ABSTRACT
We implement optical spectroscopy to study charged excitons (trions) in modulation doped GaAs/AlGaAs quantum wells. We observe several types of trions: the heavy and light-hole negatively charged exciton, the positively charged exciton and the triplet state of the negatively charged exciton. We unambiguously prove the three-body nature of the negatively charged exciton by studying its shakeup processes. We discuss the structure of different trions at zero and high magnetic fields.
