Exceptional Crystal-Defined Bunched and Hyperbunched GaN Nanorods Grown by Catalyst-Free HVPE

• Published in: Crystal growth & design Vol. 12; no. 5; pp. 2251 - 2256
• Main Authors: Lekhal, K, André, Y, Trassoudaine, A, Gil, E, Avit, G, Cellier, J, Castelluci, D
• Format: Journal Article
• Language: English
• Published: Washington,DC American Chemical Society 02.05.2012
• Subjects: Chemistry; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; General and physical chemistry; General, apparatus; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Methods of nanofabrication; Nanoscale materials and structures: fabrication and characterization; Physics; Quantum wires; Surface physical chemistry; Vapor phase epitaxy; growth from vapor phase; Scanning electron microscopy; Nucleation; Catalysts; Vapor condensation; Field emission; VPE; Hydrides; XRD; Gallium nitride; Crystal symmetry; III-V compound; Ammonia; Hexagonal lattices; Temperature effects; Growth mechanism; Crystal morphology; Nanorod; Nanostructured materials; Nanomaterial synthesis; III-V semiconductors
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg201484q

GaN nanorods (NRs) with exceptional crystal-defined morphologies were grown by near-equilibrium hydride vapor phase epitaxy (HVPE) on c-plane sapphire (0001) and silicon (111) substrates. Hexagonal faceted individual, bunched, and hyperbunched GaN NRs were synthesized by using a catalyst-free process. GaN NRs with a diameter in the range of 125–700 nm and a length in the range of 0.9–3 μm were grown in a record short process time of 30 min. The influence of growth temperature and ammonia gas flow rate was investigated to establish the nucleation and the growth mechanisms of the GaN NRs. Shape and crystallographic facets of the NRs are discussed and a condensation growth mechanism is proposed for the formation of bunched GaN NRs. Emphasis is placed on the crystal symmetry of the nuclei in the first stage of growth. The morphology and the structural properties were analyzed by field emission scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD).