Level repulsion in nanophotoluminescence spectra from single GaAs quantum wells

In a recent paper, Intonti et al. attributed [Phys. Rev. Lett. $87,$ 076801 (2001)] a 3-meV peak in the autocorrelation spectrum of low-temperature nanophotoluminescence spectra of a single disordered GaAs quantum well to level repulsion, i.e., to the statistical analog of an avoided crossing due to overlapping wave functions in the disorder potential. Our data, which reproduce their findings very nearly, are taken to an additional test employing filter functions, which clearly shows that the 3-meV peak is associated with low-energy states—in striking contrast to the level repulsion scenario. By a careful analysis of the high-energy states, however, we are able to identify a second peak around 1.5 meV which we attribute to level repulsion. The experiments are compared with simple model calculations, which support our interpretation.