ABSTRACT
By using an optical time of flight technique we have investigated the ambipolar diffusion in GaAs/AlGaAs quantum wells with a varying number of AlAs monolayers (0-5) inserted at the center of the well for different Al-concentrations in the barrier. The AlAs layers push the electron hole wavefunctions into the AlGaAs barriers and result in a reduction of the ambipolar diffusivity particularly in the temperature range between 40 K and 90 K The decrease of the ambipolar diffusivity can be correlated to the increasing influence of interface roughness scattering at the quantum well interfaces and the AlAs-layers.
