Effect of an in-situ thermal annealing on the structural properties of self-assembled GaSb/GaAs quantum dots

[Display omitted] •GaSb QDs are more elongated and Sb is less concentrated after the thermal annealing.•The density of misfit dislocations in GaSb QDs is reduced after the annealing.•Threading dislocations in GaSb/GaAs QDs are Sb-rich after the thermal annealing.•The gliding of a threading dislocation favors Sb diffusion in GaSb/GaAs QDs. In this work, the effect of the application of a thermal annealing on the structural properties of GaSb/GaAs quantum dots (QDs)11Quantum dots. is analyzed by aberration corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM)22High-angle annular dark-field scanning transmission electron microscopy. and electron energy loss spectroscopy (EELS)33Electron energy loss spectroscopy. Our results show that the GaSb/GaAs QDs are more elongated after the annealing, and that the interfaces are less abrupt due to the Sb diffusion. We have also found a strong reduction in the misfit dislocation density with the annealing. The analysis by EELS of a threading dislocation has shown that the dislocation core is rich in Sb. In addition, the region of the GaAs substrate delimited by the threading dislocation is shown to be Sb-rich as well. An enhanced diffusion of Sb due to a mechanism assisted by the dislocation movement is discussed.