Formation of In0.5Ga0.5As ring-and-hole structure by droplet molecular beam epitaxy

Fabrication of InGaAs ring-and-hole nanostructures was successfully demonstrated by the droplet epitaxy technique using molecular beam epitaxy (MBE). The evolution of surface morphology during growth was monitored in situ by reflection high-energy electron diffraction (RHEED). Droplet-forming conditions were changed by varying substrate temperatures during In0.5Ga0.5 deposition (so-called deposition temperature). Dependence of the ring structural properties on the deposition temperature was investigated. Distributions of InGaAs ring outer diameter, outer height, and inner depth at different deposition temperatures were also examined. It was found that the higher the deposition temperatures, the larger the outer diameter and the higher the outer height of most of the InGaAs rings. However, they had slightly lower densities. Photoluminescence results confirmed the high quality of the nanocrystal.