Binding energy of negatively charged exciton in a semiconductor quantum well: the role of interface defects

We present a model to take into account the interface defects contribution on the binding energy of charged exciton in GaAs/Al$_{0.3}$Ga$_{0.7}$As quantum wells. The dependence of the binding energy gain and of the trion size on the quantum well width are variationally calculated. We show that the trion is more sensitive to interface defects than the exciton.