EXCITON LOCALIZATION, PHOTOLUMINESCENCE SPECTRA, AND INTERFACE ROUGHNESS IN THIN QUANTUM-WELLS

The combination of conventional photoluminescence (PL), PL-excitation (PLE), and micro-FL spectroscopies is used to study the influence of i nterface roughness on luminescence properties of thin GaAs/Al0.3Ga0.7A s single quantum wells (QWs). The QWs were prepared under different gr owth conditions, resulting in different interface roughness. We discus s the splitting of PL spectra into two (or more) main lines, the prono unced fine structure of the micro-FL spectra and the low-energy shift of the PL lines with respect to the PLE spectrum in terms of a phenome nological interface model. For low temperatures exciton localization d ue to interface fluctuations with different length scales determines m ost of the luminescence features. One consequence is a strong suppress ion of the PLE signal on the low-energy side of the spectra. Therefore in this case the PLE spectrum cannot be used as a measure for the abs orption strength or as an indicator for impurity bound excitons.