of the energy-loss rate by optical-phonon scattering cannot be explained by screening or degeneracy but rather is consistent with a hot-phonon effect. The energy-loss rate due to deformation-potential scattering with acoustical phonons increases with decreasing well width.