Outer zone morphology in GaAs ring/disk nanostructures by droplet epitaxy

We present the molecular beam epitaxy (MBE) fabrication of GaAs ring/disk nanostructures. In this system, a central quantum ring is surrounded by a flat outer disk-like region, which is developed following a layer-by-layer growth mode. Westudied the influence of the growth temperature on the morphology of these nanostructures and found out a pronounced dependence only for the outer region diameter, which is interpreted in terms of larger Ga atoms surface diffusion length at higher temperatures. Our experimental data provide a fundamental parameter to control the final shape of GaAs coupled ring/disk nanostructures.