Title: Self assembled ZnO hollow spheres and hexagonal stacking disks by metal-organic chemical-vapour deposition

Authors: S.T. Tan, X.W. Sun, X.H. Zhang, S.J. Chua, S.Y. Chow, A.M. Yong, G.Q. Lo, D.L. Kwong

Addresses: School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore; 11 Science Park Road, Science Park II, Singapore 117685, Singapore. ' School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore; 11 Science Park Road, Science Park II, Singapore 117685, Singapore. ' Institute of Materials Research and Engineering, 3 Research Link, 117602, Singapore. ' Institute of Materials Research and Engineering, 3 Research Link, 117602, Singapore. ' Institute of Materials Research and Engineering, 3 Research Link, 117602, Singapore. ' Institute of Materials Research and Engineering, 3 Research Link, 117602, Singapore. ' Institute of Microelectronics, 11 Science Park Road, Science Park II, 117685, Singapore. ' Institute of Microelectronics, 11 Science Park Road, Science Park II, 117685, Singapore

Abstract: Self-assembled ZnO hollow spheres and hexagonal stacking disks were synthesised by metal-organic chemical-vapour deposition. The growth process was investigated as a function of time and the sphere and disk structures were obtained in a narrow window of a near-zero oxygen partial pressure. The largest hollow sphere has a diameter up to 20 µm with a shell thickness of around 200 nm formed by nanocrystals or nanodisks. The hexagonal stacking disks were found to be covered with a few nanometres thick of metallic Zn observed by high-resolution transmission electron microscopy. The accumulation and dissociation of diethylzinc through beta hydride elimination process in the near-zero oxygen partial pressure was thought to be the reason for the formation of the hollow spheres and stacking disks.

Keywords: ZnO; hollow spheres; MOCVD; wide-bandgap semiconductors; nanostructures; self assembly; nanotechnology; hexagonal stacking disks; metal-organic CVD; chemical vapour deposition; diethylzinc; beta hydride elimination; zinc oxide.

DOI: 10.1504/IJNT.2007.015464

International Journal of Nanotechnology, 2007 Vol.4 No.6, pp.691 - 701

Published online: 18 Oct 2007 *

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