Evolution of InAs branches in InAs/GaAs nanowire heterostructures

Branched nanowire heterostructures of InAs/GaAs were observed during Au-assisted growth of InAs on GaAs nanowires. The evolution of these branches has been determined through detailed electron microscopy characterization with the following sequence: (1) in the initial stage of InAs growth, the Au droplet is observed to slide down the side of the GaAs nanowire, (2) the downward movement of Au nanoparticle later terminates when the nanoparticle encounters InAs growing radially on the GaAs nanowire sidewalls, and (3) with further supply of In and As vapor reactants, the Au nanoparticles assist the formation of InAs branches with a well-defined orientation relationship with GaAs/InAs core/shell stems. We anticipate that these observations advance the understanding of the kink formation in axial nanowire heterostructures. (C) 2007 American Institute of Physics.