Optical spectroscopy of self-assembled type II GaSb/GaAs quantum dot structures grown by molecular beam epitaxy

We report an optical spectroscopic study of GaSb/GaAs quantum dots (QDs) formed by the Stranski–Krastanow growth mode using molecular beam epitaxy. We identify the QD luminescence by photoluminescence obtained at different excitation energies and densities. We show that, for these structures, not only the spectral position of peaks, but also their relative intensities are critically dependent upon the density of photogenerated carriers. Photoluminescence excitation (PLE) measurements confirm our assignment of the QD related peaks and a feature ∼25–27 meV higher in energy than the PLE detection energy is discussed in terms of phonon relaxation.