Resonant Rayleigh scattering by excitonic states laterally confined in the interface roughness of GaAs/AlxGa1-xAs single quantum wells

A systematic study of resonant Rayleigh scattering (RRS) in semiconductor single quantum wells (QW's) is reported. The QW's were grown under different conditions leading to different interface roughness. High spatial and spectral resolution photoluminescence (PL) and PL-excitation (PLE) measurements revealed that the electronic configuration of the wells is very sensitive to the growth conditions. RRS and multichannel PLE, which can be related to the absorption, were measured simultaneously in order to study the redshift of the RRS with respect to the absorption. The dependence of this shift on the full width half maxima of the transitions studied showed remarkable differences depending on the Interface roughness profile. RRS intensity was found to be very sensitive to the inhomogeneous broadening of the transitions. The temperature dependence of RRS from 1.4 to 40 K is also reported. The decrease in the intensity and in the redshift between RRS and PLE found in the experiment when temperature is raised can be explained in terms of thermal detrapping of laterally confined excitons.