Effect of screening on the electric field dependence of the exciton linewidth due to scattering by ionized impurities in semiconducting quantum well structures

We further investigated the electric field dependence of the exciton linewidth due to scattering by ionized impurities in semiconducting quantum well structures by taking account of the screening of the exciton-ionized impurity interaction by free carriers. We use the screened Coulomb potential for ionized impurity scattering in quantum wells initially proposed by Hess [Impurity and phonon scattering in layered structures, Appl. Phys. Lett. 35 (1979) 484-486]. Results are presented showing how the screening affects the linewidth at different electric fields and well widths. In most cases, the effect of the screening is to reduce the linewidth below its value in the absence of screening for both the cases of elastic and inelastic scattering of the excitons. However, for wide wells and strong electric fields in the elastic scattering case, it is found that the linewidth increases with increasing screening. The reason for this behavior is discussed. We also find that the magnitude of the linewidth differs depending upon the location of the doping layer relative to the well in the presence of an electric field.