Effect of Ga deposition rates on GaSb nanostructures grown by droplet epitaxy

We investigate the effect of Ga deposition rates on GaSb nanostructures grown by droplet epitaxy on GaAs (001) substrates. Ga deposition rate was varied to form the different size and density of Ga droplets. After the droplets were exposed to Sb flux, not only the GaSb ring structure but also the complex nanostructure like the GaSb ring structure surrounded by ring-shaped dot molecules were obtained. A simple descriptive model is proposed to describe formation mechanisms of these nanostructures. It is found that Ga droplet size, distance between Ga droplets and diffusion area of Ga atoms during crystallization with Sb flux are all the crucial factors which determine the shape of GaSb nanostructures. Due to a lattice mismatch between GaSb and GaAs, strain occurred during a crystallization process should also be taken into account. Photoluminescence was carried out to verify our model.