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Open Access Nano Express

Highly Uniform Epitaxial ZnO Nanorod Arrays for Nanopiezotronics

J Volk12*, T Nagata2, R Erdélyi1, I Bársony1, AL Tóth1, IE Lukács1, Zs Czigány1, H Tomimoto2, Y Shingaya2 and T Chikyow2

Author Affiliations

1 Research Institute for Technical Physics and Materials Science, Konkoly Thege Miklós út 29-33, 1121, Budapest, Hungary

2 National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan

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Nanoscale Research Letters 2009, 4:699-704  doi:10.1007/s11671-009-9302-1

Published: 7 April 2009

Abstract

Highly uniform and c-axis-aligned ZnO nanorod arrays were fabricated in predefined patterns by a low temperature homoepitaxial aqueous chemical method. The nucleation seed patterns were realized in polymer and in metal thin films, resulting in, all-ZnO and bottom-contacted structures, respectively. Both of them show excellent geometrical uniformity: the cross-sectional uniformity according to the scanning electron micrographs across the array is lower than 2%. The diameter of the hexagonal prism-shaped nanorods can be set in the range of 90–170 nm while their typical length achievable is 0.5–2.3 μm. The effect of the surface polarity was also examined, however, no significant difference was found between the arrays grown on Zn-terminated and on O-terminated face of the ZnO single crystal. The transmission electron microscopy observation revealed the single crystalline nature of the nanorods. The current–voltage characteristics taken on an individual nanorod contacted by a Au-coated atomic force microscope tip reflected Schottky-type behavior. The geometrical uniformity, the designable pattern, and the electrical properties make the presented nanorod arrays ideal candidates to be used in ZnO-based DC nanogenerator and in next-generation integrated piezoelectric nano-electromechanical systems (NEMS).

Keywords:
Aqueous chemical growth; Vertical nanowire; Nanogenerator; NEMS; Piezoelectricity; Rod-type photonic crystal