Effects of impurities on excitons in a quantum well: A diffusion Monte Carlo study

We study the effect of impurities on the excitonic structure using the diffusion Monte Carlo method. The exciton binding energy and wave function are investigated as functions of the well width and the impurity position. Impurities located at different positions broaden the energy of an exciton level, resulting in an extra peak in the optical spectra mainly due to those impurities at the center of the quantum well. The broadening is more significant for narrow quantum wells. The wavefunctions of the carriers under the impurity potential are also investigated.