Optical spectroscopy of GaSb/GaAs self-assembled quantum dots grown by MOCVD

We report results for optical spectroscopy of GaSb self-assembled quantum dots (QDs) grown by metalorganic chemical vapour deposition (MOCVD) on GaAs substrates. We examined the QD emission by room temperature cathodoluminescence (CL) and low temperature photoluminescence (PL). In samples grown for 3, 5, and 7 seconds cathodoluminescence spectra show evidence of quantum confinement with peaks shifted to higher energies of 0.95, 1, and 1.05 eV respectively, reflecting the decreasing average size of the dots grown at longer times. The cathodoluminescence emission intensity of the quantum dots depends on the electron excitation voltage of between 15 kV and 35 kV. It also varies with beam current density and this variation is related to the generation of secondary electrons in the GaAs barrier. The cathodoluminescence signal is also confirmed by photoluminescence studies.