Control over the Number Density and Diameter of GaAsNanowires on Si(111) Mediated by Droplet Epitaxy.

Wepresent a novel approach for the growth of GaAs nanowires (NWs) withcontrollable number density and diameter, which consists of the combinationbetween droplet epitaxy (DE) and self-assisted NW growth. In our method,GaAs islands are initially formed on Si(111) by DE and, subsequently,GaAs NWs are selectively grown on their top facet, which acts as anucleation site. By DE, we can successfully tailor the number densityand diameter of the template of initial GaAs islands and the samedegree of control is transferred to the final GaAs NWs. We show how,by a suitable choice of V/III flux ratio, a single NW can be accommodatedon top of each GaAs base island. By transmission electron microscopy,as well as cathodo- and photoluminescence spectroscopy, we confirmedthe high structural and optical quality of GaAs NWs grown by our method.We believe that this combined approach can be more generally appliedto the fabrication of different homo- or heteroepitaxial NWs, nucleatedon the top of predefined islands obtained by DE. [ABSTRACT FROM AUTHOR]