Synthesis and optical properties of sword-like GaN nanorods clusters

Purpose of this work is to synthesize highly pure gallium nitride (GaN) nanomaterials without using any foreign materials as a catalyst to avoid unintentional metal contamination. Therefore, a simple method for synthesizing sword-like GaN nanorods clusters has been proposed through ammoniating a new type of single molecular complex precursor [ammoniumhexafluro gallate, (NH4)3GaF6], under a flow of ammonia gas. We investigated that the growth of sword-like GaN nanorods clusters was mainly depending on the decomposition rate of ammonia and the availability of sufficient amount of atomic nitrogen (N) species. Sword-like GaN nanorods clusters consist of outwardly orientated nanorods grown from the central part of source material to all possible direction, but not parallel to the substrate. Average diameters of an individual nanorod were found to be around 700, 350, and 100 nm from the bottom, middle and near top portion, respectively. The characteristic peaks in X-ray diffraction and Raman spectra were substantiated that the nanorods are pure hexagonal GaN with single crystalline wurtzite structure. Morphology and high crystal structure of GaN nanorods clusters were confirmed by the scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM).