Theory of neutral and charged exciton scattering with electrons in semiconductor quantum wells

Electron scattering on both neutral (X) and charged (X-) excitons in quantum wells is studied theoretically. A microscopic model is presented, taking into account both elastic and dissociating scattering. The model is based on calculating the exciton-electron direct and exchange interaction matrix elements, from which we derive the exciton scattering rates. Scattering by electrons is found to be an efficient process even for very low electron densities. In particular, the charged exciton linewidth due to electron scattering is larger than that of the neutral exciton, partially because of the larger contribution from the dissociating process. Calculated reflection spectra are then obtained by considering the three electronic excitations of the system, namely, the heavy-hole and light-hole 1S neutral excitons, and the heavy-hole 1S charged exciton, with the appropriate oscillator strengths.