MOCVD of gallium nitride nanostructures using (N₃)₂Ga{(CH₂)₃NR₂}, R = Me, Et, as a single molecule precursor: Morphology control and materials characterization

Gallium nitride nanostructures such as nanopillars, nanorods and nanowires were grown by metal organic chemical vapor deposition (MOCVD) on a c-plane sapphire substrate using the single molecule precursors (SMPs) bisazido(dimethylaminopropyl)gallium (BAZIGA, 1) and its ethyl derivative bisazido(diethylaminopropyl)gallium (E-BAZIGA, 2) in horizontal and vertical stagnation flow cold-wall reactors. It has been found that, at a given growth temperature, H₂ and the total pressure have a profound influence on the morphology of the GaN nanostructure, which changes front self-organized nanopillars to randomly oriented nanowires through dense, ordered nanorods. The GaN nanopillars grown by SMPs 1 and 2 in the presence of N₂ were most likely to follow a vapor-liquid-solid (VLS) autocatalytic growth process and exhibit a surface distribution density of 3.8 × 10¹⁰-4.5 × 10¹² cm^-2, whereas GaN nanorods and nanowires were produced in the presence of various amounts of H₂. The surface distribution density in the case of the nanorods was dependent on the H₂ flow. X-Ray diffraction and selected area electron diffraction revealed that the nanostructures were a single crystalline and hexagonal modification of GaN. The nanostructures were easily detached front the substrate and dispersed in organic solvents and showed strong photoluminescence in the near UV region (2.7-3.0 eV).