We present the molecular beam epitaxy fabrication and optical
properties of complex GaAs nanostructures by droplet epitaxy:
concentric triple quantum rings. A significant difference was
found between the volumes of the original droplets and the final
GaAs structures. By means of atomic force microscopy and
photoluminescence spectroscopy, we found that a thin GaAs
quantum well-like layer is developed all over the substrate
during the growth interruption times, caused by the migration of
Ga in a low As background. Keywords:Molecular beam epitaxy;
Droplet epitaxy; GaAs nanostructures; Photoluminescence The
fabrication of semiconductor quantum nanostructures based on
self-assembly has deeply attracted the research community
because of the interest in fundamental physics and the potential
applications of these systems as building blocks for novel
devices and quantum information technologies [1-3]. In
particular, quantum rings, a special class of semiconductor
nanostructures, have been investigated since they manif