Various one-dimensional GaN nanostructures formed by non-catalytic routes

GaN crystals were nucleated and grown into various one-dimensional forms by the supersayuration of a source gas via non-catalytic routes. Chemical vapor deposition (CVD) was employed for the GaN growth using Ga metal and ammonia gas as sources. The formation of one-dimensional GaN naostructures including nano-columns, nano-cakes, nano-flowers, and nano-bundles was identified using scanning electron microscopy (SEM). X-ray diffraction (XRD) was performed to analyze crystallinity of each nanostructure. The growth mechanism of thick nano-columns was proposed as the epitaxial growth of GaN (002) hexagonal columns with {100} facets from the GaN thick films. The growth of nano-cakes was suggested as the (002) hexagonal plate formation with {100} facets at the first stage followed by the secondary (002) crystal growth from each plate. The growth mechanism of nano-flowers would be the formation of GaN seed particles first and the subsequent nucleation and growth of GaN (101) nanowires with several directions from the seeds. The growth of nano-bundles is the most interesting structure and the formation mechanism was proposed as the first formation of a GaN (002) nanowire and then subsequent nucleation and growth of GaN (002) and (10-1) nanocrystals at the surface of the primary GaN (002) nanowire.