Ultrafast hole-lattice thermalization in GaAs quantum wells

We study the thermalisation of optically excited cold holes in GaAs quantum wells using time-resolved femtosecond pump-probe measurements. After optical excitation at the lowest heavy-hole transition, hole-lattice thermalisation via LO-phonon absorption is associated with inter-valence band scattering into the lowest light-hole subband. The temperature dependence of the inter-valence band scattering rate indicates a linear dependence on the LO-phonon occupation number and is in good agreement with theory.