Effects of temperature and HCl:NH3 flow ratio on the growth of GaN nanorods

We studied the formation of GaN nanorods on AlN-covered Si(111) by the hydride vapor phase epitaxy method. The most well-formed GaN nanorods were obtained at an HCl:NH3 gas flow ratio of 1:40 and a growth temperature of 650°C. A high density of straight nanorods with diameters of about 350nm formed uniformly over the entire substrate. The synthesis and structural properties of the nanorods were investigated by X-ray diffraction (XRD), scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDS). The obtained XRD patterns indicate that the GaN nanorods are preferentially oriented, with c-axes perpendicular to the substrate. EDS measurements of the nanorods indicate that they are composed of Ga and N with a ratio of 1.00:0.99.