Synthesis of GaN nanowires and nanorods via self-growth mode control

The synthesis of hexagonal wurzite one-dimensional (1D) GaN nanostructures on c-Al2O3 substrates was investigated using a thermal chemical vapor deposition (CVD) process. The diameter of the GaN nanostructures was controlled by varying the growth time using a mixture of GaN powder and Ga metal with the ammonia gas reaction. The morphologies of the GaN nanowires and nanorods were confirmed by field emission scanning electron microscopy. The micro-Raman spectroscopy and X-ray scattering measurements indicated that the GaN nanostructures had a hexagonal wurzite structure without any oxide phases. We investigated the difference in the structural properties between the GaN nanowires and nanorods. Deep-level emission bands were not observed in cathodoluminescence measurements from either the GaN nanowires or nanorods, indicating the incorporation of low-level impurities into our 1D GaN nanostructures.