Excitons bound at interacting acceptors in ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs quantum wells

We have studied the effect of increasing acceptor concentration (between ${10}^{16}$ and ${10}^{18}$ ${\mathrm{cm}}^{\mathrm{-}3}$) on bound excitons (BE’s) using steady-state photoluminescence (PL) and PL excitation spectroscopy. With increasing doping concentration, an additional peak is observed on the low-energy side of the principal neutral acceptor BE. This peak is associated with BE’s formed by excitons bound at interacting acceptors, similar to the undulation spectra observed at high acceptor doping in different bulk materials, such as ZnTe, InP, and GaP. The exciton-impurity complexes are formed as the average distance between the acceptor impurities decreases with increasing doping concentration. The dependence of the optical properties of this exciton on temperature, excitation intensity, and magnetic field is presented. © 1996 The American Physical Society.