Rational Growth of Branched and Hyperbranched Nanowire Structures

Branched and hyperbranched nanowire structures were synthesized via a multistep nanocluster-catalyzed vapor−liquid−solid approach. Scanning electron microscopy studies of silicon nanowire structures prepared in this way confirmed the formation of branched nanostructures and showed that the branch density could be controlled by the nanocluster catalyst concentration. This same approach was also used to grow branched gallium nitride nanowires. High-resolution transmission electron microscopy studies of the branched silicon nanowire structures revealed that the branches grew epitaxially as single-crystal nanowires from the silicon nanowire backbone. In addition, hyperbranched silicon nanowire structures were prepared in a controlled manner by repeating the catalyst deposition and nanowire growth steps. The ability to prepare rationally branched and hyperbranched nanowires should open up new opportunities for both fundamental research and applications, including three-dimensional nanoelectronics.