Temperature and excitation intensity dependencies of the photoluminescence spectra of GaAs/(AlGa)As disordered superlattices

The temperature and excitation intensity dependencies of the photoluminescence (PL) spectra of GaAs/Al0.3Ga0.7As superlattices (SL's) having randomly distributed well widths are studied. Our results indicate that the electronic properties of disordered SL's are similar to those of other disordered semiconductors: at low energies the electronic states are essentially localized, while at higher energies they are extended. Further, the PL spectra feature a disorder-induced fine structure, and they shift to the red with T simply following the reduction of the band gap. The PL efficiency shows a weaker decrease with increasing T than the ordered SL. The dependence of the PL spectra on the excitation intensity shows an anomalous behavior of the disorder-induced fine-structure recombination lines.