Controlled formation of GeSi nanostructures on periodic Si (001) sub-micro pillars

Self-assembled GeSi nanostructures on periodic Si (001) sub-micro pillars (SMPs) are systematically studied. Different GeSi nanostructures, including circularly arranged quantum dots, quantum rings and quantum dot molecules can be readily obtained at the edge of the pillars by controlling the growth temperatures and the diameter of the pillar. These phenomena are explained by taking into account the surface chemical potential around the top terrace of SMPs, which is considerably affected by the formation of {113} facets. Our results demonstrate a feasible route to obtain novel periodic Si pillars embedded with the desired GeSi nanostructures, which have promising applications in optoelectronic devices.