Low Temperature Photoluminescence Signature Of A Two-Dimensional Electron Gas

We report the first observation of a narrow, low temperature photoluminescence peak associated with the presence of a two-dimensional electron gas (2DEG) at a GaAs/AlGaAs heterointerface. The exact physical mechanism giving rise to this emission is not clear. However, based on a large number of samples, its intensity is found to be directly related with the concentration of the electron gas. The temperature and exciting-intensity dependencies of the peak are consistent with a model based on free excitons in GaAs bound to the electron quantum well formed at the heterointerface by the 2DEG.