The dependence of the exciton linewidth broadening due to scattering by free carriers on carrier concentration, temperature, and well width, in semiconducting quantum well structures is theoretically studied using a finite confining potential model. The contribution to the linewidth due to ionization scattering of the exciton to the continuum electron-hole states, is included in the present calculations, which is shown to further enhance the importance of free carrier scattering in the broadening of the exciton linewidth. Quasi 3 dimensional features in the very narrow wells due to the finite confinement are also presented and discussed. ©1997 American Institute of Physics.