Collector Phase Transitions during Vapor-Solid-Solid Nucleation of GaN Nanowires

We investigate the nucleation of Ni-induced GaN nanowires by in situ and ex situ experiments. Three nucleation stages are evidenced. in the first two stages, different crystal structures of the Ni collectors are identified. Real-time monitoring of the Ga desorption allows the amount of Ga incorporated in the collectors to be quantified. A transition of their crystal structure prior to nanowire growth is found to be in agreement with the thermodynamically stable phase sequence of the relevant phase diagrams.