Surface-diffusion induced growth of ZnO nanowires

• Published in: Journal of crystal growth 2009-05, Vol.311 (11), p.3216-3219
• Main Authors: Kim, D.S., Gösele, U., Zacharias, M.
• Format: Article
• Language: English
• Subjects: A1. Nanowires; A3. Vapor phase epitaxy; B1. Zinc oxide; B2. Semiconducting II–VI materials; Cross-disciplinary physics: materials science; rheology; Crystal growth; Epitaxial growth; Exact sciences and technology; Free energy; Gallium nitrides; Inverse; Materials science; Methods of crystal growth; physics of crystal growth; Methods of nanofabrication; Nanoscale materials and structures: fabrication and characterization; Nanowires; Other topics in nanoscale materials and structures; Physics; Polarity; Quantum wires; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Zinc oxide
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2009.03.026

The growth rate of ZnO nanowires grown epitaxially on GaN/sapphire substrates is studied. An inverse proportional relation between diameter and length of the nanowires is observed, i.e., nanowires with smaller diameters grow faster than larger ones. This unexpected result is attributed to surface diffusion of ZnO admolecules along the sidewalls of the nanowires. In addition, the unique c-axis growth of ZnO nanowires, which does not require a catalytic particle at the tip of the growing nanowires is discussed by taking into account polarity, surface free energy, and ionicity. Activation energies of the nanowire growth are determined as well.