Optical characterization of GaAs/AlAs multiple quantum wells interfaces

The investigation of optical properties in two wide GaAs/AlAs multiple quan tum wells is reported. Molecular beam epitaxy growth interruption method wa s used for both samples. The growth conditions were the same for both, exce pt for the substrate temperature. The excitonic peaks in the photoluminesce nce spectra were observed to be overlapping. Additional information was req uired for a correct interpretation. This was provided by combining photolum inescence excitation measurements with calculated excitonic energies. The c alculation was made by using an envelope function approach, and takes into account weakly strained GaAs layers. From this analysis the presence of dif ferent wells whose widths vary by one monolayer is suggested. The upper lim it in the fluctuations of the well-width was estimated for both samples.