418 cm − 1 Raman scattering from gallium nitride nanowires: Is it a vibration mode of N-rich Ga–N bond configuration?

A Raman-active vibration mode at 418cm−1 is observed in wurtzite gallium nitride (GaN) nanowires synthesized by different growth methods. In particular, Raman scattering measurements of a number of GaN nanowires systematically prepared by nitriding β-Ga2O3 nanowires at different temperatures show an interesting evolution of the mode, revealing that it is most likely the vibration mode of N-rich octahedral Ga–N6 bonds. This idea is further supported by the high-resolution transmission electron microscopic observation.