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 L 1₂ 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.