Self-assembled GaAs/AlGaAs coupled quantum ring-disk structures by droplet epitaxy.

The fabrication, by droplet epitaxy, of a class of quantum nanostructures characterized by a regular, nanometres high, flat disks with a diameter of hundreds of nanometres and a hole at the centre encircled by a ring a few nanometres high, is presented here. A detailed analysis of the growth kinetics performed via in situ and ex situ probes allows us to propose a working model for the formation of these structures.