Optical transitions in AlGaAs/GaAs quantum wires on GaAs(6Â 3Â 1) substrates studied by photoreflectance spectroscopy

We present the synthesis and characterization of a system of self-assembling GaAs quantum wires (QWRs) embedded in Alx Ga1−x As barriers grown by molecular beam epitaxy on GaAs(6 3 1)-oriented substrates. We studied the optical transitions in the QWRs as a function of temperature (T) by photoreflectance (PR) spectroscopy. The energy transitions were extracted from the PR spectra employing the third-derivative functional form, and they were compared with the transitions theoretically calculated from both, a model of QWRs with cylindrical geometry and a model of a conventional square quantum well. The results show a good agreement between experimental and theoretical data in the case of the QWR model, and from this comparison we were able to identify up to 12 different transitions in the PR spectra and to study their behavior dependent on temperature.