Mechanisms of 1D Crystal Growth in Reactive Vapor Transport:  Indium Nitride Nanowires

• Published in: Nano letters 2005-08, Vol.5 (8), p.1625-1631
• Main Authors: Vaddiraju, Sreeram, Mohite, Aditya, Chin, Alan, Meyyappan, M, Sumanasekera, Gamini, Alphenaar, Bruce W, Sunkara, Mahendra K
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Crystallization - methods; Electric Wiring; Electronics; Exact sciences and technology; Gases - analysis; Gases - chemistry; Indium - analysis; Indium - chemistry; Materials Testing; Microelectronic fabrication (materials and surfaces technology); Molecular Conformation; Motion; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Nanotubes - analysis; Nanotubes - chemistry; Nanotubes - ultrastructure; Nitrogen - analysis; Nitrogen - chemistry; Phase Transition; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Structure of solids and liquids; crystallography; Volatilization
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl0505804

Indium nitride (InN) nanowire synthesis using indium (In) vapor transport in a dissociated ammonia environment (reactive vapor transport) is studied in detail to understand the nucleation and growth mechanisms involved with the so-called “self-catalysis” schemes. The results show that the nucleation of InN crystal occurs first on the substrate. Later, In droplets are formed on top of the InN crystals because of selective wetting of In onto InN crystals. Further growth via liquid-phase epitaxy through In droplets leads the growth in one dimension (1D), resulting in the formation of InN nanowires. The details about the nucleation and growth aspects within these self-catalysis schemes are rationalized further by demonstrating the growth of heteroepitaxially oriented nanowire arrays on single-crystal substrates and “tree-like” morphologies on a variety of substrates. However, the direct nitridation of In droplets using dissociated ammonia results in the spontaneous nucleation and basal growth of nanowires directly from the In melt surface, which is quite different from the above-mentioned nucleation mechanism with the reactive vapor transport case. The InN nanowires exhibit a band gap of 0.8 eV, whereas the mixed phase of InN and In2O3 nanowires exhibit a peak at ∼1.9 eV in addition to that at 0.8 eV.