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

Abstract

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 from 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 from the substrate and dispersed in organic solvents and showed strong photoluminescence in the near UV region (2.7–3.0 eV).