The nature of catalyst particles and growth mechanisms of GaN nanowires grown by Ni-assisted metal-organic chemical vapor deposition

The structure and chemistry of the catalyst particles that terminate GaN nanowires grown by Ni-assisted metal-organic chemical vapor deposition were investigated using a combination of electron diffraction, high-resolution transmission electron microscopy, and x-ray energy dispersive spectrometry. The crystal symmetry, lattice parameter, and chemical composition obtained reveal that the catalyst particles are Ni3Ga with an ordered L1(2) structure. The results suggest that the catalyst is a solid particle during growth and therefore favor a vapor-solid-solid mechanism for the growth of GaN nanowires under these conditions.