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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. We find that for an electron density of 10 9 cm −2 in a GaAs QW at T = 5K, the X − linewidth due to electron scattering is roughly twice as large as that of the neutral exciton. This reflects both the X − larger interaction matrix elements compared with those of X, and their different dependence on the transferred momentum. Calculated reflection spectra can then be 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.

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